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Copyright of Cardiologia Croatica is the property of Croatian Cardiac Society and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: Endomyocardial biopsy (EMB) is the gold standard in heart transplantation (HTx) followup, with samples commonly fixed with formalin, and then embedded in paraffin for histology analysis. Recently, EMB samples have been scanned with synchrotron X-ray phase-contrast imaging (X-PCI) to assess graft rejection.¹ We aim to compare imaging time efficiency and image quality between formalin-fixed and paraffin-embedded samples to determine the optimal scanning methodology. Methods: Three adult patients undergoing EMB after HTx were included. EMB samples were initially stored in formalin and imaged by X-PCI at the Paul Scherrer Institute TOMCAT beamline (Villigen, Switzerland). On site samples were scanned in glass tubes in deionised, degassed water, and then embedded in paraffin, positioned on a holder, and scanned again using a multi-scale beamline set-up. Imaging time efficiency was measured by on-site sample preparation and scan time, and image quality was assessed with signal-to-noise ratio (SNR) and pixel resolution. Post-processing comparison included fibrosis quantification (using Ilastik for segmentation and Fiji for calculating the average percentage of collagen in 3 selected areas) and graft-rejection grading (assessed by two blinded observers based on the ISHLT 2004. criteria)². Results: Scanning F1-F3 and P1-P3 samples produced the same imaging resolution, while F1-F3 samples exhibited higher SNR values (clearer sample visibility) (Table 1). On site preparation and scan time were shorter with P1-P3 samples. Fibrosis quantification produced similar results in all samples, with Embedding EMB samples in paraffin is more time efficient in terms of on-site sample preparation and imaging. Results showed similar fibrosis quantification regardless of preparation methods, whereas rejection grading did not differ in clinically meaningful way. In conclusion, in initial testing using small sample number, no significant difference was found between the preparation methods. [ABSTRACT FROM AUTHOR]

Introduction: Direct oral anticoagulants (DOACs) are recommended in preference to vitamin K antagonists (VKA) in patients with atrial fibrillation (Afib)1 . There is no direct comparison between DOACs and substantial share of patients are still treated with VKAs due to certain comorbidities or financial reasons. Pulmonary vein isolation (PVI) is an established procedure to treat paroxysmal and persis tent Afib but it increases thromboembolic risk². The aim of this study was to compare periinterventional platelet reactivity (PR) in Afib patients undergoing PVI on different chronic oral anticoagulation. Patients and Methods: PR was analyzed with Multiplate function analyzer in 136 patients undergoing PVI procedures in our institution. Blood samples were drawn before the procedure and on the following morning. ASPItest, ADPtest and TRAPtest were used as assays for the quantitative in vitro determination of PR triggered by arachidonic acid, adenosine diphosphate and thrombin receptor activating peptide-6, respectively. Fourty three patients (31.6%) were taking VKA, while 38 (27.9%), 29 (21.3%) and 26 (19.1%) patients were treated with dabigatran, rivaroxaban and apixaban, respectively. Edoxaban was not available during the investigation. Results: There was no significant difference in demographics between the groups. Patients on VKA had lower mean platelet volume (MPV) compared to patients on DOACs (9.9 vs 10.7-10.8 fL; p=0.020). Patients on xabans (rivaroxaban and apixaban) had lower baseline PR compared to VKA and dabigatran (Table 1). One day after PVI, there was no significant change from PR baseline in all four groups (Figure 1). Conclusion: Our results show that there is no significant effect of PVI on PR one day after the procedure regardless of chronic oral anticoagulation that was used. Lower basal PR was noted in patients on xabans compared to direct thrombin inhibitor and VKA. This antiplatelet mechanism is not fully understood but might be associated with multiple direct and indirect pathways which could contribute to potential differences in events between patients on certain DOACs. This warrants further investigation in seeking optimal DOAC choice for each patient. [ABSTRACT FROM AUTHOR]

Background: Pregnancy in heart transplant (HT) recipients with episodes of rejection or positive donor specific antibodies (DSA) is discouraged by all recommendations due to higher risk of complications. Although there is paucity of data for DSA trend during pregnancy in HT recipients, there is evidence of improvement of symptoms during pregnancy in some autoimmune diseases1-3. Case report: 23-year-old female who underwent HT due to post-myocarditis cardiomyopathy in June 2014, reported unplanned pregnancy in June 2022. She had a history of acute cellular (3R/3B) and humoral rejection (DSA major histocompatibility complex (HLA) class I, specificity A11, A30, B13, B35 and HLA class II, specificity DR3, DR15, DR51, DR52, DQ2, mean fluorescent intensity (MFI) 1000-13 300) in August 2017 which required mechanical circulatory support due to severe heart failure with multiorgan damage. She underwent pulse corticosteroid treatment, and 12 cycles of plasmapheresis with administration of rituximab, intravenous immunoglobulins, and thymoglobulin. After that she had persistent positive DSA, predominantly DQ2 (MFI up to 12200), and because of that was on quadruple immunosuppression (tacrolimus, mycophenolate (MMF), everolimus, prednisone) from October 2019 to July 2020 when MMF was discontinued due to gastrointestinal side effects. She had one more cellular rejection episode (2R/3A) in March 2022 which was treated with pulse corticosteroids. During pregnancy she was on tacrolimus, everolimus, and prednisone combination with closely monitoring of immunosuppressants concentrations. Echocardiography controls showed normal left ventricle function and mildly reduced right ventricle function, NT-proBNP was slightly elevated (493-823 ng/L) and DSA were in a downward trend which is shown in Figure 1. At 32+3 weeks of pregnancy, she was hospitalized due to early labor. The following day male baby was delivered by Caesarean section due to pathological cardiotocography (Apgar score 8/9). After delivery DSA remained weakly positive. Conclusion: Although pregnancy in HT recipients with history of rejection and positive DSA is discouraged, positive outcome is possible with close monitoring of multidisciplinary team. Furthermore, we described a rare case of downward trend of positive DSA during pregnancy. [ABSTRACT FROM AUTHOR]

Introduction: Pulmonary vein isolation (PVI) is an established procedure to treat atrial fibrillation (Afib) but it increases periinterventional thromboembolic burden¹ . Literature provides ambiguous results about ablation effects on different hemostatic markers. The aim of this study was to assess the difference between two used PVI methods (cryoablation and radiofrequency ablation (RFA)) in postinterventional platelet reactivity (PR). Patients and Methods: We analyzed PR in 168 consecutive patients undergoing PVI due to Afib in our institution using Multiplate function analyzer. Blood samples for PR measurements were drawn prior to the procedure and the on the following morning. In total, 123 and 45 patients underwent cryoablation and RFA, respectively. There was no difference in demographics and baseline platelet parameters between the groups (Table 1). ASPItest, ADPtest and TRAPtest were used as assays for the quantitative in vitro determination of PR triggered by arachidonic acid, adenosine diphosphate and thrombin receptor activating peptide-6, respectively. [ABSTRACT FROM AUTHOR]

Background: Mitral regurgitation (MR) is a common valvular heart disease1 . Without treatment prognosis is poor, especially if left ventricular (LV) function is reduced2. In high-risk patients who are not eligible candidates for surgery or transcatheter edge-to-edge repair (TEER), transcatheter mitral valve replacement (TMVR) is a viable option2,3. All-cause mortality is highest 3-months after valve implantation, while improvement in symptoms and reduction of MR severity are sustained after 2-years of follow-up2. Case series: From April to July 2023, four high-risk patients underwent TMVR with TendyneTM valve (Abbott Vascular, CA, USA) implantation in UHC Zagreb. Case 1 is a 75-year-old female with degenerative MR and preserved LV function – due to fragility and comorbidities the patient was not a candidate for mitral valve (MV) surgery, while due to calcification and MV leaflet morphology TEER was denied. After successful TMVR, mean pressure gradient was 4-5mmHg, no residual MR. Case 2 is a 72-year-old-male with ischemic cardiomyopathy (CMP) who underwent CABG 20 years ago. Due to heart failure, atrial fibrillation with bradycardia and LBBB, CRT was implanted. Because of severe MR due to prolapse P1/P2 and chordal rupture, the patient was a candidate for TMVR – postprocedural mean PG was 5-6mmHg, no residual MR. Case 3 is a 76-year-old female with toxic CMP after chemotherapy for breast cancer and functional MR. Due to deep indentations on the posterior leaflet, TEER was denied, so TMVR was performed – post implantation mean PG was 3mmHg, no residual MR. Case 4 is a 65-year-old male to whom surgical AVR was performed in 2017 due to endocarditis. In 8/2022 due to prosthesis degeneration and HF, he underwent valve-in-valve TAVI. Re-do surgery at that time was denied due to comorbidities (end-stage renal disease- on hemodialysis, COPD, toxic liver lesion), even though severe degenerative MR was also known. Clinical improvement after TAVI was significant, but he was hospitalized due to HF, and MR did not improve, so he was referred for TMVR. After TMVR, mean PG was 6-7mmHg with trace of paravalvular MR. [ABSTRACT FROM AUTHOR]

Introduction: Immune mediated vascular damage is a major risk for cardiac allograft vasculopathy (CAV). Anti-thymocyte globulin (rATG) provides intense immunosuppression early after HTx. The role of rATG on CAV prevention still remains controversial.1,2 While lymphopenia reflects the therapeutic effect of rATG, a decrease in platelet count is deemed as an adverse effect. We hypothesize that lower lymphocyte and platelet counts following rATG induction may be associated with less risk for the development of CAV. Patients and Methods: We performed a retrospective single-centre study in patients transplanted between 2010 and 2017. All pts received rATG induction therapy for 5 days. Absolute lymphocyte count (ALC) and platelet count were assessed on days 0, 7, 14, and 21 following HTx. The primary outcome was the diagnosis of CAV grade ≥1, during 3 years of follow-up. Results: A total of 133 pts were transplanted in this period. During first three years after HTx 18.8% of pts developed CAV≥1. Those pts had sig nificantly older donors (47 (IQR 40-49) vs 37 (IQR 28-49), p=0.02), higher median platelet count on day 7 (140 x 109 /L (IQR 103-156 X 109 /L) vs 105 x 109 /L (IQR 68-147 x 109 /L), p=0.04), higher median lymphocyte count on day 14 (335 x 109 /L (IQR 184-314 x 109 /L vs 215 x 109 /L (IQR 105-401 x 109 /L), p=0.02), higher median leukocyte count on day 21 (810 x 10³ /µL (IQR 600-960 x 10³ /µL) vs 660 x 10³ /µL (IQR 500-794 x 10³ /µL), p=0.03), and higher median platelet count on day 21 post HTx (237 x 109 /L (IQR 195-278 x 109 /L) vs 193 x 109 /L (IQR 148-226 x 109 /L), p=0.03) than the pts without CAV. Univariate binary logistic regression showed that CAV was associated with older donor age, lymphocyte count ≥200 x 109 /L on day 7, higher platelet count on day 7 and 21, and higher leukocyte count on day 21. In multivariable binary logistic regression, the adjusted risk of CAV was significantly higher for pts with older donors (p=0.027), and higher platelet count on day 21 (p=0.04). Conclusion: Lower platelet count after induction with rATG was associated with lower incidence of CAV. Association with lower lymphocyte count in univariate logistic regression did not reach significance in multivariable analysis. The controversial reports on clinical benefit from rATG induction on CAV prevention could be explained by variable platelet response of the recipients to the therapy. [ABSTRACT FROM AUTHOR]

Background: Ventricular tachycardia (VT) commonly occurs in patients with structural heart disease, either of ischemic or non-ischemic nature. Treatment options include various antiarrhythmic drugs (AADs) and implantable cardioverter-defibrillators (ICDs). When AADs fail, radiofrequency (RF) catheter ablation is a valuable treatment option for patients with recurrent VT.1 This single-center ten-year retrospective study aimed to assess acute and chronic success rates of RF catheter ablation and to identify predictors of VT recurrence and patient survival. Patients and Methods: We analyzed all consecutive patients with structural heart disease who underwent RF catheter ablation of VT in our institution from 2011 to 2021. Data were collected from existing hospital electronic medical records. Results: A total of 72 patients (89% male, mean age 62 years, 28% with non-ischemic cardiomyopathy, mean LVEF 35%) were included. Non-inducibility was achieved in 64.7% of cases. One year VT recurrence rate was 41.6%. Substrate ablation significantly reduced the frequency of ICD shocks (14% vs. 60%, p = 0.001). The overall one-year survival was 86%. In multivariate analysis, VT inducibility was an independent predictor of VT recurrence (p = 0.02; OR = 13.5; 95% CI = 1.46-124.7). Female gender was an independent negative risk factor for patient survival (p = 0.03; OR = 7.19; 95 % CI = 1.22-42.6). Conclusion: Our data show that RF catheter ablation of VT can be a feasible treatment option for patients with frequent AAD-refractory VTs with acceptable acute and chronic success rates, even in midvolume centers like ours. VT ablation can reduce the frequency of ICD shocks and improve patients’ quality of life. Institutional registry can help monitor and improve outcomes and provide valuable feedback. [ABSTRACT FROM AUTHOR]

The goal: The goal was to show results of a long-term follow-up following the cryoballoon pulmonary vein isolation in patients with atrial fibrillation (AF). Patients and Methods: A total of 126 patients were included in the study of which 77.0% had paroxysmal atrial fibrillation (PAF). Successful treatment outcome was defined as AF recurrence- free survival with stabile sinus rhythm during a 5-year period after the procedure. A treatment failure was defined as symptomatic AF recurrence with ECG verification (12 lead ECG or AF lasting >30s by Holter EKG). The patients on antiarrhythmic therapy and those that underwent a redo pulmonary vein isolation procedure were also included. Results: Following cryoballon pulmonary vein isolation in a 5-year period 52.4% of patients were in stable synus rhythm without AF recurrence. With redo pulmonary vein procedures a total of 61.9% of patients was without AF recurrence. Together with antiarrhythmic drugs 57.9% of patients was in sinus rhythm without AF recurrence in a 5-year period. With redo pulmonary vein isolation and antiarrhytmic drugs a total of 73.8% of patients were without AF recurrence. There was statistically significant difference regarding AF recurrence between patients that underwent redo pulmonary vein isolation and those that did not (p=0.006). In patients with PAF, 62.9% remained without AF recurrence and 79.4% who underwent redo procedure. In patients with persistent atrial fibrillation (PersAF), 41.4% was without AF recurrence and 55.1% that underwent a redo procedure. The difference between PAF and PersAF was statistically significant (p=0.009). Conclusion: Data from our centre show good long-term results of cryoballoon pulmonary vein isolation in patients with atrial fibrilation. The procedure is especially successful in patients with PAF.1 The use of redo procedures is justified as it increases long-term success rate. [ABSTRACT FROM AUTHOR]

Introduction: Virus associated hemophagocytic syndrome (VAHS) is severe complication of numerous viral infections that is associated with “cytokine storm” and the accumulation of activated T-lymphocytes and macrophages in various organs, frequently resulting in multiorgan failure and death1,2. We present a case report of VAHS caused by Influenza A infection. Case report: 50-years old, previously healthy male presented to Emergency Department with fever and respiratory failure. Initial arterial blood gases showed global respiratory failure with acidosis (pH < 6.8, pCO2 9.3 kPa, pO2 8.7 kPa, lactates 13.5 mmol/L, HCO3- unmeasurable). Computed tomography showed left sided pneumonia, and initial laboratory workup showed severe leukopenia, elevated C-reactive protein, and mild renal lesion (Table 1). Polymerase Chain Reaction (PCR) was positive for Influenza A, and Streptococcus Pyogenes was isolated from bronchoalveolar lavage. After initial workup patient arrested and cardiopulmonary reanimation (CPR) with intubation was performed. Post-CPR echocardiography showed severely reduced left ventricular systolic function (LVEF <15%) with suspected thrombus in left ventricle (Figure 1). Patient was hemodynamically unstable despite massive volume resuscitation, vasopressors, and inotropes so under ultrasound guidance veno-arterial extracorporeal membrane oxygenation (VA-ECMO) was placed. Hemodialysis with Oxyris filter was initiated. Because of severe pancytopenia bone marrow biopsy was performed which confirmed VAHS. Treatment included Pentaglobin and intravenous immunoglobulins supplementation, high doses of glucocorticoids and cyclosporin A. After 5 days ECMO configuration was changed to VAV ECMO because of suboptimal peripheral oxygenation. Bedside echocardiography was performed every day and gradual recovery of LVEF was verified and because of that, seven days after admission ECMO configuration was changed to VV ECMO. Total ECMO support time was 20 days. Because of prolonged mechanical ventilation percutaneous tracheotomy was performed. Treatment complications included multiple hospital acquired infections, cytomegalovirus reactivation, necrosis of all toes and two fingers, severe critical illness polyneuropathy, cachexia, acalculous cholecystitis. After 3 month of treatment patient is in process of weaning from mechanical ventilation. Conclusion: VAHS is one of rare and potentially lethal complications of Influenza A which can lead to multiorgan failure that can require mechanical circulatory support. Echocardiography plays crucial role in diagnostics and management of critical ill patients. [ABSTRACT FROM AUTHOR]

Introduction: The efficiency of drug-coated balloon (DCB) percutaneous coronary intervention (PCI) has been shown for in-stent restenosis (ISR) and native small-vessel disease, with available data showing similar outcomes in both chronic kidney disease (CKD) and non-CKD patients1. The aim is to compare the incidence of target lesion restenosis at follow-up (FUP) coronary angiography in patients with and without CKD receiving DCB PCI. Patients and Methods: The registry included patients undergoing a DCB PCI at the University Hospital Centre Zagreb from February 2011 to January 2023 (n=652). Patient demographics, comorbidities, pharmacotherapy, as well as data on the initial and FUP coronary angiography/PCI was collected. Chronic kidney disease was defined as estimated glomerular filtration rate < 45 ml/ min/1.73m2. A FUP angiography was performed in 49% of patients (n=317), with a median FUP of 6 (interquartile range 3 - 18) months, without difference between groups. Results: Data is shown in Table 1. The cohort was 75% male, mean age 65 ± 10 years. CKD was present in 9% (n=57) of patients and was associated with a higher incidence of arterial hypertension, diabetes mellitus, atrial fibrillation, as well as peripheral artery disease. The age difference was noted between groups, with CKD patients being older on average. At initial PCI, more CKD patients had multivessel coronary disease, with a higher rate of ISR as the indication for DCB, that was not statistically significant (CKD vs non-CKD: 46% vs 34%, p=0.075). After DCB, no difference was noted between groups in regards to the need for a bail-out PCI (9% VS 6%, P=0.375). FUP was performed in an equal percentage of patients in both groups (48% vs 51%, p=0.769), with no differences seen in the incidence of restenosis (17% vs. 18%, p=0.998), the need for target lesion PCI (17% vs. 13%, p=0.533), or the use of anti-anginal drugs. Conclusion: The findings of our single-centre analysis show that patients with CKD do not have a higher risk of target lesion restenosis after DCB PCI, when compared to the non-CKD group, which is in accordance with currently available evidence2. [ABSTRACT FROM AUTHOR]

Introduction: Acute coronary syndrome (ACS), including ST-segment elevation myocardial infarction (STEMI), non-ST-elevation myocardial infarction (NSTEMI) and unstable angina pectoris (UA), has been less researched in the subpopulation of young patients. Sex differences in discharge therapy after ACS have been described in older patients as favouring the male sex, and we decided to test this hypothesis in young patients. The term “young” (with regard to ACS) is not uniquely defined, but according to multiple sources, the proposed cut-off age is 45 years. Patients and Methods: A total of 361 young patients (with an age cut-off of 45 years for men and 55 years for women) with ACS and percutaneous coronary intervention (PCI) performed at the University Hospital Centre Zagreb (UHCZG) between Jan 1st 2012 and Jan 1st 2020 were enrolled. The patients were divided into the UHCZG group (241 patients discharged home after ACS) and the PCI network group (120 patients transferred to another medical facility after ACS). We explored statistically relevant associations between sex and discharge therapy using the Pearson chi-square test in the UHCZG group, due to the completeness of this dataset. Results: The mean patient age in the UHCZG group was 44±7 years, and 148 (61.4%) were men. 139 (57.9%) patients had STEMI, 72 (30.0%) NSTEMI, and 29 (12.1%) had UA (Table 1, Figure 1). Female patients had a higher prevalence of hypothyroidism, lower diastolic blood pressure at admission and higher LDL values (Table 1). A significantly higher proportion of male patients were prescribed with angiotensin-converting enzyme inhibitors (ACEi) (82.4% versus 65.6%, p=0.003). There were no sex differences in the prescription of other cardiovascular drugs (Table 2). Conclusion: In a group of young patients with ACS, we found a statistically significant difference between male and female patients regarding the prescription of ACEi, despite a lack of significant difference in systolic blood pressure. Results similar to ours, regarding sex differences in optimal medical therapy, have been described in the literature, including young ACS patients.These results raise concerns regarding potentially negative consequences on the health of young women treated for ACS. [ABSTRACT FROM AUTHOR]

Background and Aim: There are still wide knowledge gaps in myocardial infarction with non-obstructive coronary arteries (MINOCA) - a heterogeneous entity seen in 1-10% of patients with acute coronary syndrome (ACS)1. The aim is to determine characteristics of MINOCA in the Croatian branch of the ISACS-CT registry, and compare them to age- and gender-matched patients with unstable angina (UA), non-ST-segment elevation myocardial infarction (NSTEMI) and ST segment elevation myocardial infarction (STEMI). Patients and Methods: The study included 2487 patients with ACS. MINOCA was defined by simultaneous cardiac troponin levels >0.014 ng/L, symptoms of ischemia or significant ST-T changes in the ECG, and an absence of coronary artery stenosis of ≥ 50% on angiography. Age and gender-matching was performed from the remaining cohort by randomly sampling patients from the UA, STEMI and NSTEMI subgroups, based on the mean age ± 5 years and the gender ratio of the MINOCA group. Results: MINOCA was seen in 2.5% (n=63) of the cohort, initially categorized as UA (37%), NSTEMI (48%) and STEMI (16%). Median age was 62 (53, 71) years, 56% male. After age- and gender-matching, there were 36 UA (10% of the UA cohort), 135 NSTEMI (15%) and 198 STEMI (16%) patients in the ACS control subgroups. MINOCA patients had a lower prevalence of diabetes, hypertension, dyslipidemia, chronic kidney disease and tobacco use as compared to UA and NSTEMI. MINOCA patients used less antiplatelets, beta-blockers and statins before hospitalization. MINOCA and STEMI subgroups had a high incidence of chest pain symptoms and a short time from symptom onset to hospitalization. In the first 24h of hospitalization, less MINOCA patients were treated with antiplatelets and statins, and at discharge, they were less frequently prescribed with antiplatelet drugs compared to UA and NSTEMI (Table 1). Inhospital mortality was low, with no deaths in MINOCA and UA patients, and 2 and 3 deaths in NSTEMI and STEMI, respectively. Conclusion: MINOCA patients are mainly categorized as UA and NSTEMI at presentation, but have less comorbidities, more pronounced symptoms of typical chest pain, a shorter time from symptoms to hospitalization, lower levels of statin and antiaggregation prescription at admission, and antiaggregation at discharge. In-hospital mortality confirms MINOCA as low risk, however, long-term registry follow-up is needed to learn about longer term outcomes. [ABSTRACT FROM AUTHOR]

Copyright of Cardiologia Croatica is the property of Croatian Cardiac Society and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction: Influenza affects millions worldwide every year. Although most cases are mild, severe complications can occur, including myocarditis1. Extracorporeal membrane oxygenation (ECMO) is a treatment option for patients with severe respiratory and/or cardiac failure. We present a case report of a patient with influenza-induced myocarditis and subsequent heart failure treated successfully with ECMO. Case report: 21-years-old male with no known history of medical illness presented to the Emergency Department at University Hospital Centre with fever, cough, and shortness of breath starting three weeks earlier. Chest X-ray showed pneumonia, PCR was COVID-19 negative but influenza positive. 12- lead electrocardiogram showed diffuse ST-segment elevation, cardiac biomarkers were elevated, and echocardiography verified reduced left ventricular ejection fraction (LVEF) of 44% with pericardial effusion. Patient was diagnosed with acute myopericarditis and pneumonia, admitted to hospital and started on broad-spectrum antibiotics. Four days later patient’s respiratory distress worsened requiring intubation and mechanical ventilation. Hemodynamic status deteriorated requiring noradrenaline and dobutamine support. Bedside echocardiogram showed akinesia of inferolateral and anterolateral wall with severely reduced LVEF. Due to escalation of support and hemodynamic instability, decision was made to initiate veno-arterial (V-A) ECMO support. During the procedure patient had cardiac arrest and was successfully resuscitated two times. Two days later, patient was transported to University Hospital Centre Zagreb. Echocardiography showed LVEF of 20% while the chest X-ray showed signs of severe congestion interpreted as ECMO lung oedema. Due to that, an immediate implantation of Impella was performed. However, as soon as Impella established adequate cardiac output, a severe case of Harlequin syndrome developed which required conversion of ECMO configuration to V-A-V that stabilized the situation and enabled conversion into V-V ECMO two days later. Following further stabilization, VV ECMO was removed two days later, Impella the following day, and patient was extubated. Cardiac recuperation was dramatic and cardiac MRI showed an LVEF of 57%. Patient was discharged home after 24 days. Conclusion: This case highlights the appropriate use of different mechanical circulatory support modalities guided by different imaging modalities for bridging a case of severe influenza-induced myocarditis from a cardiac arrest situation to successful hospital discharge. [ABSTRACT FROM AUTHOR]

Introduction: Pulmonary vein isolation (PVI) is a well-established method for treating paroxysmal and persistent atrial fibrillation (Afib) to maintain sinus rhythm. Left atrium size is an important factor which can determine rate/rhythm control strategy. Normal, mildly, and moderately increased left atrial volume index (LAVI) favors rhythm control. We sought to evaluate periprocedural characteristics and outcomes (freedom from Afib reccurence and effect on left atrium size) of Afib patients with severely enlarged left atria (LAVI > 48 mL/m²) who underwent cryo PVI in our institution. Patients and Methods: We analyzed data from our hospital’s PVI registry from February 2015 to November 2021. Patients with LAVI > 48 mL/m² prior to PVI were enrolled in the analysis. Follow up was performed through hospital’s information system to assess potential Afib reccurence and control LAVI. Results: Out of 611 patients, 222 had no information on left atrial size. Seventeen patients (2.78%) had LAVI > 48 mL/m² (mean 61 mL/m²; range 49-85 mL/m²). Patients were mostly men (n=10; 58.8%), in persistent Afib (n=10; 59.8%) and underwent PVI in sinus rhythm (n=12; 70.6%). Mean CHADS-VASc score was 2.11 (range 1-4). Fourteen patients had preserved ejection fraction (82.3%). Mean procedure time was 69.5 min and all PV were isolated in 15 patients (88.2%). There was no significant periprocedural complications (only two patients had transient phrenic nerve palsy). Three patients were lost to both clinical and echo follow up. Median follow up of was 11.5 months (range 5-29). Only two patients had Afib reccurence. LAVI measurement in follow up was available for seven patients and was statistically lower compared to index LAVI (44.6 mL/m² vs 55.7 mL/m²; p=0.03). Conclusion: Our results indicate that PVI can be a safe and effective method to maintain sinus rhythm and reduce LAVI in selected Afib patients with severely increased left atrium. [ABSTRACT FROM AUTHOR]

Introduction: In 2020 Croatia was stuck with two major earthquakes: on March 22nd with epicenter 7 km north of Zagreb city centre and on 29th December with epicenter 5 km south of city of Petrinja (5.5 and 6.2 degrees on the Richter scale respectively). The authors sought to investigate whether these events had an influence on characteristics and number of patients with cardiac chief complaints examined in the Emergency Departments (ED)1,2. Patients and Methods: Data on all emergency visits of patients with cardiac chief complaint examined in two University Hospital Centres (UHC) (Sestre Milosrdnice UHC, Zagreb and Zagreb UHC, Zagreb), two University Hospitals (UH) (“Sveti Duh UH, Zagreb and “Merkur” UH, Zagreb) and two regional hospitals (Sisak General Hospital, Sisak and Karlovac General Hospital, Karlovac) examined 7 days prior to earthquake, on the day of each earthquake, and during subsequent 6 days were collected. Results: In the examined period, there were 5575 ED visits (average age 66 years, female gender 45%), out of which in 1251 (22.4%) cases the chief complaint was cardiac. While in all patients seen after the earthquake only more often primary cardiac diagnosis found was non-anginal chest discomfort (28.8% vs 18.0%; p<0.001), when narrowed down the patients group to only the ones who were located within the 20 kilometers from the epicenter we found that there was significantly more patients with acute myocardial infarction (14.5% vs 22.8%; p= 0.028), acute elevation of blood pressure (10% vs 21.8%, p= 0.001), as well as more paroxysmal arrhythmias treated with electrocardioversion (0.9% vs 4.5%, p=0.022) (Table 1). Conclusion: In this study, increment in the frequency of cardiac emergencies was detected after a moderate earthquake in patients who were within 20 kilometers of the epicenter. They had significantly more often acute myocardial infarction, acute elevation of blood pressure, as well as paroxysmal arrhythmias treated with electrocardioversion. The health system should be prepared to treat a larger number of cardiac patients in difficult conditions after the earthquake. [ABSTRACT FROM AUTHOR]

Background: Cardiac imaging is essential in identifying structural changes in advanced heart failure (HF) enabling understanding of the underlying pathophysiology. Synchrotron radiation-based X-ray phase contrast imaging (X-PCI) is a novel non-destructive imaging modality that can provide high resolution three-dimensional (3D) visualization of cardiac tissue on the macro- and microstructural level, enabling analysis from the epi- to the endocardium, as well as collagen matrix reconstruction1,2. We aimed to explore the feasibility of utilising X-PCI for the imaging of full thickness myocardial samples and to explore microstructural features of cardiac tissue in different advanced HF aetiologies. Patients and Methods: Eight patients were included - two receiving a left ventricular assist device (LVAD) (LVAD group), and six undergoing heart transplantation (HTx) (HTx group). Aetiology of advanced HF in the LVAD group was ischaemic heart disease (IHD) and dilated cardiomyopathy (DCM). In the HTx group, 2 patients had IHD, while one patient had each of the following: DCM, restrictive cardiomyopathy, toxic cardiomyopathy, and adult congenital heart disease. Transmural tissue samples were obtained by left ventricular apical coring (LVAD group) and from the explanted hearts (HTx group). The tissue specimens were imaged by X-PCI at the Paul Scherrer Institute (Villigen, Switzerland) using a multi-scale setup resulting in low (LR) and high resolution (HR) imaging, at 5.8 and 0.65 μm effective pixel size, respectively. Imaging datasets were used to visualize morphological features and an opensource software (Ilastik) was used for semi-automatic collagen segmentation. Results: The images resulting from the apical coring samples are shown in Figure 1. X-PCI enabled multiscale exploration of transmural myocardial tissue samples providing 3D virtual histopathology. Additionally, reconstruction of the collagen matrix highlighting microstructural features and potential differences amongst different aetiologies of advanced HF was shown to be feasible without further sample preparation. Conclusion: X-PCI is a non-destructive, 3D imaging method that can extend the amount of information available from ex-vivo tissue analysis and potentially improve disease phenotyping. [ABSTRACT FROM AUTHOR]

Background: Graft rejection remains the most important complication after heart transplantation (HTx). Endomyocardial biopsy (EMB) is the gold standard in HTx follow-up, however, conventional histopathological (HP) analysis is limited by tissue damage during preparation, 2-dimensional (2D) analysis, and low inter-observer agreement in rejection grading. X-ray phase contrast imaging (X-PCI) has shown potential for non-destructive imaging of the myocardium, enabling high-resolution 3-dimensional (3D) analysis with fibrosis and fibre orientation quantification.¹ Methods and Design: GRAFT-XPCI is a multi-centric, prospective observational study aiming to prove non-inferiority of X-PCI in graft rejection diagnosis, vs. conventional HP (Figure 1). It will include ap-proximately 400 patients in standard post-HTx follow-up at 3 clinical centres: University Hospital Centre Zagreb, Dubrava University Hospital and Hospital Clinic Barcelona. Collected data will include EMB samples, patient history, laboratory, electrocardiogram (ECG), coronarography and echocardiographic data. EMB specimens will be initially imaged by X-PCI at the Paul Scherrer Institute (Villigen, Switzerland), producing digital 3D imaging datasets (at 0.65 um pixel resolution) for computational analysis, and then prepared for HP microscopy at the University of Zagreb School of Medicine. Three datasets will be generated for analysis - 2D X-PCI dataset, 3D X-PCI dataset, and 2D HP images. Acquired X-PCI images and HP slides will be diagnostically graded (ISHLT 2004. grading system)², comparatively assessed by at least two observers in a blinded fashion, further analysed in conjunction with gathered clinical data. Computer methods for the automatic and semi-automatic analysis of digital image datasets will be developed as an additional output. Conclusion: GRAFT-XPCI will: 1) compare X-PCI and conventional HP in graft rejection analysis, 2) enable insight into structural and pathophysiological processes in graft rejection after HTx, 3) extend the amount of information gained by EMB analysis. The development of new research tools and imaging protocols should widen future research of EMB analysis in various cardiac conditions. This study has been fully supported by the Croatian Science Foundation under the trial registration no. UIP-2020-02-5572. [ABSTRACT FROM AUTHOR]

Introduction: Human leukocyte antigen (HLA) sensitization is a barrier for successful heart transplantation (HTx), reduces the chance for compatible donors, prolongs waiting time to HTx, and increases the risk of acute rejection and cardiac allograft vasculopathy. Increasing prevalence of HLA sensitization and limitations of current desensitization strategies represent a great challenge in transplantation cardiology1,2. Rather than using pretransplant desensitization, in the last several years we have started peritransplant prophylactic therapy after careful selection of acceptable HLA antigen incompatibility. Therapy includes mechanical removal of antibodies, intravenous immunoglobulins (IVIg), and immunosuppressive drugs targeting antibody production³. We present a series of four HLA sensitized patients who underwent successful HTx at University Hospital Center Zagreb. Case 1: 58-year-old male patient with history of two cardiac surgeries (mitral valve replacement in 1993 and coronary artery bypass graft and mitral valve repair in 2009) underwent HTx in September 2018. Due to positive complement-dependent cytotoxicity (CDC) crossmatch and donor-specific antibodies (DSA, anti-HLA antibodies class I), seven procedures of plasmapheresis followed by intravenous immunoglobulins were conducted, starting on the first postoperative day. Initial endomyocardial biopsy (performed on twenty fourth postoperative day) showed no cellular (CMR) or antibody-mediated (AMR) graft rejection, and DSA showed decline in reaction sensitivity during first 6 post-transplant months. In March 2019 endomyocardial biopsy revealed signs of AMR (without clinical correlate) and three plasmapheresis procedures with intravenous immunoglobulins application were performed. Procedures were suspended due to leukopenia, influenza infection and Cytomegalovirus (CMV) viremia. Follow-up biopsy two months later showed no signs of AMR, with further decline in DSA reaction intensity. Treatment was continued with monthly extracorporeal photopheresis (ECP) procedures (25 cycles over the course of 2,5 years). One year after HTx a coronary angiography with optical coherence tomography imaging was performed and it showed signs of intimal hyperplasia. Due to that finding and continuously positive anti-HLA antibodies, everolimus was introduced as fourth immunosuppressant drug (together with tacrolimus, mycophenolate mofetil and prednisone). Latest patients’ check-up was in September 2022, there were no signs of heart failure, CMR or AMR, and DSA are still positive, but with low Luminex median fluorescence intensity (MFI) reactions. Case 2: 44-year-old female patient with end-stage heart failure due to left ventricular noncompaction cardiomyopathy (LVNC) underwent urgent HTx in December 2019. Due to positive anti-HLA DSA (with negative CDC crossmatch), desensitization protocol was performed (five plasmapheresis procedures, intravenous immunoglobulins and rituximab application). Since initial biopsy, performed one month after HTx, showed CMR (class 1R/2) and AMR, and DSA values showed MFI increase, pulse corticosteroid therapy followed by additional five cycles of plasmapheresis and intravenous immunoglobulins was applied. Control biopsy showed resolution of CMR and AMR. Patient attends regular check-ups (latest in September 2022) in which no signs of CMR or AMR were detected, and DSA are positive, but with low MFI reaction. Case 3: 60-year-old male patient with ischemic cardiomyopathy underwent HTx in February 2020. Due to positive anti-HLA DSA (with negative CDC crossmatch), desensitization protocol was performed (seven plasmapheresis procedures and intravenous immunoglobulins, followed by anti-CMV immunoglobulin application). Early post-transplantation period was marked with prolonged leukopenia, with no other adverse events. Patient attends regular check-ups (latest in September 2022) in which no signs of CMR or AMR were detected, and DSA remain continuously negative. Case 4: 54-year-old female patient underwent HTx in August 2022 due to end-stage heart failure caused by ischemic cardiomyopathy. Due to positive virtual crossmatch (but prospective CDC crossmatch negative) and anti-HLA DSA, desensitization protocol was started immediately, with first procedure of immunoadsorption prior to the transplantation. Another eight cycles of immunoadsorption were performed in initial postoperative days, followed by application of intravenous immunoglobulins, without adverse events. First endomyocardial biopsy, one month after transplantation, showed no signs of CMR or AMR, with no anti-HLA DSA in follow-up. Conclusion: Anti-HLA sensitization among heart transplant candidates is a growing problem with significant risk for posttransplant graft dysfunction and death. Strategy that includes virtual crossmatch and peritransplant desensitization therapies allow us to perform transplantation with good clinical outcome. [ABSTRACT FROM AUTHOR]

Background: Oral anticoagulation therapy for the prevention of thromboembolic complications of atrial fibrillation in patients awaiting heart transplantation (HTx) traditionally includes warfarin, and in the last few years it increasingly includes dabigatran. Anticoagulation must be reversed before the surgery. The possibility of rapid reversal of the anticoagulant effect of dabigatran with idarucizumab seems to represent an advantage¹. A comparison of bleeding complications between these two strategies has not been completely investigated. Patients and Methods: We did a retrospective analysis of bleeding complications during and immediately after HTx performed in University Hospital Center Zagreb in 15 patients divided into 3 groups: patients who were on warfarin prior to HTx, patients who were on dabigatran prior to HTx, and control patients without indication for anticoagulation therapy. Patients were mutually paired to eliminate the influence of other risk factors including age, gender, etiology of heart failure, renal function, as well as whether surgery was primary or after previous sternotomy. For the comparison of bleeding complications we measured the utilization of blood products (red blood cells, platelets, fibrinogen, fresh frozen plasma (FFP), prothrombin complex (PC) and the amount of thoracic drainage within the first 24 hours after the HTx. Results: There was no significant difference in the utilization of blood products as well as the amount of 24h thoracic drainage between these three groups (Table 1). Only 2/5 patients in the warfarin group were within the therapeutic INR range (2 pts below and 1 pts above the range). 24h thoracic drainage, FFP and PC consumption correlated with pretransplant INR (Table 2). Conclusion: Although there was no difference in the consumption of blood products and 24h thoracic drainage between patients who were on warfarin or dabigatran anticoagulation before HTx, it should be noted that the majority of patients on warfarin were not within the therapeutic INR range, and it was precisely the elevated INR that significantly correlated with the consumption of blood products and 24h thoracic drainage. It is necessary to conduct a study on a larger number of patients in order to find out whether the pre-HTx use of warfarin is equally safe and effective as the use of dabigatran, in terms of the perioperative bleeding. [ABSTRACT FROM AUTHOR]

Background: Diabetes mellitus (DM) is related to higher rates of complications after coronary revascularization. ¹ The efficiency of drug-coated balloon (DCB) percutaneous coronary intervention (PCI) has been shown for in-stent restenosis (ISR) and native small-vessel disease, however data on outcomes in DM is scarce.² The aim is to compare the incidence of target lesion restenosis at follow-up (FUP) coronary angiography in patients with and without DM receiving DCB PCI. Patients and Methods: The registry included patients undergoing a DCB PCI at the University Hospital Centre Zagreb from February 2011 to January 2022 (n=645). Patient demographics, comorbidities, pharmacotherapy, as well as data on the initial and FUP coronary angiography/PCI was collected. An FUP angiography was performed in 47% of patients (n=295), with a median FUP of 29 (interquartile range 8-41) months. Results: Data is shown in Table 1. The cohort was 75% male, mean age 65 ± 10 years. DM was present in 35% (n=223) of patients, equally in both sexes, and was associated with a history of myocardial infarction, PCI, coronary artery bypass grafting, stroke, as well as arterial hypertension, and renal insufficiency. No age difference was noted between groups. At initial PCI, more DM patients had multivessel coronary disease and ISR as the indication for DCB (DM vs non-DM: 41% vs 31%, p=0.023). After DCB, no group difference was noted in regard to the need for a bail-out PCI. FUP was performed in an equal percentage of patients in both groups (50% vs 45%, p=0.256), with no differences seen in the incidence of restenosis (18% vs. 17%, p=0.965), the need for target lesion PCI (15% vs. 12%, p=0.491), or the use of anti-anginal drugs. Conclusion: The findings of our single-centre analysis show that although DM is related to more advanced comorbidities it does not increase the risk of target lesion restenosis after DCB PCI. DCB PCI should be considered as a therapeutic option in candidate patients regardless of DM status. [ABSTRACT FROM AUTHOR]

Introduction: Transthyretin amyloidosis (ATTR) is a rare disease with heterogeneous symptoms and unfavorable outcomes unless diagnosed and treated in the early stage. Phenotypes and clinical presentations relate to underlying genetic variants (where genotype heterogeneity is well-known and related to endemic geographic regions) or the acquired form (wild type)1,2. The Croatian Transthyretin Cardiac Amyloidosis (CroATTR) Registry is designed as a national, longitudinal, non-interventional, and both retrospective and prospective ATTR registry. Methods: We aim to include patients with clinically proven hATTR-CM or wtATTR-CM according to the current guidelines, or family members with confirmed mutation of the TTR gene (regardless of the presence of cardiomyopathy). The registry will acquire basic demographic characteristics and results of genetic testing (for hATTR), followed by clinical work-up capturing patient demographics, quality of life questionnaires, medical and family history, data from 12-lead electrocardiogram (ECG), echocardiography, cardiac magnetic resonance imaging (cMRI) (with an emphasis on typical ATTR red flags), 99mTc- pyrophosphate scintigraphy, electromyoneurography, and myocardial biopsy, as available. The registry will follow diseasespecific outcomes: 1. overall survival, 2. cardiovascular mortality, 3. heart failure hospitalizations/unscheduled physician visits, 4. patient reported outcomes in the area of quality-of-life changes. The registry will also collect data on disease- specific treatments in our population: the proportion of patients treated with of guideline directed medical therapies (GDMT) for amyloidosis and heart and/or liver transplantation. The data will be captured at the time of inclusion of the patient in the registry (including retrospective data focusing on the time the diagnosis was first made) and will include prospective recurring visits. Data will be collected and managed using REDCap electronic data capture tools (the design of the database is shown on Figure 1). Conclusion: The CroATTR Registry will aggregate ATTR patients and allow further insights into the occurrence and natural course of disease. A particular emphasis will be made on the rare genetic mutation prevalent in our population, the utilization of guideline directed medical therapies and transplantation procedures. [ABSTRACT FROM AUTHOR]

Introduction: Implantable cardioverter-defibrillators (ICD) are a gold-standard therapy for prevention of sudden cardiac death (SCD).¹ Subcutaneous ICDs (S-ICD) provide a valuable alternative to conventional transvenous devices (TV-ICD) and can eliminate the risk of lead-related complications and lower risk of systemic infection in selected patients. Introduction of this technology involves higher economic burden and period of learning in emerging implantation centers. Patients and Methods: We analyzed data regarding all S-ICDs implanted since the introduction of the procedure in our institution in December 2021. Results: There were in total 7 patients (4 male and 3 female) with the median age 49 (28-64 years). All patients received S-ICD for primary prevention of SCD. Indications were as follows: ischemic cardiomyopathy (3 cases), hypertrophic cardiomyopathy (2 cases), non-ischemic cardiomyopathy (1 case) and catecholaminergic polymorphic ventricular tachycardia with concomitant cardiomyopathy (1 case). There were several different reasons for implantation of S-ICD rather than TV-ICD. Three patients suffered from severe kidney failure and two of them already had chronic dialysis catheters in situ. One patient had a previous infection of TV-ICD. Another patient with ischemic cardiomyopathy and repaired tetralogy of Fallot was not suitable for TV-ICD due to occlusion of left subclavian vein and probable need for future percutaneous implantation of pulmonary valve. In one patient S-ICD was a preferred option due to young age. First 6 cases were implanted with support of an experienced proctor. In one case the defibrillation test was repeatedly unsuccessful, and the patient required multiple external defibrillations. Reposition of the device was scheduled with optimal final result. No other complications were observed periprocedural or during follow-up. Conclusion: Subcutaneous ICDs have been safely and successfully implemented in our cardiology department without special surgical support. This experience will help to better address the need for prevention of SCD in special populations of patients. Although the total number of patients is still rather low, this could be improved by overcoming reimbursement issues. [ABSTRACT FROM AUTHOR]

Background: Late graft disfunction in patients after heart transplantation (HTx) is most often due to allograft rejection or allograft coronary artery disease but may also be due to infectious myocarditis or occasionally may occur without any documentable cause. Nonspecific allograft dysfunction may be caused by unrecognized myocarditis or even rejection because of unremarkable endomyocardial biopsy (EMB) specimens due to sampling error¹. Management of these patients is very challenging. Case report: We present 3 patients who developed nonspecific allograft dysfunction within 2 years after HTx. 38-year-old male presented with severe acute heart failure with left ventricle ejection fraction (LVEF) 30% two weeks after acute respiratory infection. 68-year-old male presented with a gradual reduction of functional capacity and LVEF 40% one month after COVID-19 infection. 55-year-old female was asymptomatic with LVEF 50%. She received COVID-19 messenger ribonucleic acid (mRNA) vaccine 5 months before. All patients had elevated biomarkers of cardiac injury (high sensitive Troponin-I and N-terminal pro b-type natriuretic peptide (NT-proBNP). Endomyocardial biopsy was negative for both cellular and antibody-mediated rejection but was also negative for histological signs of myocarditis. All patients were negative for donor-specific antibodies. Coronary angiography was normal. Cardiac magnetic resonance suggested a diagnosis of myocarditis. We have not diagnosed infectious cause in any of these patients. The findings were suggestive for clinically suspected myocarditis, and we decided to treat the patients with pulse steroid and intravenous immune globulins (IVIG). Patients showed significant improvement in graft function and so far have uneventful follow-up. Conclusion: It is difficult to recognize the cause of allograft dysfunction in some patients after HTx. It is crucial to exclude allograft rejection and vasculopathy. Post-transplant myocarditis is very unusual cause of graft failure, and EMB may be negative due to a lack of sufficient sensitivity considering the limited possibility of myocardial sampling. Although there are no controlled randomized data on steroid and IVIG treatment in these patients it seems that such therapy is safe and effective. [ABSTRACT FROM AUTHOR]

Introduction: Transcatheter left atrial appendage occlusion (LAAO) is a stroke prevention method for patients with atrial fibrillation (AF) and increased thromboembolic risk with a contraindication for oral anticoagulation (OAC) or with an elevated bleeding risk under chronic OAC.¹ This study aimed to assess patient characteristics, acute success rate, and periprocedural complication rate of transcatheter LAAO procedures in our institution. Patients and Methods: This single-center retrospective observational study included all patients who underwent transcatheter LAAO in our center from June 2021 until October 2022. Data were collected from hospital electronic medical records. Results: We evaluated all 18 consecutive patients (55.6% male, 72.2 ± 6.3 years) who underwent transcatheter LAAO. Patient characteristics and risk factors are shown in Table 1. The acute success rate was 88.9%, two proctored procedures were unsuccessful due to unfavorable anatomy. There were no procedure-related stroke, device embolization, or device-related thrombus. Procedure characteristics are shown in Table 2. Three patients (16.7%) developed postprocedural groin hematoma. One patient developed a femoral arteriovenous fistula and required surgical repair, while another patient developed hemodynamically irrelevant pericardial effusion. During follow-up, there were no thromboembolic complications, and one patient had a bleeding complication with dual antiplatelet therapy. Conclusion: Our data suggest that, since the introduction of this technology, transcatheter LAAO can be performed in our center with a good rate of acute success and low risk of periprocedural adverse events. [ABSTRACT FROM AUTHOR]

Introduction: The so called „zero fluoro” or „apron less” approach is getting more popular in the electrophysiology labs¹. The main concern of this strategy is its safety. We aimed to demonstrate the feasibility of zero-fluoro approach for the repeat atrial fibrillation (AF) procedures after initial cryoballoon ablation (CB). Patients and Methods: We have performed a retrospective study on patients that have undergone repeat pulmonary vein isolation (PVI) procedures in our institution since we started the zero-fluoro program in 2020. All patients received CB ablation for the initial procedure. Procedures were performed under conscious sedation with the help of intracardiac echo (ICE) and 3D mapping system, without the use of fluoroscopy. Right-sided femoral vein was used for the two introducers. A single transseptal puncture was performed guided by ICE. Steerable sheath was used and high-density voltage map of left atrium (LA) was created to evaluate the pulmonary vein (PV) reconnections. Contact-sensing radiofrequency ablation (RF) ablation catheters were used to reisolate the reconnected veins and in the case of no reconnections, posterior wall isolation was performed. Results: We have analyzed in total 38 patients (74% male, 59.3±0.3 years old), 53% of which suffered from paroxysmal AF. The mean left ventricular ejection fraction was 61.6±7.0% and mean LA diameter was 42.0±5.2 mm. In two (5.2%) patients RF energy was required to cross the intraatrial septum. In one patient (2.7%) conversion to fluoroscopy was required because of demanding transseptal puncture. The mean procedure time was 98.1.3±26.4 min and the mean RF time was 821 sec±420 sec. The mean of 1.25±0.893 veins were reconnected per patient and 10 patients (26.3%) did not have PV reconnections. In all patients successful PV/PW isolation was performed confirmed by entry and exit block. No periprocedural complications were observed. Conclusion: In our cohort of patients, zero-fluoro approach for repeat PVI procedures ablation proved to be feasible and safe. Conversion to fluoroscopy was needed infrequently for more difficult transseptal procedures. [ABSTRACT FROM AUTHOR]

Background: Right ventricular (RV) failure is a common complication of left ventricular assist devices (LVAD). We describe two cases of durable LVAD carriers requiring acute RV mechanical support provided using the ProtekDuo (LivaNova, IT) cannula, implanted via the right jugular internal vein, bypassing the RV by draining blood from the right atrium to an extracorporeal blood pump (Rotaflow pump, Maquet, DE) and returning it to the pulmonary artery (Figure 1). Case report 1: A 37-year-old male following LVAD implantation in 2016 due to dilated cardiomyopathy, was diagnosed with chronic RV failure in 2018. During a subsequent episode of of acute RV failure parenteral furosemide, dobutamine and intermittent levosimendan were started. Due to ensuing cardiogenic shock, veno-arterial extracorporeal membrane oxygenation (VA-ECMO) was placed. Three days later, an upgrade to a paracorporeal RVAD (p-RVAD) by placement of a ProtekDuo cannula and Rotaflow pump providing a flow of 4.15 litres/minute was performed. An improvement of hemodynamic parameters was obtained with the p-RVAD, but while awaiting the high-urgent heart transplantation, multiorgan failure and repetitive infections ensued, leading to the patients’ death. Case report 2: In April 2020, a 28-year-old male earlier diagnosed with dilated cardiomyopathy was admitted for acute heart failure. Echocardiography showed a predominant left ventricular cardiomyopathy with significantly reduced LV ejection fraction of 15%. One week after admission, ventricular fibrillation occurred, terminated by implantable cardioverter-defibrillator. Due to hemodynamic compromise, dobutamine and norepinephrine were started, but VA-ECMO was required soon thereafter. Three days later, a durable LVAD (HeartMate 3, Abbott, USA) implantation was performed, however the patient was not weanable from cardiopulmonary bypass due to acute RV failure, and promptly received a p-RVAD with the ProtekDuo cannula. Two weeks later, the p-RVAD was successfully weaned and he was discharged a month later and is currently in regular follow-up. Conclusion: We present two cases of acute and chronic RV failure in LVAD carriers. In both cases, the ProtekDuo cannula enabled acute RV support. Early institution of RV mechanical circulatory support, when needed, should improve patient outcomes. [ABSTRACT FROM AUTHOR]

Background: Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is widely used in refractory cardiogenic shock and cardiac arrest but is characterized by increased left ventricular (LV) afterload and consequent development of pulmonary oedema (ECMO lungs). The ProtekSoloTM (LivaNova, IT) cannula is inserted via the right femoral vein to the left atrium, by a trans-septal puncture (under the guidance of transesophageal echocardiography and fluoroscopy). This bypasses the LV by draining blood from the left atrium to a paracorporeal pump (eg Rotaflow pump (Maquet, DE)) and returning it via a femoral artery cannula, thus providing direct unloading of LV. We aimed to demonstrate our experience with the paracorporeal LV assist device using the ProtekSolo cannula and Rotaflow pump (PSp-LVAD). Patients and Methods: 7 adult patients underwent PSp-LVAD placement in UHC Zagreb from January to December 2020. We divided the patients in two groups: those who required PSp-LVAD to treat ECMO lungs (n=4) and those who received PSp-LVAD implantation prior to developing ECMO lungs (n=3). In addition to the description of the treated patients, we also assessed 30-day all-cause mortality. Results: The baseline characteristics of patients are shown in Table 1. All patients were male, mean age 56±9.3 years. 57.1% of patients underwent PSp-LVAD placement due to worsening of chronic heart failure and 42.9% due to acute coronary syndrome. Concurrent infection was present in 57.1% of patients. 71.4% were first on VA-ECMO support, of those 80% developed ECMO lungs. Laboratory tests (Figure 1) show improvement in kidney and liver function after PSp-LVAD placement. Outcomes are shown in Table 2; patients in prophylactic group have lower observed 30-day mortality rate (33% vs 75%) and longer VA-ECMO support duration due to lower mortality. Besides 2 patients who are still in active treatment, all others died during initial hospitalization due to infective complications, predominantly those that had a concurrent infection upon institution of the PSp-LVAD. Conclusion: Pulmonary edema (ECMO lungs) due to increased LV afterload is a major complication of VA-ECMO. Prophylactic LV unloading by PSp-LVAD seems associated with lower 30-days mortality. [ABSTRACT FROM AUTHOR]

Introduction: Data on heart transplant (HTx) patients and infection with acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are very limited. There is significant heterogeneity in the clinical presentation. Immunosuppression-related issues are of the main concern because of an increased risk for viral replication and superimposed infections. There is no evidence-based recommendation for the management of these patients. Some authors suggest modification in immunosuppression, i.e. discontinuation of mycophenolate mofetil (MMF) and calcineurin inhibitor (CNI) reduction in patients with more severe clinical presentation. Patients and Methods: This is a case series of 5 HTx recipients from our center who tested positive for COVID-19 infection and were treated in different COVID-19 specialized units. Results: There were 4 male and one female patients, 62-75 years old. Four of them were symptomatic and hospitalized, while one remained self-quarantined at home. The clinical presentation was mild to moderate, with symptoms including mild fever, dyspnea, and myalgia. X-ray signs of pneumonia were present in 3 patients, but none needed ICU care nor mechanical ventilation. Both a reduction of CNI dose with lower target serum concentration and MMF was discontinued in all patients. One patient was treated with hydroxychloroquine, one with remdesivir and one with steroid therapy. Antibiotics prophylaxis was administered in 2 patients. None of the patients experienced overt graft rejection and all patients have successfully recovered (Table 1). Conclusion: Lacking any evidence-based recommendation for the treatment of HTx patients infected with SARS-CoV-2, we are challenged to modify maintenance immunosuppression carefully balancing between the risk of uncontrolled viral replication with a superimposed infection on one side, and the increased risk of graft rejection on the other side. Further studies are needed to determine the optimal management of COVID-19 infection in these patients. [ABSTRACT FROM AUTHOR]

Background: Venoarterial extracorporeal membrane oxygenation (VA-ECMO) is increasingly used in patients during cardiac arrest and cardiogenic shock and is associated with increased survival rate. Since mortality on ECMO is still rather high, SAVE (Survival after Veno-Arterial ECMO) score can be used to predict survival from refractory cardiogenic shock requiring ECMO. Patients and Methods: We performed a retrospective analysis of 121 patients (78% male) who underwent VA-ECMO implantation in our Department from January 2011 till November 2020 (Figure 1 and Table 1). Results: Median age was 58 years with 21% of patients older then 65 years. Median of ECMO duration was 6 days. The most common causes of cardiogenic shock were acute myocardial infarction and cardiomyopathy (53% and 37%, respectively) (Figure 2), and 37% patients were implanted during cardiopulmonary resuscitation (eCPR). Overall survival on ECMO support was 59%, but in patients after CPR only 34%. Furthermore, of all patients, 34% were successfuly weaned and the rest who survived continued on advanced heart failure therapies (Figure 3), but overall survival in follow-up was only 26%. Median SAVE score was -8 with significantly less negative values in patients younger than 65 and treated after 2015. Also, patients treated before 2015 had significantly higher values of creatinine, free hemoglobine and international normalized ratio (INR) and their survival rate was only 39%, in comparison to those who were implanted after 2015 whose survival rate was 62%. [ABSTRACT FROM AUTHOR]

Background: A plethora of studies have proven the increase in cardiovascular risk associated with smoking in all age groups1, including the one at the focus of this study - the young2,3. With regard to the total number of coronary arteries (CA) with significant stenoses, one might expect current smokers to have more affected CA than non- and former smokers. Aim: To explore the relationship between smoking status and the total number of CA with significant stenoses in a young ST-segment elevation myocardial infarction (STEMI) population. Patients and Methods: Data were attained from medical records of 147 patients (mean age 43.9±6.5 years) hospitalized with STEMI at the University Hospital Centre Zagreb from January 2012 to October 2018, with a cut-off age at 45 years for men (n = 93) and 55 years for women (n = 54). Patients were divided in 2 groups based on smoking status - non- and former smokers (N = 29 (20%), with former smokers making up 9/29 or 31% of the group), and current smokers (N = 118 (80%)). To evaluate whether smoking status was associated with a higher total number of CA with significant stenoses, Pearson's chi-squared test was performed. During post hoc testing, the p value was adjusted to maintain the familywise error rate at 0.05 (p = 0.008) and compared to p values of each subgroup. Results: The two groups had no significant differences in baseline characteristics (Table 1). In both groups, the majority of patients (58.6% vs. 74.6%) had only one affected CA, followed by two (27.6% vs. 19.5%) and three (13.8% vs. 5.9%) CA. Pearson's chi-squared test showed no statistically significant difference in the total number of affected CA between the two groups (p = 0.176). Post hoc testing confirmed statistically insignificant associations in all subgroups (p > 0.008, Table 2). In multiple regression (F (2, 144) = 9.27, p < 0.001, R2 adjusted = 0.10), age (B = 0.03, p = 0.001) and family history for cardiovascular disease (B = 0.30, p = 0.003) remained associated with the number of affected CA. Conclusion: Within our dataset of young patients with STEMI, a very high proportion (reaching 80%) were active smokers. A similar total number of CA was affected by significant stenoses, regardless of smoking status. However, caution should be exercised when interpreting these results that require additional input on comorbidities and risk factors enabling conclusions to be drawn from a broader context. [ABSTRACT FROM AUTHOR]

Background and Aim: The relevance of dual antiplatelet therapy (DAPT) in acute ST-segment elevation myocardial infarction (STEMI) is well-established (aspirin and P2Y12 inhibitors).1 The role of glycoprotein (GP) IIb/IIIa inhibitors in clinical practice is not completely defined. Administration in the event of thrombotic complications is considered reasonable, although there is no evidence for routine use in primary percutaneous coronary intervention (pPCI). The aim was to analyze early outcomes of STEMI patients (pts) in the Croatian branch of the ISACS-CT (International Registry of Acute Coronary Syndromes in Transitional Countries) registry, depending on received antiaggregation therapy. Patients and Methods: Data were gathered retrospectively from pts hospitalized between January 2012 to October 2017. The study included 2503 pts with acute coronary syndrome, from which 48.9% (n=1224) were diagnosed with STEMI. The patients were divided into 4 groups depending on administered antiaggregation therapy. Results: For 7.8% (n=96) pts antiaggregation therapy data were missing, and 5.8% (n=71) were not treated with DAPT. Remaining 1057 (86.4%) pts were analyzed. Aspirin was administered in 95% of pts in the first 24 hours. 41.9% (n=443) of pts were additionally treated with clopidogrel, 16.1% (n=170) with ticagrelor, 28.6% (n=302) with clopidogrel and eptifibatide, and 13.4% (n=142) with ticagrelor and eptifibatide (Table 1). The groups did not differ in comorbidities, while pts receiving eptifibatide had lower systolic blood pressure on admission. Patients treated with eptifibatide were more frequently male, smokers, of younger age, had more thrombotic complications seen on coronary angiography (predominantly distal embolisation and "no-reflow" phenomenon) and lower in-hospital mortality. In a multivariable regression model adjusted for age, gender, hypertension, diabetes, and pPCI, increasing age (OR=1.1), diabetes (OR=1.9) and pPCI (OR=0.5) remained relevant to in-hospital mortality. Conclusion: STEMI patients that are young, male and smokers are more frequently treated with eptifibatide, likely due to a higher burden of thrombotic complications. Unlike the choice of antiaggregation therapy, increasing age, diabetes and non-invasive management of STEMI were associated with in-hospital mortality. [ABSTRACT FROM AUTHOR]

Background: Decrease in platelet count following the induction with polyclonal anti-thymocyte globulin (ATG) is deemed as an adverse event, while decrease in lymphocyte count represents a therapeutic goal1. Still, the effect on platelets may represent an important part of ATG anti-rejection mechanisms. Patients and Methods: This was a retrospective single-center study of consecutive HTx (heart transplantation) patients (pts) from February 2010 to February 2018 in University Hospital Centre Zagreb. All pts received rATG (Thymoglobulin®) 1.5 mg/kg daily during the first 5 days. Complete blood count with differential was assessed on days 0, 7 and 14 after HTx. The incidence of cellular-mediated rejection (ACR) was monitored for two years after HTx. ACR was classified according to ISHLT classification from 1990 and expressed as ACR of grade 1B or higher (≥1B). Results: A total of 159 pts were transplanted. Median age was 55 years (IQR, 47-62 years), 76% were male. A total of 27 pts (17 %) experienced ACR ≥1B during 24 months. Pts with ACR of grade ≥1B had higher platelet count on day 7 (145 vs 104 x 103/μL, p<0.001). They also had higher the absolute lymphocyte count (ALC) on the same day, but this did not reach statistical significance (162 vs 130 x 103/μL, p=0.19) and there was no correlation between ALC and platelet counts on day 7 (Pearson's correlation coefficient was 0.064, p=0.459). Conversely, more rejection was observed in pts with higher ALC on day 14 (326 vs 190 x 103/μL, p=0.035), with a trend towards statistical significance in the relationship with higher platelet count (210 vs 199 x 103/μL, P=0.076). In the univariate analysis, higher platelet count on day 7, younger recipient age and negative pre-transplant Cytomegalovirus (CMV) IgG serology were found as predictors of the ACR ≥1B in the first 2 years after HTx (Table 1). In multivariable model, platelet count on day 7 and pre-transplant CMV serostatus were independent predictors of rejection. ROC analysis of the aforementioned model showed a satisfying AUC of 0.75. Conclusion: Decrease in platelet count following the induction with rATG is strongly related to less graft rejection that is independent from the lymphodepleting effect. This indicates the importance of platelet involvement in anti-rejection mechanisms of ATG induction, and consequently a possible rationale for targeting platelets in future immunosuppressive regimens. [ABSTRACT FROM AUTHOR]

Introduction: A life-threatening hyperinflammatory condition occurring several weeks after primary infection with SARS-CoV-2 that can include severe acute heart failure has been reported in children in early 2020. Later on, a condition with similar characteristics has also been reported in adults.1,2 Case report: 26-year-old male patient with obesity and arterial hypertension presented to the emergency department with 3 days history of fever, chills, dyspnea, exercise intolerance, headache, dry cough, nasal discharge and diarrhea approximately six weeks after he has been diagnosed with mild COVID-19. Initial blood tests showed markedly elevated laboratory inflammatory markers. CT scan showed enlarged lymph nodes in the neck and small areas of residual ground-glass opacities in the lungs. Pulmonary thromboembolism was ruled out. He was admitted to the infectious disease clinic and was started on cloxacillin, ceftriaxone, antipyretics and appropriate rehydration. On the third day of hospital treatment, the patient complained of chest and neck pain and severe dyspnea. His general condition deteriorated rapidly, and he was transferred to the intensive care unit due to the development of cardiogenic shock. Inotropic and vasopressor support was initiated. Echocardiography showed mildly dilated left ventricle with severe impairment of global systolic function (LVEF 20 %). High-sensitivity troponin I and NT-proBNP were markedly elevated with a peak concentration of 792 and 18200 ng/l, respectively. Therefore, the patient was transferred to the tertiary center coronary care unit (CCU). Pulse steroid therapy and intravenous immunoglobulin were immediately initiated, while heart failure therapy was gradually introduced in the following days. Seven days after admission to CCU, multiparametric cardiac magnetic resonance imaging (MRI) revealed preserved LVEF with diffusely prolonged myocardial T1 relaxation time and T2 relaxation time, confirming myocardial injury and edema, respectively. There was no late gadolinium enhancement (Figure 1). Updated Lake-Louise criteria for myocarditis have been fulfilled.3 The following criteria for multisystem inflammatory syndrome in adults (MIS-A) were met: age over 21 years, a positive test result for previous SARS-CoV-2 infection, documented fever >38.0°C for ≥24 hours, laboratory evidence of inflammation, involvement of cardiovascular and gastrointestinal system, and severe illness requiring hospitalization. Conclusion: This case indicates that there is a vast diversity of clinical presentation and underlying mechanisms of COVID-19 and post-COVID-19 syndromes with myocardial injury. Recently described MIS-A is a rare but potentially life-threatening complication of previous SARS-CoV-2 infection. Clinicians should be aware of this syndrome in order to recognize it on time and start with appropriate treatment. [ABSTRACT FROM AUTHOR]

Copyright of Cardiologia Croatica is the property of Croatian Cardiac Society and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Cardiologia Croatica is the property of Croatian Cardiac Society and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Cardiologia Croatica is the property of Croatian Cardiac Society and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: In our previous research1 we have shown 2D analysis of regional longitudinal peak systolic strain (LPSS) to be superior to visual assessment of regional wall motion abnormalities (RWMA) in detection of ischemiainduced loss of myocardial contractility due to non-ST elevation acute coronary syndrome (NSTE-ACS).2,3 The reduction of LPSS in basal segments in patients with arterial hypertension (AH) is well documented. The aim of this study was to assess the impact AH has on the accuracy of regional analysis in predicting the localization of significant stenosis in NSTE-ACS. Methods: We performed a retrospective analysis of patients admitted to University Hospital Centre Zagreb from January 2013 till December 2015 due to NSTE-ACS. Exclusion criteria were no coronary angiography, absence of ECHO, and prior coronary artery disease. Total of 123 patients (62±12 years, 68% male) were included. 4 blinded clinicians performed regional LPSS analysis using 18-segment model, while RWMA, interpreted by clinician performing the echo, were categorized according to the wall motion score guidelines. Results: Significant correlation between flow limiting stenosis (>70% narrowing on angiography), worse RWMA and a decrease of regional LPSS in basal segments was found for all 3 coronary vessels (Table 1). Patients with AH (73%) showed a lower regional LPSS and worse RWMA in all basal segments, with only lateral and posterior ones varying significantly (Figure 1). However, regression analysis accounting for AH as a covariant, showed the regional changes in basal segments to be a sole result of coronary disease (Table 2). AH was found to have no impact on reliability of LPSS and RWMA in predicting the localization of significant stenosis in NSTE-ACS (average method sensitivities: 59% vs 38%). Conclusion: Changes in regional myocardial contractility, detected by either LPSS or RWMA, in patients with NSTEACS should be attributed to coronary disease irrespectively of the presence of AH. [ABSTRACT FROM AUTHOR]

Copyright of Cardiologia Croatica is the property of Croatian Cardiac Society and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Cardiologia Croatica is the property of Croatian Cardiac Society and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Cardiologia Croatica is the property of Croatian Cardiac Society and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Cardiologia Croatica is the property of Croatian Cardiac Society and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Cardiologia Croatica is the property of Croatian Cardiac Society and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Cardiologia Croatica is the property of Croatian Cardiac Society and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Cardiologia Croatica is the property of Croatian Cardiac Society and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)