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Introduction: The utility of ablation index (AI) to guide ventricular tachycardia (VT) ablation in patients with structural heart disease is unknown. The aim of this study was to assess procedural characteristics and clinical outcomes achieved using AI‐guided strategy (target value 550) or conventional non‐AI‐guided parameters in patients undergoing scar‐related VT ablation. Methods: Consecutive patients (n = 103) undergoing initial VT ablation at a single center from 2017 to 2022 were evaluated. Patient groups were 1:1 propensity‐matched for baseline characteristics. Single lesion characteristics for all 4707 lesions in the matched cohort (n = 74) were analyzed. The impact of ablation characteristics was assessed by linear regression and clinical outcomes were evaluated by Cox proportional hazard model. Results: After propensity‐matching, baseline characteristics were well‐balanced between AI (n = 37) and non‐AI (n = 37) groups. Lesion sets were similar (scar homogenization [41% vs. 27%; p =.34], scar dechanneling [19% vs. 8%; p =.18], core isolation [5% vs. 11%; p =.4], linear and elimination late potentials/local abnormal ventricular activities [35% vs. 44%; p =.48], epicardial mapping/ablation [11% vs. 14%; p =.73]). AI‐guided strategy had 21% lower procedure duration (−47.27 min, 95% confidence interval [CI] [−81.613, −12.928]; p =.008), 49% lower radiofrequency time per lesion (−13.707 s, 95% CI [−17.86, −9.555]; p <.001), 21% lower volume of fluid administered (1664 cc [1127, 2209] vs. 2126 cc [1750, 2593]; p =.005). Total radiofrequency duration (−339 s [−24%], 95%CI [−776, 62]; p =.09) and steam pops (−155.6%, 95% CI [19.8%, −330.9%]; p =.08) were nonsignificantly lower in the AI group. Acute procedural success (95% vs. 89%; p =.7) and VT recurrence (0.97, 95% CI [0.42–2.2]; p =.93) were similar for both groups. Lesion analysis (n = 4707) demonstrated a plateau in the magnitude of impedance drops once reaching an AI of 550–600. Conclusion: In this pilot study, an AI‐guided ablation strategy for scar‐related VT resulted in shorter procedure time and average radiofrequency time per lesion with similar acute procedural and intermediate‐term clinical outcomes to a non‐AI‐guided approach utilizing traditional ablation parameters. [ABSTRACT FROM AUTHOR]

Aims: Tachycardia‐induced cardiomyopathy (TCM) represents a partially reversible type of cardiomyopathy (CM) that is often underdiagnosed and cardiac chamber remodelling in TCM remains incompletely understood. We aim to explore differences in the dimensions of the left ventricle and functional recovery in patients with TCM compared with patients with other forms of CM. Methods and results: We identified patients with reduced ejection fraction (≤50%) and/or atrial fibrillation or flutter with a left ventricular ejection fraction that improved from baseline (≥15% in left ventricular ejection fraction at follow‐up or normalization of cardiac function with at least 10% improvement). Patients were then divided into two groups: (A) TCM patients and (B) patients with other forms of CM (controls). Two hundred thirty‐eight patients were included (31% female, 70 years median age), 127 patients had TCM, and 111 had other forms of CM. Patients with TCM did not significantly improve indexed left ventricular volume (LVEDVI) after treatment (60 [45, 84] mL/m2 versus 56 [45, 70] mL/m2, P = ns) compared with controls (67 [54, 81] mL/m2 versus 52 [42, 69] mL/m2, P < 0.001). Patients with TCM patients had significantly worse fractional shortening at baseline than controls (15.5 [12, 23] vs. 20 [13, 30], P = 0.01) and higher indexed left atrial volume (LAVI) at baseline than controls (48 [37, 58] vs. 41 [33, 51], P = 0.01) that remained dilated at follow‐up (follow‐up LAVI 41 [33, 52] mL/m2). Good predictors of TCM were: normal LVEDVI (LVEDVI < 58 mL/m2 (M) and < 52 mL/m2 (F)) (odds ratio [OR] 5.2; 95% confidence interval [CI] 2.2–13.3, P < 0.001), fractional shortening < 30% (OR 3.5; 95% CI 1.4–9.2, P = 0.009), LAVI >40 mL/m2 (OR 3.4; 95% CI 1.6–7.3, P = 0.001) and normal wall thickness left ventricle (OR 3.2; 95% CI 1.4–7.8, P = 0.008). 54% of patients with TCM demonstrated diastolic dysfunction at follow‐up, without differences from controls (54% vs. 43%, P = ns). 21% of patients with TCM showed persistent heart failure symptoms at follow‐up compared with 4.5% of controls, P = 0.004. Conclusions: TCM patients have a specific pattern of functional recovery with persistent remodelling of the left atria and left ventricle. Several echocardiographic parameters might help identify TCM before treatment. [ABSTRACT FROM AUTHOR]

Background: Persistent atrial fibrillation (AF) is associated with high recurrence rates of AF and atypical atrial flutters or tachycardia (AFT) postablation. Laser balloon (LB) ablation of the pulmonary vein (PV) ostia has similar efficacy as radiofrequency wide area circumferential ablation (RF‐WACA); however, an approach of LB wide area circumferential ablation (LB‐WACA) may further improve success rates. Objective: To evaluate freedom from atrial tachyarrhythmia (AFT/AF) recurrence postablation using RF‐WACA versus LB‐WACA in persistent AF patients. Methods: This was a retrospective multicenter study. Patients were followed for up to 24 months via office visits, Holter, and/or device monitoring. The primary endpoint was freedom from AFT/AF after a single ablation procedure. Secondary endpoints included freedom from AF, freedom from AFT, first‐pass isolation of all PVs, and procedural complications. Results: Two hundred and four patients were studied (LB‐WACA: n = 103; RF‐WACA: n = 101). Patients' baseline characteristics were similar except patients in the RF‐WACA group were older (64 vs. 68, p =.03). First‐pass isolation was achieved more often during LBA (LB‐WACA: 88% vs. RF‐WACA 75%; p =.04). Procedure (p =.36), LA dwell (p =.41), and fluoroscopy (p =.44) time were similar. The mean follow‐up was 506 ± 279 days. Sixty‐six patients had arrhythmic events including 24 AFT and 59 AF recurrences. LB‐WACA group had higher arrhythmia‐free survival (p =.009) after single ablation procedures. In the multivariate Cox regression model, RF‐WACA was associated with a higher recurrence of AFT compared with LB‐WACA (Adjusted HR 3.16 [95% CI: 1.13–8.83]; p =.03). Conclusions: LB‐WACA was associated with higher freedom from atrial arrhythmias mostly driven by the lower occurrence of AFT compared with RF‐WACA. [ABSTRACT FROM AUTHOR]

Background: Ablation Index (AI) is a multiparametric quality marker to assess the durability of radiofrequency (RF) lesions. The comparative effectiveness and safety of AI versus time‐based energy dosing for ablation of ventricular arrhythmias are unknown. Objective: We compared AI and time‐based RF dosing strategies in the left ventricles (LVs) of freshly harvested porcine hearts. Methods: Ablation was performed in vitro with an open‐irrigated ablation catheter (Thermocool ST/SF), 40 W, contact force 10–15 g. Tissue samples were stained in triphenyltetrazolium chloride for the measurement of lesion dimensions. Results: A total of 560 lesions were performed (AI‐group: [n = 360]; time‐group: [n = 200]). Using normal saline (NS) (n = 280), growth in lesion depth slowed after 30 s and AI > 550 in comparison to width, volume, and magnitude of impedance drops which continued to increase with longer RF duration. Risk of steam pop (SP) was higher for RF > 30 s (RF < 30 s:1 SP [2.5%] vs. RF > 30 s: 15 SP [25%]; p =.002) or AI targets >550 (AI: 350–550: 2 SP [2%] vs. AI 600–750: 15 SP [19%]; p =.001). Using half‐normal saline (HNS) (n = 280), lesion dimension and impedance drops were larger and growth in lesion depth slowed earlier (AI: 500). Risk of SPs was higher above AI 550 (AI: 350–550: 7 [7%] SPs vs. AI 600–750: 28 [35%] SPs; p <.00001). While codependent variables, correlation between AI and time was modest‐to‐strong but decreased with longer RF duration. Conclusion: In this ex vivo study, AI was a better predictor of lesion dimensions than ablation time and magnitude of impedance drop in the LV using NS and HNS irrigation. AI targets above 550 led to a higher risk of SPs. Future trials are required to verify these findings. [ABSTRACT FROM AUTHOR]

COVID‐19 has significant case fatality. Glucocorticoids are the only treatment shown to improve survival, but only among patients requiring supplemental oxygen. WHO advises patients to seek medical care for "trouble breathing," but hypoxemic patients frequently have no respiratory symptoms. Our cohort study of hospitalized COVID‐19 patients shows that respiratory symptoms are uncommon and not associated with mortality. By contrast, objective signs of respiratory compromise—oxygen saturation and respiratory rate—are associated with markedly elevated mortality. Our findings support expanding guidelines to include at‐home assessment of oxygen saturation and respiratory rate in order to expedite life‐saving treatments patients to high‐risk COVID‐19 patients. [ABSTRACT FROM AUTHOR]

Background: Radiofrequency (RF) ablation with half‐normal saline (HNS) has shown promise as a bail‐out strategy following failed ventricular tachycardia ablation using standard approaches. Objective: To use a novel infrared thermal imaging (ITI) model to evaluate biophysical and lesion characteristics during RF ablation using normal saline (NS) and HNS irrigation. Methods: Left ventricular strips of myocardium were excised from fresh porcine hearts. RF ablation was performed using an open‐irrigated ablation catheter (Thermocool ST/SF) with NS (n = 75) and HNS (n = 75) irrigation using different power settings (40/50 W), RF durations (30/60 s), contact force of 10–15 g, and flow rate of 15 ml/min. RF lesions were recorded using an infrared thermal camera and border zone, lethal, 100° isotherms were matched with necrotic borders after 2% triphenyltetrazolium chloride staining. Lesion dimensions and isotherms (mm2) were measured. Results: In total, 150 lesions were delivered. HNS lesions were deeper (6.4 ± 1.1 vs. 5.7 ±0.8 mm; p =.03), and larger in volume (633 ± 153 vs. 468 ± 107 mm3; p =.007) than NS lesions. Steam pops (SPs) occurred during 19/75 lesions (25%) in the NS group and 32/75 lesions (43%) in the HNS group (p =.34). Lethal (57.8 ± 6.5 vs. 36.0 ± 3.9 mm2; p =.001) and 100°C isotherm areas (16.9 ± 6.9 vs. 3.8 ± 4.2 mm2; p =.003) areas were larger and were reached earlier in the HNS group. Conclusions: RFA using HNS created larger lesions than NS irrigation but led to more frequent SPs. The presence of earlier lethal isotherms and temperature rises above 100°C on ITI suggest a potentially narrower therapeutic‐safety window with HNS. [ABSTRACT FROM AUTHOR]

Background: Atrial fibrillation (AF) is a growing healthcare burden, for which pulmonary vein isolation (PVI) using cryoballoon (CB) or radiofrequency (RF) represent attractive therapies. Women are at higher risk of recurrence after AF ablation and present a specific complications profile. Therefore, a systematic catheter‐specific assessment of pulmonary vein isolation is urgently needed in women. Objective: Systematically assessing the sex‐specific efficacy/safety of CB vs RF ablation. Methods: We performed a structured database search of the scientific literature for randomized controlled trials (RCTs) and observational prospective studies (OPS) comparing CB and RF ablation efficacy at 1 year. We investigated the reporting of sex‐specific analyses and assessed the comparative sex‐specific efficacy, safety and procedural characteristics of CB vs RF using random‐effect meta‐regression accounting for the proportion of enrolled women. Results: Twenty‐three studies were included (18 OPS and 5 RCTs) for a total of 13 509 patients. Sex‐specific outcomes by ablation device were reported in two and sex‐specific regression in four studies, none of which took the ablation device into account. Meta‐regression accounting for the proportion of enrolled women showed no significant difference in outcomes between RF or CB. Conclusion: The sex‐specific reporting in trials comparing CB to RF is extremely low. A quantitative meta‐regression using the percentage of enrolled women as sex‐specific indicator did not show any difference between CB and RF but acknowledging the low percentage of enrolled women and the lack of sex‐specific data, further research including patient‐level data is urgently needed to draw more definitive conclusions. [ABSTRACT FROM AUTHOR]

Background: The cardiac electrical biomarker (CEB) is a novel electrocardiographic (ECG) marker quantifying the dipolar activity of the heart with higher levels indicating myocardial injury.Methods: We prospectively enrolled 1097 patients presenting with suspected non-ST-elevation myocardial infarction (NSTEMI) to the emergency department (ED). Digital 12-lead ECGs were recorded at presentation and the CEB values were calculated in a blinded fashion. The final diagnosis was adjudicated by two independent cardiologists. The prognostic endpoint was all-cause mortality during 2 years of follow-up.Results: NSTEMI was the final diagnosis in 14% of patients. CEB levels were higher in patients with NSTEMI compared to other causes of chest pain (median 44 (IQR 21-98) vs. 30 (IQR 16-61), p < .001). A weak but significant correlation between levels of high-sensitivity cardiac troponin T (hs-cTnT) at admission to the ED and the CEB was found (r = .23, p < .001). The use of the CEB in addition to conventional ECG criteria improved the diagnostic accuracy for the diagnosis of NSTEMI as quantified by the area under the receiver operating characteristics curve from 0.66 to 0.71 (p < .001) and the sensitivity improved from 43% to 79% (p < .001).Conclusion: In conclusion, the CEB, an ECG marker of myocardial injury, significantly improves the accuracy and sensitivity of the ECG for the diagnosis of NSTEMI. [ABSTRACT FROM AUTHOR]

Background: The phenomenon of exercise‐induced left ventricular dysfunction (LVD) is incompletely understood. Better understanding of its prevalence and determinants might help to address the current potential oversimplification of the relation between physical activity and cardiac health in patients with coronary artery disease (CAD). Methods: We prospectively assessed the prevalence and determinants of exercise‐induced LVD in patients with stable CAD and normal LV function at rest undergoing bicycle rest/stress myocardial perfusion imaging single‐photon emission computed tomography (MPI‐SPECT). Exercise‐induced LVD was defined as a relevant (5% or more) drop in left ventricular ejection fraction after maximal exercise. High‐sensitivity cardiac troponin I/T (Hs‐cTnI/T) and N‐terminal probrain natriuretic peptide (NT‐proBNP) concentrations were measured before exercise to quantify cardiomyocyte injury and hemodynamic cardiac stress, respectively. Results: Among 317 patients, exercise‐induced LVD was present in 83 (26%) patients. Exercise‐induced LVD was associated with the extent of exercise‐inducible myocardial ischaemia as well as transient ischaemic dilatation. Still, 43% of patients developing exercise‐induced LVD did not have functionally relevant CAD. Neither baseline characteristics, nor the quantification of the extent of cardiomyocyte injury and hemodynamic cardiac stress using hs‐cTnI/T and NT‐proBNP concentrations, respectively, allowed predicting exercise‐induced LVD. Conclusion: One out of four patients with stable CAD develops exercise‐induced LVD after bicycle exercise test. While the extent of exercise‐inducible myocardial ischaemia is a predictor, other still unrecognized mechanisms also seem to play a major role, as nearly half of all patients with exercise‐induced LVD do not have functionally relevant CAD. [ABSTRACT FROM AUTHOR]

Background Venous thromboembolism (VTE) contributes significantly to COVID-19 morbidity and mortality. The urokinase receptor system is involved in the regulation of coagulation. Levels of soluble urokinase plasminogen activator receptor (suPAR) reflect hyperinflammation and are strongly predictive of outcomes in COVID-19. Whether suPAR levels identify patients with COVID-19 at risk for VTE is unclear. Methods and Results We leveraged a multinational observational study of patients hospitalized for COVID-19 with suPAR and D-dimer levels measured on admission. In 1960 patients (mean age, 58 years; 57% men; 20% Black race), we assessed the association between suPAR and incident VTE (defined as pulmonary embolism or deep vein thrombosis) using logistic regression and Fine-Gray modeling, accounting for the competing risk of death. VTE occurred in 163 (8%) patients and was associated with higher suPAR and D-dimer levels. There was a positive association between suPAR and D-dimer (β=7.34; P =0.002). Adjusted for clinical covariables, including D-dimer, the odds of VTE were 168% higher comparing the third with first suPAR tertiles (adjusted odds ratio, 2.68 [95% CI, 1.51-4.75]; P <0.001). Findings were consistent when stratified by D-dimer levels and in survival analysis accounting for death as a competing risk. On the basis of predicted probabilities from random forest, a decision tree found the combined D-dimer <1 mg/L and suPAR <11 ng/mL cutoffs, identifying 41% of patients with only 3.6% VTE probability. Conclusions Higher suPAR was associated with incident VTE independently of D-dimer in patients hospitalized for COVID-19. Combining suPAR and D-dimer identified patients at low VTE risk. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT04818866.