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Background: Tachycardia‐induced cardiomyopathy (TIC) is a reversible cardiomyopathy with ventricular dysfunction caused by tachyarrhythmias. Notably, atrial fibrillation (AF) is the most common causal arrhythmia leading to TIC. However, the risk factors for the development of TIC due to AF remain unclear. This study aimed to identify the associated factors of TIC due to AF. Methods: Persistent AF patients with heart rate (HR) ≥100 beats per minute who underwent initial catheter ablation were enrolled in this study. TIC was diagnosed as left ventricular ejection fraction (LVEF) < 50% during AF rhythm, which was recovered after the restoration of sinus rhythm. Non‐TIC was defined as LVEF ≥ 50% despite AF rhythm. The patient backgrounds were compared between the TIC group and the non‐TIC group to reveal the contributing factors of TIC. Results: The TIC group comprised 57 patients, while the non‐TIC group consisted of 101 patients. The TIC group was younger than the non‐TIC group (median 64 vs. 70, p = 0.006). Male sex was more frequent in the TIC group than the non‐TIC group (82.5% vs. 58.4%, p = 0.003). HR was higher in the TIC group than in the non‐TIC group (median 130 bpm vs. 111 bpm, p < 0.001). The number of smokers was significantly higher in the TIC group than in the non‐TIC group (p < 0.001). Multivariable analysis demonstrated that higher HR (odds ratio [OR]: 1.74; 95% confidence interval [CI]: 1.37–2.21; p < 0.001) and current smokers (OR: 5.27; 95% CI: 1.60–17.4; p = 0.006) were the independent factors leading to TIC. Conclusion: Higher HR and current smokers were independent risk factors for the development of TIC due to AF. [ABSTRACT FROM AUTHOR]

We report a 5‐year‐old girl with transient complete atrioventricular (AV) block following surgical closure of a symptomatic conoventricular ventricular septal defect (VSD) which recovered on post‐operative day 9. She later presented with exertional dizziness and fatigue. While congenital cardiac defect repairs are occasionally complicated by complete heart block, this patient was found to have intra‐Hisian Wenckebach which is rare in the pediatric population and can be very difficult to discern from surface electrocardiograms and by Holter monitoring. Mechanisms of post‐surgical AV block, including intra‐Hisian Wenckebach, are not well characterized in the pediatric population. [ABSTRACT FROM AUTHOR]

Background: Atrial fibrillation (AF) is the most common sustained atrial arrhythmia. Accurate detection of the timing and possibility of AF termination is vital for optimizing rhythm and rate control strategies. The present study evaluated whether the ventricular response (VR) in AF offers a distinctive electrocardiographic indicator for predicting AF termination. Methods: Patients experiencing sustained paroxysmal AF for more than 3 h were observed using 24‐h ambulatory Holter monitoring. VR within 5 min before AF termination (VR 0–5 min, BAFT) was compared with VR observed during the 60th to 65th min (VR 60–65 min, BAFT) and the 120th to 125th min (VR 120–125 min, BAFT) before AF termination. Maximum and minimum VRs were calculated on the basis of the average of the highest and lowest VRs across 10 consecutive heartbeats. Results: Data from 37 episodes of paroxysmal AF revealed that the minimum VR0–5 min, BAFT (64 ± 20 bpm) was significantly faster than both the minimum VR120–125 min, BAFT (56 ± 15 bpm) and the minimum VR60–65 min, BAFT (57 ± 16 bpm, p <.05). Similarly, the maximum VR0–5 min, BAFT (158 ± 49 bpm) was significantly faster than the maximum VR120–125 min, BAFT (148 ± 45 bpm, p <.05). In the daytime, the minimum VR0–5 min, BAFT (66 ± 20 bpm) was significantly faster than both the minimum VR60–65 min, BAFT (58 ± 17 bpm) and minimum VR120–125 min, BAFT (57 ± 15 bpm, p <.05). However, the mean and maximum VR0–5 min, BAFT in the daytime were similar to the mean and maximum VR120–125 min in the daytime, respectively. At night, the minimum, mean, and maximum VR0–5 min, BAFT were similar to the minimum, mean, and maximum VR120–125 min, respectively. Conclusions: Elevated VR rates during AF episodes may be predictors for the termination of AF, especially during the daytime and in patients with nondilated left atria. These findings may guide the development of clinical approaches to rhythm control in AF. [ABSTRACT FROM AUTHOR]

Background: There are important physiological changes in the heart rate autonomic modulation in pregnant women and these changes may affect the way their bodies respond to exercise stimulus. The objective of this review is to verify the physical exercise influence on autonomic modulation of heart rate in pregnant women. Methods: This study is a Systematic Review. The electronic databases used to search for the studies were Cochrane Library, MEDLINE via PUBMED, Regional Health Portal and EMBASE. Experimental studies that evaluated heart‐rate variability in pregnant women practicing physical exercises were included. And articles that addressed only fetal heart‐rate variability, case reports, congress abstracts, clinical trial protocols without results, preprints, and gray literature were excluded. There were no language or publication year restrictions. The descriptors used in the Search were Cardiac Chronotropism, Sympathetic Nervous System, Pregnancy, and Physical Exercise. For statistical analysis, the fixed effect model was used. Results: A total of 3106 articles were found, and 12 studies were included, which 5 were nonrandomized clinical trials, 4 were randomized clinical trials, and 3 were cross‐sectional studies. Three hundred and four pregnant women were included in the studies. The application of physical exercise was varied, but in general they used aerobic exercises and with increased variability of the heart rate and reflex on the autonomic modulation of heart rate. Conclusion: Most studies demonstrate benefits heart rate in pregnant women, but limited research makes it hard to compare specific types of exercise and larger studies are needed to identify the best exercise. [ABSTRACT FROM AUTHOR]

The pacing threshold is important for leadless pacemakers, as the pacing output has a significant impact on battery longevity. Acute pacing rate‐dependent threshold increases have also been reported with leadless pacemakers. In the present case, we experienced a case in which the threshold, which had been raised in the acute phase, once showed a tendency to improve, but then worsened again. And, as in previous reports, thresholds improved completely in the chronic phase. Repeated retrieval and reimplantation of leadless pacemakers increases the likelihood of fatal complications, so being aware of such phenomenon may prevent unnecessary procedure and complications. [ABSTRACT FROM AUTHOR]

Purpose: The available data on the treatment strategy of pulsed field ablation (PFA) for patients with atrial fibrillation (AF) is limited. This study aims to provide a comparative analysis of the efficacy, safety, and procedural efficiency between PFA and cryoballoon ablation (CBA) for AF. Methods: We conducted a comprehensive search of the EMBASE, PubMed, Cochrane Library, and ClinicalTrials.gov databases to identify trials comparing PFA with CBA for AF from their inception until December 2023. The odds ratio (OR) and mean difference (MD), along with a 95% confidence interval (CI), were utilized as measures of treatment effect. Results: The analysis included 15 eligible trials with a total enrollment of 1880 patients. No significant differences were found in recurrent atrial arrhythmia (OR 0.83, 95% CI 0.64, 1.07) or periprocedural complications (OR 0.78, 95% CI 0.46, 1.30) between the two ablation techniques examined in this study. However, the PFA technique demonstrated a significantly shorter procedure time (MD ‐7.17, 95% CI ‐13.60, ‐0.73), but a longer fluoroscopy time (MD 2.53, 95% CI 0.87, 4.19). Similarly, PFA was found to be significantly associated with a decreased incidence of phrenic nerve palsy (OR 0.20, 95% CI 0.07, 0.59), but an increased incidence of cardiac tamponade (OR 4.07, 95% CI 1.15, 14.39). Moreover, there was a significantly higher release of troponin with PFA compared to CBA (MD 470.28, 95% CI 18.89, 921.67), while the increase in S100 protein and heart rate was significantly lower with PFA than with CBA (MD ‐64.41, 95% CI ‐105.46, ‐17.36), (MD ‐8.76, 95% CI ‐15.12, ‐2.40). Conclusion: The utilization of PFA provides a safer, time‐saving, and tissue‐specific procedure compared to CBA, while maintaining comparable success rates. This has the potential to enhance procedural efficiency and optimize resource utilization in clinical practice. These findings underscore the feasibility and promise of PFA as an alternative technique for PVI in patients with AF. [ABSTRACT FROM AUTHOR]

Background: Heart rate score (HRS) ≥ 70% has been associated with arrhythmic events and mortality but these studies were not specific for heart failure (HF) patients. We hypothesized that HRS ≥ 70% obtained from remote monitoring (RM) is associated with HF hospitalizations and arrhythmic events in HF with reduced ejection fraction (HFrEF). Methods: HRS was calculated from RM in patients with HFrEF and ICD or CRT‐D. Two groups were defined: HRS ≥ 70% (G1, n = 55) and HRS < 70% (G2, n = 48) Results: A total of 103 patients were included (64.4 ± 13.04 years, 69.9% male, mean left ventricular ejection fraction (LVEF) 33.62 ± 11.97% and FUP 61.7 ± 38.87 months). The device was CRT‐D in 59.2% and ICD in 40.8% and the majority (90.3%) had the device implanted in primary prevention. G1 patients were more frequently male (p =.017) and had more coronary disease (p =.035). HRS ≥70% was an independent predictor for unplanned HF hospitalizations (OR: 1.905 (95% CI: 1.328–3.649), p <.001)). The indication for device implantation (primary vs. secondary prevention), type of device, NYHA class, age, gender and LVEF were not independent predictors of the outcome. VF (4.9 ± 20.0 G1 vs. 1.1 ± 5.47 G2, p =.046) and VT episodes were more prevalent in G1 (3.1 ± 8.93 G1 vs. 0.3 ± 1.59 G2, p =.026), as well as appropriate device shocks (4.3 ± 12.06 G1 vs. 0.3 ± 1.49 G2, p =.023). There was no difference in inappropriate shocks or mortality outcomes between groups. Conclusion: HRS ≥70% obtained from RM was an independent predictor of HF hospitalizations and was associated with arrhythmic events with VT and VF episodes and appropriate device shocks in HFrEF patients. [ABSTRACT FROM AUTHOR]

Background: Long QT syndrome (LQTS) is a sudden death predisposing condition characterized by ECG‐derived prolongation of the QT interval. Previous studies have demonstrated that the supine‐stand test may aid in the diagnosis of LQTS as patients fail to shorten their QT interval in response to standing up. The aim of this study was to evaluate the diagnostic accuracy of ECG data derived from standard protocol, clinically performed treadmill exercise stress tests (TESTs) in their ability to mimic the formal supine‐stand test. Methods: We performed a retrospective review of 478 TESTs from patients evaluated for LQTS. Patients referred for evaluation of LQTS but who were dismissed as normal served as controls. Heart rate & QT values were obtained from standard protocol TESTs. Results: Overall, 243 patients with LQTS (125 LQT1, 63 LQT2, 55 LQT3; 146 [60%] female, mean age at TEST 30 ± 17 years) and 235 controls (142 [60%] female, mean age 24 ± 15 years) were included. The paired ΔQTc (QTcStand‐QTcSupine) was similar between LQTS (−5 ± 26) and controls (−2 ± 25; p =.2). During position change, the QT interval shortened by ≥20 ms in 33% of LQTS patients, remained unchanged in 62%, and increased in 5% of LQTS patients which was similar to controls (shortened in 40%, unchanged in 54%, and increased in 6% of controls; p =.2). Receiver‐operator curve analysis to test the diagnostic ability of supine‐stand ΔQT performed poorly in differentiating LQTS from controls with an of AUC 0.52 (p =.4). Conclusion: TESTs should be used with caution when trying to interpret supine‐stand changes for diagnosis of LQTS. [ABSTRACT FROM AUTHOR]

Background: Sudden cardiac death (SCD) risk markers are needed in Chagas cardiomyopathy (CC). Action potential duration restitution (APDR) dynamics is capable of extracting information on cardiac regional heterogeneity. This study intends to develop a patient‐specific variables‐based algorithm to predict SCD in the low‐intermediate subgroups of the Rassi risk score. Methods: Cross‐sectional study of patients who underwent 24‐h Holter for research purposes between January 1992 and February 2017. From 4‐h ECG segment, RR series were generated and APDR dynamics metrics were calculated. Classification tree and sensitivity analysis were applied. As outcomes, SCD, SCD‐free and non‐cardiovascular death and 34 variables were included. Results: Two hundred twenty‐one (129 in the group SCD‐free, 80 in the SCD group and 12 non‐cardiovascular death group) were analyzed. In the groups with and without SCD (209 patients), the median age was 66 years, 52% were female, the cardiac involvement was mild to moderate in 72% with a Rassi point median of 8 (IQ: 3 to 11). The SCD group had more ventricular remodeling and more ventricular electrical instability. The occurrence of a %beats QTend/TendQ ratio > 1 (AUC, 0.96 (95% CI 0.89–0.98) present in more than 56.7% of the 4‐h ECG segments was sufficient to identify patients of the SCD subgroup. Variables representing different stages of CC were also relevant in the model. Conclusion: It is possible to use APDR dynamics as an adjuvant in the SCD risk assessment in a subgroup of patients with a high risk of SCD and a very low risk of non‐CV death with high power of discrimination. [ABSTRACT FROM AUTHOR]

Background: The anatomic extent of the reentry circuit in idiopathic left posterior fascicular ventricular tachycardia (LPF‐VT) is yet to be fully elucidated. We hypothesized that entrainment mapping could be used to delineate the reentry circuit of an LPF‐VT, especially including the upper turnaround point. Methods: Twenty‐three consecutive LPF‐VT patients (mean age, 29 ± 9 years, 18 males) were included. We performed overdrive pacing with entrainment attempts at the left bundle branch (LBB) and the left His bundle (HB) region. Results: Overdrive pacing from the LBB region showed concealed fusion in all 23 patients (post‐pacing interval [PPI], 322.1 ± 64.3 ms; tachycardia cycle length [TCL], 319.0 ± 61.6 ms; PPI‐TCL, 3.1 ± 4.6 ms) with a long stimulus‐to‐QRS interval (287.9 ± 58.0 ms, approximately 90% of the TCL). Pacing from the same LBB region at a slightly faster pacing rate showed manifest fusion with antidromic conduction to the LBB and minimal in‐and‐out time to the LBB potential (PPI‐TCL, 21.3 ± 13.7 ms). Overdrive pacing from the left HB region showed manifest fusion with a long PPI‐TCL (53.9 ± 22.5 ms). Conclusions: Our pacing study results suggest that the upper turnaround point in a reentry circuit of the LPF‐VT may extend to the proximal His‐Purkinje conduction system near the LBB region but below the left HB region. The LPF may constitute the retrograde limb of the reentry circuit. [ABSTRACT FROM AUTHOR]

Background and aim of the study: The response to the increase in heart rate (HR) could be characterized by failure in both left ventricular (LV) and left atrial (LA) functions. This study aimed to evaluate the relationship between the increase in paced HR and the changes in LV and LA functions, assessed by two‐dimensional speckle tracking analysis. Methods: In a group of patients with an implantable cardioverter defibrillator (ICD) or pacemaker, the atrial paced rhythm was progressively increased from 60 to 70, from 70 to 80, and from 80 to 90 beats per minute (bpm). For each paced HR, using two‐dimensional speckle tracking analysis, LA reservoir (LAr), LA conduit (LAc), LA contraction (LAct), and LV global longitudinal strain (LV‐GLS) were evaluated every 10 bpm. Results: Of the 45 patients enrolled, a significant reduction in LAr was observed at higher HR. However, when the patients were dichotomized according to the HR‐related response of LV‐GLS, the worsening of LAr was observed in those with LV‐GLS worsening and not in those without (maximum LAR absolute changes −2.7 ± 7.2% vs. +2.7 ± 7.2%, respectively, p.028). Moreover, the worsening of LA and LV strain measures was associated with an increase in the estimated filling pressures. Conclusions: In patients with atrial paced rhythm, the increase in HR could be associated with worsening of LA and LV functions, as assessed by two‐dimensional speckle tracking analyses. These results offer new data on HR‐related atrioventricular function and could be useful for guiding the optimal HR responsiveness of the implanted devices. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 94-year-old woman with a dual-chamber pacemaker experiencing dysfunction in the leads, revealing a rare complication known as "pseudotransposition" due to continuous friction between atrial and ventricular leads. Topics discussed include diagnostic challenges, stable impedance values despite lead abnormalities, and the significance of chest x-rays in confirming lead integrity.

Introduction: Implantable loop recorders (ILR) are used to screen for atrial fibrillation (AF) in patients with cryptogenic stroke (CS). However, there is limited real‐world data regarding the long‐term rate of AF detection using ILR and management consequences in patients with CS. The objective is to assess the rate of AF detection in patients with CS in a real‐world study over 36 months of follow‐up and its consequences on stroke prevention. Methods: This retrospective study included patients with an ILR placed for CS at Baylor College of Medicine and Baylor St. Luke's Medical Center between January 2014 and July 2021. The primary outcome was AF detection in patients with ILR. The secondary outcome was the rate of subsequent strokes after ILR placement in patients with or without diagnosed AF. The AF detection rate in our cohort was compared to the rate in CRYSTAL‐AF Trial at 36‐month follow‐up. The impact of AF detection on clinical management was examined. Results: We identified 225 patients. 51.1% were women and 38.2% African American. Among 85 patients with ILR labeled AF, 43 patients had true AF, and 42 had incorrectly labeled AF (48.3% false positive). The estimated AF detection rate at 36 months follow‐up was 28.6% (95% CI, 26.6%–30.6%). 58.1% of patients with AF were initiated on oral anticoagulation, 80.0% of whom were started on a direct oral anticoagulant. 13.8% of patients had recurrent strokes after ILR implantation; 4 of whom were diagnosed with AF. Conclusion: Compared to CRYSTAL‐AF, the AF detection rate in our cohort is similar, but this cohort includes a higher proportion of female and African American patients. Most patients with recurrent strokes after ILR implant did not have AF during 36 months of monitoring. [ABSTRACT FROM AUTHOR]

Background: The safety and efficacy of leadless pacemakers (LP) in transcatheter aortic valve implant (TAVI) patients is not well known due to paucity of data. Herein, we compared outcomes between leadless pacemakers to traditional dual chamber pacemakers (DCP) following TAVI. Methods: A single‐center retrospective study was conducted, including a total of 27 patients with LP and 33 patients with DCP after TAVI between November 2013 and May 2021. We compared baseline demographics, pacemaker indications, complication rates, percent pacing, and ejection fractions. Results: Leading indications for pacemaker implant were complete heart block (74% LP, 73% DCP) and high degree atrioventricular block (26% LP, 21% DCP). Twenty‐two (82%) LP patients had devices implanted in the right ventricular septal‐apex. Three (9%) DCP patients required rehospitalization for pocket related complications. Zero pacemaker‐related mortality was observed in both groups. Frequency of ventricular pacing and ejection fraction was similar between LP and DCP groups. Conclusion: From this single‐center retrospective study, LP implant was feasible following TAVI and was found to have comparable performance to DCPs. LPs may be a reasonable alternative in TAVI patients where single ventricular pacing is indicated. Larger studies are required to validate these findings. [ABSTRACT FROM AUTHOR]

The selection of patients with chronotropic incompetence (CI) for cardiac pacing therapy remains challenging. Here, we present a case of a 40‐year‐old woman with severe exertional dyspnea. The exercise test revealed a blunted increase in the heart rate (HR) (maximum of 110 bpm). Her exercise capacity significantly improved under atrial stimulation at 170 bpm using a temporary pacing lead. Therefore, we implanted a rate‐adaptive dual‐chamber pacemaker with a blended sensor. During follow‐up exercise capacity normalized, and she had no residual exertional dyspnea at 6 months. This case highlights the potential value for individual assessments of CI to identify clear indications for pacemaker implantation. [ABSTRACT FROM AUTHOR]

The article present a case study of 76-year-old man presented to the cardiopulmonary stress testing laboratory for the evaluation of progressive dyspnea on exertion. It further discusses that cardiopulmonary stress testing, leading to dyspnea on exertion; phenomenon, known as pacemaker Wenckebach, occurs when the patient's sinus rate approaches the maximal tracking rate of the pacemaker, resulting in dropped ventricular contractions.

Background: We recently described a novel pacemaker‐mediated arrhythmia in Abbott cardiac implantable electronic devices (CIED), called pseudo‐RNRVAS, that mimics repetitive non‐reentrant ventriculoatrial synchrony (RNRVAS), but can appear in patients with ventriculoatrial (VA) block. It is caused by sinus‐p‐waves, trapped in the post‐ventricular atrial refractory period (PVARP), which mimic VA conduction. The p‐waves are followed by atrial pacing during the myocardial refractory time, which can trigger atrial fibrillation (AF). Pseudo‐RNRVAS and RNRVAS are probably more common than appreciated, but the recognition and differentiation of the two can be challenging because most CIEDs do not recognize and store them. Objective: We illustrate practical challenges in the assessment of Pseudo‐RNRVAS and provide programming options that proved safe and effective for preventing Pseudo‐RNRVAS and reducing the risk for typical RNRVAS. Methods and Results: We illustrate in 10 patients the characteristics of Pseudo‐RNRVAS and their treatment. The outcome regarding the recurrence of pseudo‐RNRVAS after 6 months of follow‐up was collected. Inappropriate atrial pacing during pseudo‐RNRVAS resulted in AF in six patients. After shortening the PVARP in nine, inactivation/reduction of rate response in four, and reduction of the basic pacing rate in one patient, pseudo‐RNRVAS was avoided in eight patients and reduced in one. In one patient AF became permanent. Conclusions: Pseudo‐RNRVAS is a pacemaker‐mediated arrhythmia that can appear in patients without VA conduction and may lead to AF. The suggested adjustments of pacing parameters were safe and effective in preventing the arrhythmia. [ABSTRACT FROM AUTHOR]

Background: Hybrid ablation combines the advantages of surgical and catheter ablation. Many studies have explored the efficiency and safety of hybrid ablation in patients with nonparoxysmal AF. Methods: We systematically searched for prospective controlled trials that compared hybrid ablation with catheter/surgical ablation in PubMed, Web of Science, Wiley Library, and CNKI. Our main assessment indicators included maintenance of sinus rhythm (SR) without antiarrhythmic drugs for more than 12 months, major adverse events (MAEs), procedure time and fluoroscopy time. Results: Of 1214 identified studies, five were eligible and were included in our analysis (N = 451 participants). The pooled results showed that hybrid ablation was more effective in maintaining SR than a single procedure (surgical ablation or catheter ablation) (OR = 2.52, 95% confidence interval [CI]: 1.63–3.89, p <.001). Little significant heterogeneity was revealed (p =.32 for heterogeneity, I2 = 14%). More MAEs occurred in the hybrid group than in the single procedure group (OR = 7.47, 95% CI: 1.90–29.41, p =.004; I2 = 0%). Two trials reported the procedure and fluoroscopy times, and the procedure time for hybrid ablation was significantly longer than that of a single procedure (mean difference = 107.42, 95% CI: 88.62 to 126.22, p <.001; I2 = 82%). There was no significant difference in fluoroscopy time between the 2 groups (mean difference = –1.00, 95% CI: –5.37 to 3.36, p =.65; I2 = 12%). Conclusions: Hybrid ablation was more effective than catheter ablation and was as effective as surgical ablation in patients with nonparoxysmal AF. Meanwhile, hybrid ablation, especially concomitant hybrid ablation, increases the incidence of MAEs and prolongs the procedure time. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 62-year-old female with arterial hypertension suffering from markedly limited exercise tolerance and recurrent syncope associated with permanent sinus bradycardia. Topics include permanent atrial bigeminy with early single ectopic atrial P waves merging in the T waves and permanently not conducted to the ventricles; and demonstrated both central and peripheral bradycardia due to nonconducted atrial ectopics.

Background: Restricted outdoor activity during COVID‐19 related lockdown may accelerate heart failure (HF) progression and thereby increase cardiac arrhythmias. We analyzed the impact of March/April 2020 lockdown on physical activity and arrhythmia burden in HF patients treated with cardiac resynchronization therapy (CRT) devices with daily, automatic remote monitoring (RM) function. Methods: The study cohort included 405 HF patients enrolled in Observation of Clinical Routine Care for Heart Failure Patients Implanted with BIOTRONIK CRT Devices (BIO|STREAM.HF) registry in 16 countries, who had left ventricular ejection fraction (LVEF) ≤40% (mean 28.2 ± 6.6%) and NYHA class II/III/IV (47.9%/49.6%/2.5%) before CRT pacemaker/defibrillator implantation. The analyzed RM data comprised physical activity detected by accelerometer, mean heart rate and nocturnal rate, PP variability, percentage of biventricular pacing, atrial high rate episode (AHRE) burden, ventricular extrasystoles and tachyarrhythmias, defibrillator shocks, and number of implant interrogations (i.e., follow‐ups). Intraindividual differences in RM parameters before (4‐week period) versus during (4‐week period) lockdown were tested for statistical significance and independent predictors were identified. Results: There was a significant relative change in activity (mean −6.5%, p <.001), AHRE burden (+17%, p =.013), and follow‐up rate (−75%, p <.001) during lockdown, with no significant changes in other RM parameters. Activity decreased by ≥8 min/day in 46.5% of patients; predictors were higher LVEF, lower NYHA class, no defibrillator indication, and more activity before lockdown. AHRE burden increased by ≥17 min/day in 4.7% of patients; predictors were history of atrial fibrillation, higher LVEF, higher body mass index, and activity decrease during lockdown. Conclusion: Unfavorable changes in physical activity, AHRE burden, and follow‐up rate were observed during lockdown, but not in ventricular arrhythmia. [ABSTRACT FROM AUTHOR]

Introduction: Electrogram (EGM) fractionation is often associated with diseased atrial tissue; however, mechanisms for fractionation occurring above an established threshold of 0.5 mV have never been characterized. We sought to investigate during sinus rhythm (SR) the mechanisms underlying bipolar EGM fractionation with high‐density mapping in patients with atrial fibrillation (AF). Methods: Forty‐five patients undergoing AF ablation (73% paroxysmal, 27% persistent) were mapped at high density (18562 ± 2551 points) during SR (Rhythmia). Only bipolar EGMs with voltages above 0.5 mV were considered for analysis. When fractionation (> 40 ms and >4 deflections) was detected, we classified the mechanisms as slow conduction, wave‐front collision, or a pivot point. The relationship between EGM duration and amplitude, and tissue anisotropy and slow conduction, was then studied using a computational model. Results: Of the 45 left atria analyzed, 133 sites of EGM fragmentation were identified with voltages above 0.5 mV. The most frequent mechanism (64%) was slow conduction (velocity 0.45 m/s ± 0.2) with mean EGM voltage of 1.1 ± 0.5 mV and duration of 54.9 ± 9.4 ms. Wavefront collision was the second most frequent (19%), characterized by higher voltage (1.6 ± 0.9 mV) and shorter duration (51.3 ± 11.3 ms). Pivot points (9%) were associated with the highest degree of fractionation with 70.7 ± 6.6 ms and 1.8 ± 1 mV. In 10 sites (8%) fractionation was unexplained. The EGM duration was significantly different among the 3 mechanisms (p =.0351). Conclusion: In patients with a history of AF, EGM fractionation can occur at amplitudes > 0.5 mV when in SR in areas often considered not to be diseased tissue. The main mechanism of EGM fractionation is slow conduction, followed by wavefront collision and pivot sites. [ABSTRACT FROM AUTHOR]

A three‐axis accelerometer sensor is incorporated in a leadless pacemaker (MicraTM, MedtronicInc) for rate adaptation. Three sensor setpoints at lower rate (LR), activity of daily living rate (ADLR), and upper rate (UR) are used to convert detected acceleration to a desired rate response. We describe inappropriate rate acceleration at rest and during chest physiotherapy in a sedentary elderly patient with leadless pacemaker. The underlying mechanism and various programming options are discussed. [ABSTRACT FROM AUTHOR]

Background: Pulmonary vein (PV) isolation is an established treatment for paroxysmal drug‐refractory atrial fibrillation (AF). High parasympathetic tone and reconnection of PVs have demonstrated to be possible culprits of AF recurrence after ablation. Our aim was to investigate the association between parasympathetic tone and reconnected PVs in patients with paroxysmal AF. Methods: Consecutive patients who underwent a redo catheter ablation procedure for atrial tachyarrhythmia recurrence by means of 3D electroanatomic mapping with documentation of presence or absence of PVs reconnection following an initial procedure of cryoballoon (CB) ablation for symptomatic drug‐refractory paroxysmal AF were screened for the study. Results: A total of 92 patients were included, of whom 50 (54.35%) were males. Reconnected PVs were found in 64 (69%) patients. PVs reconnection could be predicted by DC (C‐statistic =.770), by SDNNI (C‐statistic =.714) and by absolute VLF power (C‐statistic =.722), while right‐sided PVs reconnection could be better predicted by DC (C‐statistic =.848) and by SDNNI (C‐statistic =.761). In multivariate binary logistic regression analysis, a DC value ≥6.45 ms and an absolute VLF power value ≥160 ms2 were associated with three times and five times higher odds of PVs reconnection, respectively. On a vein‐per‐vein analysis, absolute VLF power ≥160 ms2 was associated with three times higher odds, while reaching of −40°C within 60 s was associated with three times lower odds of PVs reconnection. Conclusion: High parasympathetic tonus accurately predicts PVs reconnection. On a vein‐per‐vein analysis, parasympathetic markers along with biophysical parameters predicted PVs reconnection. On a case‐by‐case analysis, parasympathetic markers were the only predictors of PVs reconnection, thus being a robust PVs reconnection prediction tool. [ABSTRACT FROM AUTHOR]

Background: An early, comprehensive rhythm‐control therapy is needed in order to treat atrial fibrillation (AF) effectively and to improve ablation outcomes. Methods: A total of 153 consecutive patients from the CHARISMA registry undergoing AF ablation at eight centers were included. Patients with de novo PVI were classified as having undergone early treatment (ET) if the procedure was performed within 6 months after the first AF episode, and as having undergone delayed treatment (DT) if ablation was performed over 6 months after the first AF episode. Results: One‐hundred fifty‐three patients were enrolled (69.9% male, 59 ± 10 years, 61.4% paroxysmal AF, 38.6% persistent AF). The time from the first AF episode to the ablation procedure was 1034 ± 1483 days. The ET group comprised 36 patients (25.3%), the DT group 60 (39.2%) and Redo cases were 57 (37.3%). During a mean follow‐up of 366 ± 130 days, 18 patients (11.8%) suffered an AF/AT recurrence. More DT patients than ET patients suffered recurrences (15.7% vs. 2.2%, p = 0.0452) and the time to AT/AF recurrence was shorter in the group of patients who received an ablation treatment after 6 months (HR = 6.19, 95% CI: 1.7 to 21.9; p = 0.0474). On multivariate Cox analysis, only hypertension (HR = 4.86, 95% CI: 1.6 to 14.98, p = 0.0062) was independently associated with recurrences. Beyond the hypertension risk factor, ET was associated with a low risk of recurrence; recurrence rate ranged from 0% (ET patients without hypertension) to 25.0% (DT patients with hypertension). Conclusions: An early rhythm‐control ablation therapy in the absence of common risk factors was associated with the lowest rate of recurrences. [ABSTRACT FROM AUTHOR]

Background: Ventricular scars due to myocardial infarction provide a substrate for ventricular arrhythmias, and cardiac magnetic resonance (CMR) is the golden standard for the quantification of scar tissue magnitude. CMR has still limitations with patients with ICD despite ICD's becoming MR‐compatible. We investigated the association between calibrated integrated backscatter (cIBS) and arrhythmia frequency in patients with ICD. Methods: Thirty‐two ischemic dilated cardiomyopathy (ICM) patients with VVI‐ICD (mean age 66.56 ± 9.05, 28 male, and four female) were divided into three groups according to their arrhythmia frequency (ventricular arrhythmia—[VA ‐], VA + [VA +], and arrhythmia storm [AS]). Then with transthoracic echocardiography (TTE), all patients' cIBS values were calculated and these values were compared with the patients' arrhythmia frequency. Results: cIBS values of patients with VA + and AS were significantly higher in the apical‐septal (0.66 ± 0.11 vs. 0.50 ± 0.16, p =.008) and apical‐lateral (0.62 ± 0.19 vs. 0.46 ± 0.18, p =.041) segments compared to those of patients with VA ‐. The cIBS values of apical‐septal (0.50 ± 0.16 vs. 0.65 ± 0.08 vs. 0.66 ± 0.13 respectively, p =.032) and apical‐anterior (0.53 ± 0.22 vs. 0.48 ± 0.17 vs. 0.79 ± 0.23 respectively, p =.03) segments were significantly different between the groups. Furthermore, in the post hoc analysis, the difference was significantly higher in VA + than VA ‐ in the apical‐septal segment and higher in AS than VA + in apical‐anterior segments. Conclusion: Our findings suggest an association between the cIBS values and arrhythmia frequency in the study group. [ABSTRACT FROM AUTHOR]

Background: Pulmonary vein isolation (PVI) with autonomic modulation may be more successful than PVI alone for atrial fibrillation (AF) ablation and may be signaled by changes in sinus rhythm heart rate (HR) post ablation. We sought to determine if a change in sinus rhythm HR predicted AF recurrence post PVI. Methods: Patients who underwent AF ablation from 2000 to 2011 were included if sinus rhythm was noted on ECG within 90 days pre and 7 days post ablation. Basic ECG interval and HR changes were analyzed and outcomes determined. Results: A total of 1152 patients were identified (74.3% male, mean age 57 ± 11 years). Mean AF duration was 5.2 ± 5.3 years. Paroxysmal AF was noted in 712 (61.8%) of the patients. Mean EF was 61% ± 6%. Sinus rhythm HR was 61 ± 11 pre‐ablation and 76 ± 13 bpm post‐ablation (27% ± 24% increase, p <.001). The ability of relative HR change post‐ablation to predict AF recurrence was borderline (hazard ratio 0.65 [0.41–1.01], p =.067). With patients separated into quartiles based on the relative HR change, the upper quartile with the largest relative increase in HR had a significantly lower rate of AF recurrence compared to the lowest quartile following multi variable modeling (p =.038). There were significant changes in PR (171 ± 28 to 167 ± 30 ms) and QTc (424 ± 25 to 434 ± 29 ms) intervals (both p <.001) but these were not predictive of outcome. Conclusion: Relative changes in HR post AF ablation correlates with AF recurrence. Further prospective studies are needed to confirm this relationship. [ABSTRACT FROM AUTHOR]

The article presents the case of a 33-year-old woman who was presented to a hospital due to recurrent ventricular tachycardia/ventricular fibrillation (VT/VF) episodes and multiple defibrillations to discuss the use of cardiac biopsy in patients with cardiomyopathy of unknown etiology undergoing electrical storm ablation. Topics include sarcoidosis, congestive heart failure, and cardiac sarcoidosis (CS).

Background: Previous studies reported that hypo‐ and hyperthermia are associated with several atrial and ventricular electrocardiographical parameters, including corrected QT (QTc) interval. Enhanced characterization of variations in QTc interval and normothermic body temperature aids in better understanding the underlying mechanism behind drug induced QTc interval effects. The analysis' objective was to investigate associations between body temperature and electrocardiographical parameters in normothermic healthy volunteers. Methods: Data from 3023 volunteers collected at our center were retrospectively analyzed. Subjects were considered healthy after review of collected data by a physician, including a normal tympanic body temperature (35.5‐37.5°C) and in sinus rhythm. A linear multivariate model with body temperature as a continuous was performed. Another multivariate analysis was performed with only the QT subintervals as independent variables and body temperature as dependent variable. Results: Mean age was 33.8 ± 17.5 years and mean body temperature was 36.6 ± 0.4°C. Body temperature was independently associated with age (standardized coefficient [SC] = −0.255, P <.001), female gender (SC = +0.209, P <.001), heart rate (SC = +0.231, P <.001), P‐wave axis (SC = −0.051, P <.001), J‐point elevation in lead V4 (SC = −0.121, P <.001), and QTcF duration (SC = −0.061, P =.002). In contrast, other atrial and atrioventricular (AV) nodal parameters were not independently associated with body temperature. QT subinterval analysis revealed that only QRS duration (SC = −0.121, P <.001) was independently associated with body temperature. Conclusion: Body temperature in normothermic healthy volunteers was associated with heart rate, P‐wave axis, J‐point amplitude in lead V4, and ventricular conductivity, the latter primarily through prolongation of the QRS duration. [ABSTRACT FROM AUTHOR]

Background: It was reported that intravenous amiodarone might induce ventricular fibrillation for acute treatment in patients with atrial fibrillation (AF) and Wolff‐Parkinson‐White (WPW) syndrome. No study was done to assess its application comprehensively in this population. Methods: This study was a retrospective analysis and undertaken by reviewing medical records and electronic databases to search for patients admitted with tachycardia resulting from WPW syndrome and AF, who have intravenously administrated amiodarone at the emergency department from January 2008 to June 2018. Results: Thirty patients were involved in this study, of which 27 were males. The mean age of the patients was 47.8 ± 17.0 years. The mean systolic blood pressure and diastolic blood pressure were 111.9 ± 18.3 mmHg and 76.1 ± 14.6 mmHg, respectively. The mean heart rate was 171 (150‐189) beats per minute. Half of the patients (53.3%) had no comorbidities, and only one had prior syncope. Nearly 17 patients (56.7%) started with a loading dose of 150 mg. No ventricular acceleration or VF developed. The incidence of hypotension was 3.3% (1/30). Eighteen patients (60.0%) restored to sinus rhythm by amiodarone with the conversion time of 486.0 (229.0‐1278.0) minutes. Conclusions: Intravenous amiodarone might be an alternative for acute treatment of AF and WPW syndrome in patients characterized by stable hemodynamics, relatively low admission heart rate, few comorbidities, elder age, and no prior syncope. The loading dosage of 150 mg appeared to be preferred, and the maintenance period was better to less than 12 hours. Monitoring and electrolyte correction were also necessary. It is essential to keep a defibrillator nearby during pharmacologic cardioversion. [ABSTRACT FROM AUTHOR]

Introduction: The third‐generation subcutaneous implantable cardioverter‐defibrillator (S‐ICD) (EMBLEM™ A219, Boston Scientific) contains a new diagnostic tool to detect atrial fibrillation (AF) in S‐ICD patients, without the use of an intracardiac lead. This is the first study to evaluate the performance of the S‐ICD AF monitor (AFM). Methods: The AFM algorithm analyzes a subcutaneous signal for the presence of AF, similar to the signals collected by implantable and wearable diagnostic devices. The AFM algorithm combines heart rate (HR) scatter analysis with an HR histogram. The algorithm was tested against publicly available electrocardiogram databases (simulated performance). Real‐world performance of the algorithm was evaluated by using the S‐ICD LATITUDE remote monitoring (RM) database. Results: The simulated performance of the AFM algorithm resulted in a sensitivity of 95.0%, specificity of 100.0%, and positive predictive value (PPV) of 100.0%. To evaluate the real‐world performance of the AFM, 7744 S‐ICD devices were followed for up to 30 months by RM, whereof 99.5% had the AFM enabled. A total of 387 AF episodes were randomly chosen for adjudication, resulting in a PPV of 67.7%. The main cause of misclassification was atrial and ventricular ectopy. Conclusion: The AFM exhibited a very high sensitivity and specificity in a simulated setting, designed to maximize PPV in order to minimize the clinical burden of reviewing falsely detected AF events. The real‐world performance of the AFM, enabled in 99.5% of S‐ICD patients, is a PPV of 67.7%. [ABSTRACT FROM AUTHOR]

Introduction: Atrial fibrosis is associated with atrial fibrillation (AF) recurrence after ablation. This study aims to determine the relationship between soluble ST2 (sST2), a profibrotic biomarker, and AF recurrence after radiofrequency catheter ablation (RFCA). Methods: AF patients referred for RFCA were consecutively included from October 2017 to May 2019. Baseline characteristics were collected, and sST2 levels were determined before ablation. Left atrial substrate mapping was performed after circumferential pulmonary vein isolation under sinus rhythm, and substrate was modified in low‐voltage zones. A second procedure was recommended under recurrence. Results: Two hundred fifty‐eight patients (146 males, average age 61.0 ± 8.8) were included. After a medium follow‐up of 13.5 months, 52 patients (20.2%) had recurrence and received a second procedure. Preoperative sST2 level in patients with recurrence was significantly higher than that in patients without (31.3 ng/mL vs 20.3 ng/mL, P <.001). In those undergoing second ablation, sST2 level in patients with new abnormalities during endocardial mapping was significantly higher than that in patients without (43.0 ng/mL vs 22.1 ng/mL, P <.001). An sST2 level over 26.9 ng/mL could predict AF recurrence with new abnormalities during endocardial mapping with a sensitivity of 100% and a specificity of 75.9%. Multiple logistic analysis showed that sST2 level was an independent predictor of AF recurrence with new abnormalities during endocardial mapping (P <.001). Conclusions: sST2 level was associated with new abnormalities during endocardial mapping and recurrence of AF after ablation. It might have significance in choosing treatment strategies for AF. [ABSTRACT FROM AUTHOR]

Background: Among heart failure patients with implantable cardioverter defibrillators (ICDs), monomorphic ventricular tachycardia (MMVT) failing antitachycardia pacing (ATP) and terminated by shock renders higher mortality as compared to MMVT terminated by ATP only. It is unknown if the higher mortality in ATP failure reflects decompensated heart failure. Objective: It was the purpose of the present study to determine if ICD heart failure diagnostics can predict the failure of ATP and the need to shock to terminate MMVT. Methods: This was a single‐center retrospective review of 103 consecutive patients with Medtronic ICDs who had MMVT and received ICD therapy. Heart failure diagnostics preceding each MMVT event were reviewed including atrial fibrillation burden, patient activity, night heart rate, heart rate variability, Optivol® fluid index, and MMVT heart rate. Results: A total of 452 MMVT events were analyzed, of which 23% required shock. Compared to MMVT that responded to ATP, MMVT that failed ATP and required shock had significantly faster heart rates and higher atrial fibrillation burden. Patient activity, night heart rate, heart rate variability, and OptiVol® fluid index were similar between ATP responsive MMVT events and those that failed ATP. In a multivariate analysis adjusting for baseline characteristics, higher atrial fibrillation burden and lower patient activity were associated with ATP failure and shock termination. Conclusion: Device diagnostics associated with decompensated heart failure identified MMVT events that failed ATP and necessitated shock. [ABSTRACT FROM AUTHOR]

Background: Since arrhythmia treatment in patients with autoimmune disease (AD) is challenging, we aimed to assess the common "real‐world" practice in the electrophysiology centers. Methods: Twenty‐four young electrophysiologists being part of European Heart Rhythm Association filled questionnaire regarding arrhythmia management in AD. Results: Rheumatoid arthritis was the most commonly reported AD accompanied by cardiac arrhythmias. The most frequent observed arrhythmias were atrial fibrillation and premature atrial/ventricular contractions. Most often electrocardiographic abnormalities observed were increased heart rate variability, QT interval prolongation, and P‐wave dispersion, whereas echocardiographic abnormalities included left atrial enlargement, pericardial infusion, and left ventricular dysfunction. The most useful tool for arrhythmia management was guidelines and evidence‐based medicine, while training courses and websites were at least useful. A close collaboration with other specialists in arrhythmia management was reported in 58.3% of respondents. Glucocorticoids and cytostatic were the most reported arrhythmia‐induced drugs, whereas amiodarone and beta‐blockers were most effective antiarrhythmic drugs. The main reason that discouraged respondents from cardiac implantable devices implantation and catheter ablation was high infection complications risk and recurrences during long‐term follow‐up, respectively. Conclusions: Scant data and guidelines enforce exchange of experience to improve the arrhythmia treatment in AD. [ABSTRACT FROM AUTHOR]

Background: Heart Rhythm Society guidelines outlining magnetic resonance imaging (MRI) in patients with cardiac implantable electronic devices (CIEDs) excluded children and epicardial or abandoned leads due to theoretical risks of harm. Research investigating these risks is lacking. The primary objective of our study is to determine the incidence of adverse events to patients or CIEDs from MRI imaging. The secondary objective is to describe CIED‐related artifact on MRI images. Methods: A single‐center retrospective review was performed on all patients with CIEDs who underwent 1.5 Tesla MRI between July 2007 and May 2019. We subdivided patients among four cohorts: (1) patients <18 years of age, (2) epicardial leads, (3) abandoned endocardial leads, and (4) abandoned epicardial leads. Descriptive statistics pre‐ and post‐MRI and at follow‐up within 1.5 years were conducted. Results: Fifty‐four MRIs were performed on 40 patients. Median age was 21.2 years (IQR 12.0‐25.0). Eighteen (33%) MRIs contained abandoned leads; 20 (37%) contained epicardial leads. Three patients, one with abandoned epicardial leads and two with abandoned endocardial leads, experienced mild discomfort at the CIED site. One adult with endocardial leads experienced a pause in the heart rate while programmed in a nonpacing mode. No clinically important changes to CIED parameters occurred. Nine MRIs (17%), especially those with functional cardiac imaging, were uninterpretable due to image artifact. Conclusion: In this study, pediatric and adult CHD patients with CIEDs, many with epicardial or abandoned leads, underwent MRIs without clinically significant complications. In some, CIED artifact reduced cardiac MRI image quality due to CIED position. [ABSTRACT FROM AUTHOR]

Background: Programmed long AV delays and intrinsic long first degree AV block may increase risk for competitive atrial pacing (CAP) in devices without CAP avoidance algorithms. Methods: Patients identified with CAP‐induced mode switch episodes were followed clinically from September 2013 to August 2019. Attempts to avoid CAP included shortening of postventricular atrial refractory period (PVARP) or postventricular atrial blanking period (PVAB), or change to AAI or DDI modes. After observing associations with sensor‐driven pacing, rate response was inactivated in a subset. Results: Among 23 patients identified with CAP (22 St Jude Medical [Abbott]; one Boston Scientific Corporation devices), atrial fibrillation (AF) was induced in 12 (52%), lasting 10 seconds to 28 hours and 32 minutes. In one patient with an ICD CAP‐induced AF with rapid ventricular rates that triggered a shock, inducing ventricular fibrillation, syncope, and another shock. Changing AV delays and shortening of PVARP failed to resolve CAP. After noting that all had CAP during sensor‐driven pacing, rate response was inactivated in seven, resolving further device‐induced AF in the three of seven that had prior CAP‐induced AF. In two patients with intact AV conduction, AAI(R) pacing resolved further documentation of CAP. Conclusions: CAP predominantly occurs during sensor‐driven atrial pacing that competes with intrinsic atrial events falling in PVARP. Inactivation of the activity sensor or change to atrial‐based pacing modes (AAI/R) appears to effectively prevent induction of device‐induced atrial proarrhythmia. Ultimately, a corrective algorithm is needed to avoid CAP‐induced proarrhythmia. [ABSTRACT FROM AUTHOR]

Background: T‐wave morphology parameters, such as total cosine R‐to‐T (TCRT), T‐wave loop dispersion (TWLD), T‐wave morphology dispersion (TMD), and T‐wave residuum (TWR), were suggested to be robust markers for adverse cardiovascular outcomes. Yet, the normal range of these parameters is unknown. This study aimed to evaluate the weighted normal values of T‐wave morphology parameters of healthy individuals and study the effect of potential modifiers. Methods: A systematic search of studies published in PubMed was conducted. Only those reporting on control groups of healthy individuals were included. Weighted means were calculated for TCRT, TWLD, TMD, and TWR. Linear regression analysis was conducted for age, percentage of males, heart rate, and QTc. Results: The weighted TCRT was 0.40 ± 0.05, significantly higher than the various cutoffs previously suggested to identify high risk. There was some overlap between the results of weighted normal TMD (19.42 ± 6.77°), TWLD (38.51 ± 0.31), and relative TWR (0.118 ± 0.056%) and reports on the same parameters from patients with cardiovascular disease. Women were also characterized by higher TWLD, TMD, and relative TWR. TCRT was negatively correlated with age and heart rate, and positively correlated with QTc duration, although all associations were weak (R2 < 0.9). Conclusions: T‐wave morphology parameters reported in the medical literature span a broad range of values in healthy individuals. Seemingly abnormal values of TWLD, TMD, and relative TWR were often reported in healthy adults. The variability between studies may stem from methodological issues. Therefore, standardizing the methodology for measuring T‐wave morphology is imperative. [ABSTRACT FROM AUTHOR]

Background: Paucity of a premature ventricular complex (PVC) during ablation procedures may occur and be associated with a lower success rate. Isoproterenol (ISP) injections are commonly used to induce PVC; however, the induced tachycardia sometimes prevents the appearance of PVC. Epinephrine (EPI) administration may be an alternative strategy to induce PVC due to its smaller effect on heart rate (HR). This study sought to examine the electrophysiological impact of EPI injection, with a stepwise induction protocol, for infrequent intraprocedural PVC. Methods: We studied 78 consecutive patients who underwent catheter ablation of idiopathic frequent PVC. If no PVC was observed at the beginning of the procedure, ISP (10 µg) was injected. If clinical PVC was not induced by ISP administration, EPI (10 µg) was injected. Results: Of 18 patients without PVC at baseline, ISP injection induced PVC in five patients. Of the remaining 13 patients, EPI injection successfully induced PVC in seven patients (53%). The maximum HR and increments of HR after EPI injection were significantly lower than those after ISP injection (99 ± 15 vs 137 ± 15 bpm, P =.001; 22 ± 10 vs 53 ± 12 bpm, P <.001, respectively). There were no complications related to the induction protocol. Conclusion: EPI injection following ISP injection is an effective and safe stepwise approach for the induction of infrequent PVC in the electrophysiology laboratory. It is hypothesized that α‐ and β‐adrenergic receptor stimulation by EPI injections, with reduced HR acceleration compared to that with ISP injections, may result in the successful induction of PVC. [ABSTRACT FROM AUTHOR]

Introduction: Atrial flutter (AFL) and atrial fibrillation (AF) are common in pediatric patients with congenital heart disease and structurally normal hearts as well. Chemical cardioversion is attractive for patients with AFL/AF for a short period of time because of the ability to avoid sedation. We review a single center's experience with Ibutilide in pediatric patients in an effort to report on its safety and efficacy. Methods: We performed a retrospective chart review of pediatric patients (0‐21 years) who underwent chemical cardioversion for AFL/AF with Ibutilide (January 2011‐February 2019). Patients on another antiarrhythmic medication or attempted chemical cardioversion with another drug were excluded. Results: There were 21 patients who met inclusion criteria. Thirteen of the 21 (62%) patients were successfully cardioverted with Ibutilide (10 out of 13 had AF and four out of 13 required a second dose). There were no significant differences in baseline characteristics between those who were successfully cardioverted compared to those who were not. Administration of magnesium prior to administration did not appear to have an effect on the success rate. There was a significant increase in rate corrected QT interval (QTc) post Ibutilide administration, which returned to baseline prior to discharge. One patient had symptomatic bradycardia needing intravenous fluids and another had torsades requiring electrical cardioversion during Ibutilide administration. Conclusions: The success rate of chemical cardioversion with Ibutilide was similar in our experience as compared to studies in the adult population and the other lone pediatric study. Although adverse events were uncommon, Ibutilide administration warrants close monitoring and fully defining its efficacy warrants further pediatric experience. [ABSTRACT FROM AUTHOR]

A 76‐year‐old woman with permanent atrial fibrillation and a mechanical aortic valve came to our attention. Echocardiography showed a 50‐55% ejection fraction (EF) with good prosthesis performance. For symptomatic bradyarrhythmia, she received a VVI pacemaker (Proponent MRI L2010 model; Boston Scientific.). During follow‐up, frequent symptomatic (presyncopal) episodes of nonsustained episodes of ventricular tachycardia (VT) were detected. Amiodarone proved unsuccessful; she was then offered an upgrade to an implantable cardioverter defibrillator (ICD) and a subcutaneous ICD (S‐ICD) was chosen by the patient. A few weeks later, two sustained VT were detected and effectively treated with 80‐J shock delivery. In both cases, device interrogation revealed a VT rate around 163 bpm (370 ms cycle length), below the lowest device detection cutoff. The report is a case‐based review. [ABSTRACT FROM AUTHOR]

Background: The perioperative anesthesia care during subcutaneous implantable cardioverter‐defibrillator (S‐ICD) implantation is still evolving. Objective: To assess the feasibility and safety of S‐ICD implantation with monitored anesthesia care (MAC) versus general anesthesia (GA) in a tertiary care center. Methods: This is a single‐center retrospective study of patients undergoing S‐ICD implantation between October 2012 and May 2019. Patients were categorized into MAC and GA group based on the mode of anesthesia. Procedural success without escalation to GA was the primary endpoint of the study, whereas intraprocedural hemodynamics, need of pharmacological support for hypotension and bradycardia, length of the procedure, stay in the post‐anesthesia care unit, and postoperative pain were assessed as secondary endpoints. Results: The study comprises 287 patients with MAC in 111 and GA in 176 patients. Compared to MAC, patients in GA group were younger and had a higher body mass index. All patients had successful S‐ICD implantation. Only one patient (0.9%) in the MAC group was converted to GA. Despite a similar baseline heart rate (HR) and mean arterial blood pressure (MAP) in both groups, patients with GA had significantly lower HR and MAP during the procedure and more frequently required pharmacological hemodynamic support. Length of the procedure, stay in the postanesthesia care unit, and postoperative pain was similar in both groups. Conclusion: This retrospective experience suggests that implantation of S‐ICD is feasible and safe with MAC. Use of GA is associated with more frequent administration of hemodynamic drugs during S‐ICD implantation. [ABSTRACT FROM AUTHOR]

Background: Near‐infrared spectroscopy (NIRS) is a noninvasive method to measure regional tissue oxygenation (rSO2). In patients with atrial fibrillation (AF), cardiac output and endothelial function are altered. Peripheral tissue oxygenation may therefore be reduced. This study aims to describe the peripheral tissue oxygenation of the feet before and after synchronized electrical cardioversion (CV) of patients with AF using NIRS. Methods: Patients with AF undergoing CV were included and screened for peripheral arterial disease (PAD), diabetes mellitus (DM), and peripheral neuropathy (PN). NIRS was performed before and after CV under continuous ECG and monitoring of peripheral oxygen saturation. NIRS was registered on the dorsoplantar and plantar area of both feet. Capillary blood gas analysis was performed and left ventricular ejection fraction (LVEF) was determined. Results: Twelve patients (five women, seven men, age 70.8 ± 10.8 years) participated. None had history of PAD. DM was present in three (25%) patients. Two patients (16.7%) had PN. CV was successful in 11 patients. Overall, rSO2 improved significantly in all patients after CV (P = .0003). Mean improvement was 7.17%. There were no significant changes in body temperature, ankle‐brachial index, sO2, pO2, pCO2, pH, or lactate after CV. Heart rate was significantly lower (P < .0001) and LVEF significantly higher (P = .0123) after CV. Conclusions: In patients with AF, peripheral tissue oxygen saturation improves significantly after successful CV. This suggests that patients with PAD may not only benefit from interventional or surgical improvement of arterial vascularization, but also from CV in case of AF. [ABSTRACT FROM AUTHOR]

Background: Currently available second‐generation cryoballoon (CB2) is accepted as an effective and safe tool for pulmonary vein isolation (PVI). Although much more data exist about 1‐year outcomes of CB2 ablation, data on long‐term outcomes are scarce. Objective: We aimed to assess the long‐term outcomes of PVI using CB2 in a large‐scale symptomatic atrial fibrillation (AF) population at our tertiary referral center. Methods: In this nonrandomized prospective observational study, a total of 486 patients with paroxysmal (71%) or persistent (29%) AF who underwent index PVI using CB2 at our hospital between January 2013 and June 2017 were enrolled. Atrial tachyarrhythmia (ATa)‐free survival was defined as the absence of AF, atrial flutter, or atrial tachycardia recurrence ≥30 s following a 3 months blanking period. Predictors of recurrence were evaluated by univariate and multivariate Cox proportional hazards regression models. Results: Acute procedural success rate was 99.8% (1898/1902 PVs). Mean procedural and fluoroscopy time were 64.9 ± 9.2 and 12.1 ± 2.6, respectively. At median 39 (interquartile range: 26‐56) months follow‐up, ATa‐free survival was 78.6% after a single procedure (280/345 [81.2%] for paroxysmal AF vs. 102/141 [72.3%] for persistent AF, P =.019) and 84.4% after a mean 1.48 ± 0.42 ablations. Cox regression analysis showed that left atrium diameter, duration of AF history, and early ATa recurrence were found as the independent predictors of late recurrence. Phrenic nerve palsy was observed in 17 (3.5%) patients. Conclusions: CB2‐based PVI is effective to maintain sinus rhythm in a significant proportion of paroxysmal and persistent AF patients with an acceptable complication rate at long‐term follow‐up. [ABSTRACT FROM AUTHOR]

In patients with atrial fibrillation (AF), cardiac resynchronization therapy (CRT) is challenging because the ventricular rate of conducted AF exceeds the biventricular pacing rate. In the current report, we present a patient who received a CRT device that was programmed to ventricular sense response (VSR) on with VVI 40 beats per minute to allow the AF to be paced as fusion beats. We found that the pacing configuration resulting in the narrowest QRS in this patient was VVI 40 with VSR biventricular fusion pacing during AF. VSR mode allows for CRT delivery without the need to artificially increase heart rate. [ABSTRACT FROM AUTHOR]

Background: Premature ventricular contractions (PVCs) induced by subtle cardiac dysfunction are missed by echocardiography. We evaluated acoustic cardiography for detection of early electromechanical dysfunction in patients with idiopathic PVCs and normal left ventricular ejection fraction (LVEF), and investigated the impact of radiofrequency ablation (RFA) in reversing this adverse effect. Methods: Eighty‐six patients with PVCs and 33 normal controls having normal LVEF were studied. Fifty PVC patients were in the ablation group and 36 in the nonablation group. %Electromechanical activation time (%EMAT), %left ventricular systolic time (%LVST), third (S3) and fourth heart sound (S4), and systolic dysfunction index (SDI) during sinus rhythm (SR) were measured by acoustic cardiography (Audicor, Inovise Medical, Inc., Beaverton, OR, USA) pre‐ and postablation. In 28 patients, acoustic parameters were compared during SR without PVCs, and SR with single PVC, ≥ 2 PVCs, or ventricular tachycardia over 10‐second Audicor recording in a single patient at different times. Twenty‐four‐hour acoustic cardiographic and acoustic cardiographic Holter recording were used to assess the impact of PVC burden on electromechanical function in 41 patients. Results: %EMAT, S3, S4, and SDI showed significant worsening in the PVC versus control group. %EMAT and SDI were worsened with increasing PVC number in a 10‐second strip. %EMAT showed significant linear increment with increasing PVC burden. There was a significant improvement in %EMAT, %LVST, S3, S4, and SDI postablation in patients with PVCs. Conclusion: Acoustic cardiography can detect PVC‐induced minor electromechanical dysfunction in patients with normal LVEF. RFA can reverse this adverse effect. [ABSTRACT FROM AUTHOR]

Background: Atrial ganglionated plexus (GP) ablation was proved to have therapeutic effects on vasovagal syncope. The study aimed to investigate whether selective ablation of only right anterior GP (ARGP) and right inferior GP (IRGP) was effective in a canine model of vasovagal syncope. Methods: Seventeen mongrel dogs were divided into control (N = 10) and ablation group (N = 7). Bilateral thoracotomy was performed at the fourth intercostal space and ARGP and IRGP were ablated in the ablation group. A bolus of veratridine (15 ug/kg) was injected into the left atrium to induce vasovagal reflex. Surface electrocardiogram and blood pressure (BP) were continuously monitored. Heart rate (HR) variability was calculated to represent cardiac autonomic tone. Results: Veratridine injection induced vasovagal reflex in all dogs. HR decreased from 149 ± 17 to 89 ± 33 beats/min (P < 0.001) in the control group, while in the ablation group HR decreased from 141 ± 35 to 125 ± 34 beats/min (P = 0.032). The postveratridine HR in the ablation group was significantly higher than that in the control group (P = 0.045). A significantly less intense HR decrease was observed in the ablation group compared with control (–17 ± 16 vs –61 ± 34 beats/min, P = 0.006). Significant BP decreases were induced in both the groups (all P < 0.01), while no evident differences in postveratridine BP and the extent of BP decreases were found between the groups. HR variability revealed significant decrease in cardiac vagal tone after ablation [high‐frequency power, 0.50 (0.17–1.05) vs 6.28 (0.68–8.99) ms2, P = 0.005]. Conclusions: Selective ablation of ARGP + IRGP weakened cardiac parasympathetic control and significantly attenuated the cardioinhibitory response in an animal model of vasovagal reflex. This ablation strategy might be effective for vasovagal syncope with evident cardioinhibitory response. [ABSTRACT FROM AUTHOR]

Background: There is insufficient information about the long‐term prognosis of sudden cardiac arrest (SCA) survivors. We therefore derived a clinical score (Sudden Cardiac Arrest—mortality score, SCA—MS) that predicts long‐term mortality in patients surviving to hospital discharge and validated it in an independent cohort of SCA survivors. Methods: A total of 1433 SCA survivors data were collected, who were discharged from the hospitals of the University of Pittsburgh Medical Center between 2002 and 2012. The overall cohort was randomly divided into two near equal cohorts used for the derivation and validation of the SCA—MS, respectively. Results: The derivation cohort included 768 patients and identified serum potassium level>4.2 mg/dL at admission, the presence of atrial fibrillation at any time during the index hospitalization, and the presence of asystole or pulseless electrical activity as the initial documented rhythm as independent predictors of long‐term mortality. Based on the multivariable modeling result, one point was assigned to each one of these variables to create the SCA—MS that ranged from 0 to 3. In the validation cohort, the SCA—MS was predictive of long‐term mortality (hazards ratio = 1.69, 95% confidence interval 1.50‐1.91, P < 0.001) per 1‐point increment in the SCA—MS. Conclusions: We describe a new clinical score that predicts long‐term survival after SCA based on serum potassium levels at the admission, presence of atrial fibrillation, and documented rhythm of SCA. [ABSTRACT FROM AUTHOR]

Introduction: The predictive value of left atrial volume (LAV) in atrial fibrillation (AF) is known, but the relationship of right atrial volume (RAV) and biatrial volume (BAV) with AF recurrence after pulmonary vein isolation (PVI) is not clear. Cardiac magnetic resonance (CMR) imaging allows us to more precisely quantify atrial volume. We investigated LAV, RAV, and BAV as predictors of AF recurrence following PVI in AF patients. Methods and Results: We assessed 100 AF patients (age = 59.8 ± 9.5 years, 74 males, 26 females) who underwent nonenhanced CMR before their first PVI. LAV and RAV were measured using CMR. All patients were in sinus rhythm during CMR. BAV was calculated as the sum of LAV and RAV. During the 8‐month follow‐up, AF recurrence occurred in 23 patients. LAV, RAV, and BAV were significantly greater in patients with AF recurrence than in those without (LAV, 103.7 ± 25.8 vs 81.8 ± 24.2 mL, P < 0.001; RAV, 109.4 ± 27.0 vs 82.2 ± 19.6 mL, P < 0.001; BAV, 213.1 ± 46.7 vs 164.1 ± 38.7 mL, P < 0.001). Multivariate logistic regression analysis revealed that increased LAV, RAV, and BAV were significantly correlated with AF recurrence. The area under the receiver operation characteristic curve for BAV showed the largest value compared to that of LAV or RAV alone. Conclusions: LAV, RAV, and BAV were independent predictors of AF recurrence after PVI. Quantifying BAV may additionally improve prognostic stratification compared with LAV or RAV. [ABSTRACT FROM AUTHOR]

Abstract: Background: Piceatannol, a grape‐derived polyphenol, has been linked to proarrhythmic properties by aggravating inhomogeneous conduction delay in the ischemia‐reperfusion (IR) zone to enhance arrhythmogenic alternans in heart failure (HF) rabbits. The underlying molecular mechanisms of piceatannol‐induced conduction disturbance were unclear in this model. Methods: HF was induced by 4 weeks’ rapid ventricular pacing. IR injury was induced in vivo using a protocol of left coronary artery ligation and release. Left ventricular cardiomyocytes were isolated enzymatically for whole‐cell patch‐clamp studies. Piceatannol (10 μM) was administrated to test its inhibitory effect on sodium current (INa). Immunoblots studies and immunoenzymological staining were conducted in tissues sampled from the IR and remote zones. Results: Peak INa density was less in failing cardiomyocytes than control cardiomyocytes. IR injury further reduces peak INa density in both groups. Piceatannol showed a greater INa inhibitory effect in HF than control cardiomyocytes. Western blots showed reduced NaV 1.5 protein expression in the HF group compared to the control group but no significant difference between remote and IR zones. Immunostaining showed that IR led to cytosolic redistribution of NaV 1.5, especially in failing hearts. Conclusions: Downregulation of NaV 1.5 protein expression and reduced peak INa density are found in the failing hearts. Piceatannol exerts a greater inhibitory effect on peak INa in the failing cardiomyocytes than in the controls. IR injury further decreases peak INa density, which is more prominent in the failing hearts than in the control hearts. [ABSTRACT FROM AUTHOR]

Aim: Young patients with operated complex congenital heart defects (CHD) often develop sinus node dysfunction (SND) requiring permanent pacing with rate-responsive function. Activity-driven sensors cannot account for nonmovement stress and cannot modulate heart rate physiologically. Closed Loop Stimulation (CLS, Biotronik, Berlin, Germany) is a physiological rate-responsive pacemaker based on the indirect measure of ventricular contractility. No data are available on the effects of such pacing strategy in young patients.Methods: We report a series of nine patients with CHD and SND who underwent single-chamber CLS-atrial pacing with endocardial or epicardial lead. During the first 30 days, the pacemaker was programmed in AAI pacing mode and then was switched to CLS-atrial pacing mode. An in-hospital control was scheduled 1–2 months later to evaluate the CLS response to neurovegetative stresses (i.e.,nonmovement stress [Stroop color test, handgrip] and exercise stress test) and Holter monitor. CLS pacing was compared with rate-responsive accelerometer-driven pacing (AAIR).Results: At telemetric interrogation, CLS pacing showed a more physiological pattern of 24-h heart rate trends than accelerometer sensors. The data obtained during nonmovement/exercisestress demonstrated a physiological increase in the pacing rate with CLS, in synergy with spontaneous events. The accelerometer sensor histogram, during nonmovement stress, showed a “non-response" behavior (only lower rate events), and during exercise test showed most events in lower rate range. Holter monitoring showed increase of average and maximum heart rate compared with AAIR.Conclusion: In young CHD patients, endocardial/epicardial CLS-atrial pacing demonstrated a physiological response of heart rate to neurovegetative and physical stresses. [ABSTRACT FROM AUTHOR]