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BackgroundCardiac resynchronization therapy (CRT) has been shown to improve both the functional status and mortality of heart failure patients with left bundle branch block. Multiple recent studies suggest several mechanisms for proarrhythmia associated with CRT device.Case summaryA 51-year-old male with symptomatic non-ischemic cardiomyopathy and no previous history of ventricular arrhythmias underwent placement of a biventricular cardioverter-defibrillator. The patient developed sustained monomorphic ventricular tachycardia (VT) soon after implantation. The VT recurred despite reprogramming to right ventricular only pacing. The electrical storm resolved only after a subsequent discharge from the defibrillator caused inadvertent dislodgement of the coronary sinus lead. No recurrent VT occurred throughout 10-years follow up after urgent coronary sinus lead revision.DiscussionWe describe the first reported case of mechanically induced electrical storm due to the physical presence of the CS lead in a patient with a new CRT-D device. It is important to recognize mechanical proarrhythmia as a potential mechanism of electrical storm, as it may be intractable to device reprogramming. Urgent coronary sinus lead revision should be considered. Further studies on this mechanism of proarrhythmia are needed.

PurposePrior studies reporting efficacy of radiofrequency catheter ablation for complex ventricular ectopy in mitral valve prolapse (MVP) are limited by selective inclusion of bileaflet MVP, papillary muscle only ablation, or short-term follow-up. We sought to evaluate the long-term incidence of hemodynamically significant ventricular tachycardia (VT) or fibrillation (VF) in patients with MVP after initial ablation.MethodsWe studied consecutive patients with MVP undergoing ablation for complex ventricular ectopy between 2013 and 2017 at our institution. Of 580 patients with MVP, we included 15 (2.6%, 10 women; mean age 50 ± 14 years, 53% bileaflet) with complex ventricular ectopy treated with initial ablation.ResultsOver a median follow-up of 3406 (1875-6551) days or 9 years, 5 of 15 (33%) patients developed hemodynamically significant VT/VF after their initial ablation and underwent placement of an implantable cardioverter defibrillator (ICD). Three of 5 also underwent repeat ablations. Sustained VT was inducible prior to index ablation in all 5 who developed VT/VF, compared to none of the 10 patients who did not develop VT/VF after index ablation (p = 0.002). Complex ventricular ectopy at index ablation was multifocal in all 5 patients who underwent repeat intervention versus 4 of 10 patients (40%) who did not (p = 0.04). All 3 patients with subsequent VT/VF who underwent repeat ablation had a new clinically dominant focus of ventricular arrhythmia and 3 of the patients with ICD had appropriate VT/VF therapies.ConclusionsIn the long term, a subset of MVP patients treated with ablation for ventricular arrhythmias, all with multifocal ectopy on initial EP study, develop hemodynamically significant VT/VF. Our findings suggest the progressive nature of ventricular arrhythmias in patients with MVP and multifocal ectopy.

ObjectivesThis study sought to identify acute changes in human atrial electrophysiology during alcohol exposure.BackgroundThe mechanism by which a discrete episode of atrial fibrillation (AF) occurs remains unknown. Alcohol appears to increase the risk for AF, providing an opportunity to study electrophysiologic effects that may render the heart prone to arrhythmia.MethodsIn this randomized, double-blinded, placebo-controlled trial, intravenous alcohol titrated to 0.08% blood alcohol concentration was compared with a volume and osmolarity-matched, masked, placebo in patients undergoing AF ablation procedures. Right, left, and pulmonary vein atrial effective refractory periods (AERPs) and conduction times were measured pre- and post-infusion. Isoproterenol infusions and burst atrial pacing were used to assess AF inducibility.ResultsOf 100 participants (50 in each group), placebo recipients were more likely to be diabetic (22% vs. 4%; p = 0.007) and to have undergone a prior AF ablation (36% vs. 22%; p = 0.005). Pulmonary vein AERPs decreased an average of 12 ms (95% confidence interval: 1 to 22 ms; p = 0.026) in the alcohol group, with no change in the placebo group (p = 0.98). Whereas no statistically significant differences in continuously assessed AERPs were observed, the proportion of AERP sites tested that decreased with alcohol (median: 0.5; interquartile range: 0.6 to 0.6) was larger than with placebo (median: 0.4; interquartile range: 0.2 to 0.6; p = 0.0043). No statistically significant differences in conduction times or in the proportion with inducible AF were observed.ConclusionsAcute exposure to alcohol reduces AERP, particularly in the pulmonary veins. These data demonstrate a direct mechanistic link between alcohol, a common lifestyle exposure, and immediate proarrhythmic effects in human atria. (How Alcohol Induces Atrial Tachyarrhythmias Study [HOLIDAY]; NCT01996943).

Two patients with long-standing atrial fibrillation (AF) refractory to medical management and with prior pulmonary vein isolation underwent a new hybrid epicardial/endocardial subxyphoid approach for AF ablation and left atrial appendage (LAA) ligation. Pulmonary vein and LA posterior wall isolation, as well as LAA exclusion were achieved in both patients. There were no procedural complications. Both patients remain in sinus rhythm. Both patients are off antiarrhythmic medications.

BackgroundAtrial refractoriness may be an important determinant of atrial fibrillation (AF) risk, but its measurement is not clinically accessible. Because the QT interval predicts incident AF and the atrium and ventricle share repolarizing ion currents, we investigated the association between an individual's QT interval and atrial effective refractory period (AERP).MethodsIn paroxysmal AF patients presenting for catheter ablation, the QT interval was measured from the surface 12-lead electrocardiogram. The AERP was defined as the longest S1-S2 coupling interval without atrial capture using a 600-ms drive cycle length.ResultsIn 28 patients, there was a positive correlation between QTc and mean AERP. After multivariate adjustment, a 1-ms increase in QTc predicted a 0.70-ms increase in AERP.ConclusionsThe QTc interval reflects the AERP, suggesting that the QTc interval may be used as a marker of atrial refractoriness relevant to assessing AF risk and mechanism-specific therapeutic strategies.

BackgroundArrhythmogenic right ventricular cardiomyopathy (ARVC) is a heritable arrhythmia syndrome entailing a high risk of sudden cardiac death. Discernment from benign arrhythmia disorders, particularly right ventricular outflow tract ventricular tachycardia (RVOT VT), may be challenging, providing an impetus to explore alternative modalities that may facilitate evaluation of patients with suspected ARVC.ObjectiveWe evaluated the role of equilibrium radionuclide angiography (ERNA) as a diagnostic tool for ARVC.MethodsERNA measures of ventricular synchrony-synchrony (S) and entropy (E)-were examined in patients with ARVC (n = 16), those with RVOT VT (n = 13), and healthy controls (n = 49). The sensitivity and specificity of ERNA parameters for ARVC diagnosis were compared with those of echocardiography (ECHO) and cardiovascular magnetic resonance (CMR).ResultsERNA right ventricular synchrony parameters in patients with ARVC (S = 0.91 ± 0.07; E = 0.61 ± 0.1) differed significantly from those in patients with RVOT VT (S = 0.99 ± 0.01 [P = .0015]; E = 0.46 ± 0.05 [P < .001]) and healthy controls (S = 0.97 ± 0.02 [P = .003]; E = 0.48 ± 0.07 [P = .001]). The sensitivity of ERNA synchrony parameters for ARVC diagnosis (81%) was higher than that for ECHO (38%; P = .033) and similar to that for CMR (69%; P = .162), while specificity was lower for ERNA (89%) than that for ECHO and CMR (both 100%; P = .008).ConclusionERNA right ventricular synchrony parameters can distinguish patients with ARVC from controls with structurally normal hearts, and its performance is comparable to that of ECHO and CMR for ARVC diagnosis. These findings suggest that ERNA may serve as a valuable imaging tool in the diagnostic evaluation of patients with suspected ARVC.

BackgroundLeft atrial appendage (LAA) exclusion has been performed in patients with atrial fibrillation (AF) to prevent thrombus formation and subsequent cardioembolic events. Left atrial electrical remodeling is a recognized factor in the recurrence of AF. The effects of LAA exclusion on P-wave characteristics and left atrial electrical remodeling have not been well described. The purpose of this study was to evaluate the effect of LAA ligation on P-wave morphology in patients with AF.Methods and resultsFifteen patients who were in sinus rhythm during the LAA ligation procedure were included in the study. We evaluated the P-wave characteristics, including P-wave duration, P-wave amplitude, PQ interval, and P-wave dispersion, before and after ligation. Eleven patients had paroxysmal AF and 4 patients had persistent AF (12 male patients and 3 female patients). P-wave duration immediately after ligation was significantly shorter compared with baseline in all limb leads except lead aVR (P

Wolff-Parkinson-White syndrome (WPW) is characteristically diagnosed by the presence of a short PR interval, a delta wave, and a wide QRS wave on the surface ECG. In the absence of these clear criteria, absent septal Q waves have been used as additional evidence suggestive of subtle preexcitation. We report a patient with WPW and manifest anteroseptal (AS) accessory pathway who had prominent septal Q waves on the surface ECG. This case highlights that physicians should be careful not to dismiss preexcitation in the presence of septal Q waves.

BackgroundThe arrhythmic role of the left atrial appendage (LAA) has been implicated in the maintenance of persistent atrial fibrillation. LAA isolation with catheter ablation has been successful but is limited by the risk of tamponade and electromechanical dissociation with the potential for LAA thrombus formation.ObjectiveTo assess whether LAA ligation results in LAA electrical isolation.MethodsA total of 68 patients with contraindication or intolerance to oral anticoagulation therapy underwent LAA ligation with the LARIAT suture delivery device. Patients had unipolar [n = 30(44%)] or bipolar [n = 38(56%)] voltage measurements pre- and post-LAA ligation.ResultsAll 68 patients underwent successful LAA ligation. There was a statistically significant reduction in the mean LAA voltage from pre-ligation (unipolar pre-ligation voltage 1.1 ± 0.53 mV; bipolar pre-ligation voltage 4.7 ± 2.83 mV) to post-ligation (unipolar post-ligation voltage 0.3 ± 0.38 mV; bipolar post-ligation voltage 0.6 ± 0.27 mV). Ninety-four percent of the patients had a reduction in the LAA voltage after the closure of the snare, with 10 of 30 (33%) of the patients having complete elimination of LAA voltage with the initial tightening of the suture. Pacing from the LAA after the closure of the snare resulted in lack of capture of the left atrium in 28 of 31 patients.ConclusionsThe snare closure of the LAA using the LARIAT device produces an acute reduction in the LAA voltage and inhibits the capture of the left atrium during LAA pacing. Future studies are needed to determine whether LAA ligation affects atrial fibrillation burden.

BackgroundTransseptal puncture is a critical step in achieving left atrial (LA) access for a variety of cardiac procedures. Although the mechanical Brockenbrough needle has historically been used for this procedure, a needle employing radiofrequency (RF) energy has more recently been approved for clinical use. We sought to investigate the comparative effectiveness of an RF versus conventional needle for transseptal LA access.Methods and resultsIn this prospective, single-blinded, controlled trial, 72 patients were randomized in a 1:1 fashion to an RF versus conventional (BRK-1) transseptal needle. In an intention-to-treat analysis, the primary outcome was time required for transseptal LA access. Secondary outcomes included failure of the assigned needle, visible plastic dilator shavings from needle introduction, and any procedural complication. The median transseptal puncture time was 68% shorter using the RF needle compared with the conventional needle (2.3 minutes [interquartile range {IQR}, 1.7 to 3.8 minutes] versus 7.3 minutes [IQR, 2.7 to 14.1 minutes], P = 0.005). Failure to achieve transseptal LA access with the assigned needle was less common using the RF versus conventional needle (0/36 [0%] versus 10/36 [27.8%], P < 0.001). Plastic shavings were grossly visible after needle advancement through the dilator and sheath in 0 (0%) RF needle cases and 12 (33.3%) conventional needle cases (P < 0.001). There were no differences in procedural complications (1/36 [2.8%] versus 1/36 [2.8%]).ConclusionsUse of an RF needle resulted in shorter time to transseptal LA access, less failure in achieving transseptal LA access, and fewer visible plastic shavings.

This article discusses a case of misdiagnosis from a smartwatch. A 60-year-old man received alerts on his wearable electronic device indicating that he may have atrial fibrillation. However, further testing revealed that he had a rare arrhythmia known as dual AV node non-reentrant tachycardia, or double fire. This condition can be misdiagnosed as supraventricular ectopy, ventricular ectopy, or atrial fibrillation. The article emphasizes the importance of careful physician review of rhythm strips to confirm the diagnosis, especially in cases where wearable devices are used. Treatment for double fire tachycardia typically involves radiofrequency ablation of the slow pathway. [Extracted from the article]

A 31-year old male presented with atrial fibrillation and ventricular preexcitation that was positive in leads V1-V4, negative in lead II, and positive in lead AVR. The patient was cardioverted and invasive electrophysiologic study was performed. Based on the ECG findings, the coronary sinus and its branches were interrogated during orthodromic atrioventricular reentrant tachycardia. The earliest local activation was seen in the true coronary sinus lumen at the bifurcation of the posterolateral branch. Radiofrequency energy application at this area led to loss of preexcitation. When localizing left septal and posterior accessory pathways, ventricular preexcitation that is both negative in II and positive in AVR has been shown in previous studies to be highly sensitive and specific for a subepicardial location. Therefore, investigation of the coronary sinus and its branches may allow for effective ablation without the need for left ventricular access.

Aims Kleefstra syndrome (KS), often diagnosed in early childhood, is a rare genetic disorder due to haploinsufficiency of EHMT1 and is characterized by neuromuscular and intellectual developmental abnormalities. Although congenital heart disease (CHD) is common, the prevalence of arrhythmias and CHD subtypes in KS is unknown. Methods and results Inspired by a novel case series of KS patients with atrial tachyarrhythmias in the USA, we evaluate the two largest known KS registries for arrhythmias and CHD: Radboudumc (50 patients) based on health record review at Radboud University Medical Center in the Netherlands and GenIDA (163 patients) based on worldwide surveys of patient families. Three KS patients (aged 17–25 years) presented with atrial tachyarrhythmias without manifest CHD. In the international KS registries, the median [interquartile range (IQR)] age was considerably younger: GenIDA/Radboudumc at 10/13.5 (12/13) years, respectively. Both registries had a 40% prevalence of cardiovascular abnormalities, the majority being CHD, including septal defects, vascular malformations, and valvular disease. Interestingly, 4 (8%) patients in the Radboudumc registry reported arrhythmias without CHD, including one atrial fibrillation (AF), two with supraventricular tachycardias, and one with non-sustained ventricular tachycardia. The GenIDA registry reported one patient with AF and another with chronic ectopic atrial tachycardia (AT). In total, atrial tachyarrhythmias were noted in six young KS patients (6/213 or 3%) with at least four (three AF and one AT) without structural heart disease. Conclusion In addition to a high prevalence of CHD, evolving data reveal early-onset atrial tachyarrhythmias in young KS patients, including AF, even in the absence of structural heart disease. [ABSTRACT FROM AUTHOR]