Global LEADR pivotal trial results.

BACKGROUND: Implantable cardioverter-defibrillators last longer, and interest in reliable leads with targeted lead placement is growing. The OmniaSecure™ defibrillation lead is a novel small-diameter, catheter-delivered lead designed for targeted placement, based on the established SelectSecure SureScan MRI Model 3830 lumenless pacing lead platform. OBJECTIVE: This trial assessed safety and efficacy of the OmniaSecure defibrillation lead. METHODS: The worldwide LEADR pivotal clinical trial enrolled patients indicated for de novo implantation of a primary or secondary prevention implantable cardioverter-defibrillator/cardiac resynchronization therapy defibrillator, all of whom received the study lead. The primary efficacy end point was successful defibrillation at implantation per protocol. The primary safety end point was freedom from study lead-related major complications at 6 months. The primary efficacy and safety objectives were met if the lower bound of the 2-sided 95% credible interval was >88% and >90%, respectively. RESULTS: In total, 643 patients successfully received the study lead, and 505 patients have completed 12-month follow-up. The lead was placed in the desired right ventricular location in 99.5% of patients. Defibrillation testing at implantation was completed in 119 patients, with success in 97.5%. The Kaplan-Meier estimated freedom from study lead-related major complications was 97.1% at 6 and 12 months. The trial exceeded the primary efficacy and safety objective thresholds. There were zero study lead fractures and electrical performance was stable throughout the mean follow-up of 12.7 ± 4.8 months (mean ± SD). CONCLUSION: The OmniaSecure lead exceeded prespecified primary end point performance goals for safety and efficacy, demonstrating high defibrillation success and a low occurrence of lead-related major complications with zero lead fractures.

Limitation of standard ECG criteria to localize an outflow tract PVC.

Multiple ECG algorithms exist to localize outflow tract PVCs. They can be invaluable in pre-procedure planning and patient counseling. We describe a case where the published algorithm for PVC localization did not predict the site of origin and successful ablation site. This case highlights the strengths and limitations of established ECG PVC localization algorithms.

Use of a Smartwatch for Assessment of the QT Interval in Outpatients with Coronavirus Disease 2019.

The coronavirus disease 2019 (COVID-19) pandemic has necessitated rapid implementation of innovative strategies to manage patients remotely to help reduce the risk of community and nosocomial transmission. This case demonstrates the use of an Apple Watch (Apple, Cupertino, CA, USA) to monitor for arrhythmias and QT prolongation in a patient with COVID-19 during home isolation.

Bradyarrhythmias in patients with COVID-19: Marker of poor prognosis?

BACKGROUND: Despite descriptions of various cardiovascular manifestations in patients with coronavirus disease 2019 (COVID-19), there is a paucity of reports of new onset bradyarrhythmias, and the clinical implications of these events are unknown. METHODS: Seven patients presented with or developed severe bradyarrhythmias requiring pacing support during the course of their COVID-19 illness over a 6-week period of peak COVID-19 incidence. A retrospective review of their presentations and clinical course was performed. RESULTS: Symptomatic high-degree heart block was present on initial presentation in three of seven patients (43%), and four patients developed sinus arrest or paroxysmal high-degree atrioventricular block. No patients in this series demonstrated left ventricular systolic dysfunction or acute cardiac injury, whereas all patients had elevated inflammatory markers. In some patients, bradyarrhythmias occurred prior to the onset of respiratory symptoms. Death from complications of COVID-19 infection occurred in 57% (4/7) patients during the initial hospitalization and in 71% (5/7) patients within 3 months of presentation. CONCLUSIONS: Despite management of bradycardia with temporary (3/7) or permanent leadless pacemakers (4/7), there was a high rate of short-term morbidity and death due to complications of COVID-19. The association between new-onset bradyarrhythmias and poor outcomes may influence management strategies for acutely ill patients with COVID-19.

Early recurrence of atrial fibrillation after pulmonary vein isolation: a comparative analysis between cryogenic and contact force radiofrequency ablation.

BACKGROUND: Early recurrence (ER) of atrial fibrillation (AF) within 90 days post-ablation is observed in up to 50% of patients and has been attributed to transient inflammation. The importance of ER in current era of pulmonary vein isolation (PVI) with cryoballoon ablation (CBA) and contact-force catheter radiofrequency ablation (cfRFA) has not been clearly reported. In addition, it is not known whether there are differences between types of ablation energy used during PVI. METHODS: Study population was drawn from a prospective multicenter database of AF ablation. Consecutive patients undergoing first-time ablation with PVI alone, using either second-generation CBA or cfRFA catheters were included. Patients were followed at 0.5, 3, 6, and 12 months to assess recurrence. Predictors of late recurrence (LR), defined as recurrence outside the blanking period, were assessed by Cox proportional hazards regression models. Freedom from LR was calculated and compared between two groups using the Kaplan-Meier method and log-rank test. RESULTS: Study cohort included 300 patients (1:1 CBA:RFA, age 63.6 ± 10.3 years, 67% male). There were no baseline characteristic differences between the CBA and cfRFA groups. ER occurred in 23.3% and 16.7% of patients in the CBA and cfRFA groups, respectively (p = 0.149). One-year freedom from LR was similar for both groups (72.7% CBA vs. 78% cfRFA, p = 0.287). Fifty-two patients (25 CBA and 27 cfRFA) underwent repeat ablation and no difference in durability of PVI was found. ER was the only common independent predictor of LR for either group and for the entire cohort (HR 2.3). CONCLUSIONS: In our series of AF ablation using second-generation cryoballoon and contact-force RFA catheters, recurrence in the "blanking period" is seen in 20% and remains predictive of late recurrence irrespective of the energy used.

Downstream overdrive pacing and intracardiac concealed fusion to guide rapid identification of atrial tachycardia after atrial fibrillation ablation.

Aims: Atrial tachycardia (AT) related to atrial fibrillation (AF) ablation frequently poses a diagnostic challenge. Downstream overdrive pacing (DOP) can be used to rapidly detect reentry and assess proximity of a pacing site to an AT circuit or focus. We hypothesized that systematic DOP using multielectrode catheters would facilitate AT mapping. Methods and results: DOP identified constant fusion when the post-pacing interval (PPI)-tachycardia cycle length (TCL) <40 ms and stimulus to adjacent upstream atrial electrogram interval >75% of TCL. Mapping was performed as follows: (i) CS DOP, (ii) DOP at left atrial (LA) roof, (iii) DOP at selected LA sites based on prior DOP attempts, and (iv) mapping and ablation at regions of fractionated electrograms in region of AT. Activation mapping was performed at operator discretion. AT diagnosis was confirmed by successful ablation or additional mapping when ablation was unsuccessful. Fifty consecutive patients with sustained AT underwent mapping of 68 ATs, of whom 42 (62%) were macroreentrant, 19 were locally reentrant (28%), and 7 (10%) were focal. AT was correctly identified with a median of three DOP attempts. All macroreentrant ATs were identified with ≤6 DOP attempts. One AT (1.6%) was terminated by DOP, and three ATs (4.8%) required activation mapping. Intracardiac concealed fusion was seen in 26 ATs (38%), each of which was successfully ablated. Conclusion: Reentry could be demonstrated in a substantial majority of AF ablation-related AT. A stepwise diagnostic approach using DOP and recognition of intracardiac concealed fusion can be used to rapidly identify and ablate reentrant AT.

Determinants of Heparin Dosing and Complications in Patients Undergoing Left Atrial Ablation on Uninterrupted Rivaroxaban.

BACKGROUND: Patients on rivaroxaban have variable international normalized ratios (INRs) but it is uncertain if INR impacts procedural heparin requirement during left atrial ablation. We sought to examine the determinants of heparin dosing in this patient population. METHODS: We reviewed consecutive patients who received rivaroxaban within 24 hours of left atrial ablation and compared them to patients on uninterrupted warfarin. The determinants of heparin requirement were evaluated using regression analysis. We then tested a weight-based heparin dose prospectively in rivaroxaban patients. RESULTS: There were 258 patients on rivaroxaban and 213 on warfarin. The mean INR was 1.4 in the rivaroxaban group and 2.3 in the warfarin group (P < 0.01). To achieve an activated clotting time (ACT) >350 seconds, rivaroxaban patients required significantly more heparin (166.9 vs. 78.3 units/kg, P < 0.001). In the rivaroxaban group, body weight was the strongest predictor of heparin dose (r = 0.52), while INR was weakly correlated (r = -0.21). In the prospective group, 25 patients were given an initial heparin dose of 120 units/kg with 22/25 (88%) achieving an ACT > 300 seconds. There were seven and three cases of pericardial effusion in rivaroxaban and warfarin patients, respectively (P = 0.41). The average volume drained in the rivaroxaban group was elevated (988.6 vs. 275.0 mL, P = 0.21). CONCLUSIONS: Body weight is the strongest predictor of procedural heparin requirement during left atrial ablation in patients on uninterrupted rivaroxaban, even in those with an elevated INR. A heparin dose of 120 units/kg achieves an ACT > 300 seconds in the majority of patients. In cases of pericardial effusion, bleeding may be prolonged.

Impedance-guided Radiofrequency Ablation: Using Impedance to Improve Ablation Outcomes.

Despite the achievement of acute conduction block during catheter ablation, the recovery of conduction at previously ablated sites remains a primary factor implicated in arrhythmia recurrence after initial ablation. Real-time markers of adequate ablation lesion creation are needed to ensure durable ablation success. However, the assessment of acute lesion formation is challenging, and requires interpretation of surrogate markers of lesion creation that are frequently unreliable. Careful monitoring of impedance changes during radiofrequency catheter ablation has emerged as a highly specific marker of local tissue destruction. Ablation strategies guided by close impedance monitoring during ablation applications have been demonstrated to achieve high levels of success for ablation of atrial fibrillation. Impedance decrease during ablation may therefore be used as an additional endpoint beyond acute conduction block, in order to improve the durability of ablation lesions. In this manuscript, available methods of real-time lesion assessment are reviewed, and the rationale and technique for impedance-guided ablation are described.

Selective His-bundle Pacing May Preserve Intrinsic Repolarization as Well as Depolarization.

A 79-year-old man with chronic atrial fibrillation underwent single-chamber His-bundle pacemaker implantation. The post-implant electrocardiogram (ECG) demonstrated selective His-bundle capture, with a narrow paced QRS and repolarization pattern similar to that of the baseline ECG. Furthermore, repolarization changes prototypic of ventricular pacing did not occur with selective His-bundle capture. While His-bundle pacing, with or without selective His-bundle capture, can preserve physiologic patterns of depolarization, only His-bundle selective pacing can preserve intrinsic ST- and T-wave patterns. Thus, the maintenance of physiologic repolarization may have various advantages, including accurate interpretation of ECG changes that are not generally interpretable in the setting of ventricular pacing.

Sites With Small Impedance Decrease During Catheter Ablation for Atrial Fibrillation Are Associated With Recovery of Pulmonary Vein Conduction.

OBJECTIVE: To correlate impedance decrease during atrial fibrillation (AF) ablation with lesion durability and PV conduction recovery demonstrated during redo procedures. BACKGROUND: Markers of successful ablation beyond acute conduction block are needed to improve durability of pulmonary vein (PV) isolation (PVI). Local impedance decrease resulting from ablation is a real-time marker of tissue heating and is correlated with lesion creation. METHODS: Impedance changes associated with point-by-point radiofrequency ablation in the PV antra were recorded during 167 consecutive first-time AF ablations. During clinically indicated redo procedures, sites of recovered PV conduction were identified, and were correlated with the impedance change achieved during ablation at these locations during the initial procedure. RESULTS: Redo procedures were performed in 28 patients, in whom 19 sites of recovered PV conduction were documented. Most sites of PV reconnection (58%) occurred along the posterior PV antra. Ablation resulting in impedance decrease <10 ohms during the initial procedure was present in 89% (17/19) of sites with conduction recovery. Regions with adjacent ablation resulting in impedance decrease <10 ohms were associated with a higher rate of conduction recovery (37% vs. 1.5%, P < 0.001). Likewise, patients with PV conduction recovery demonstrated during redo procedure (Group 1) had larger regions where ablation resulted in <10 ohm impedance decrease than patients without PV conduction recovery (Group 2) (21.9 ± 15.5 mm vs. 11.5 ± 2.1 mm, P < 0.01). CONCLUSION: Recovered PV conduction occurs predominantly in regions where adjacent ablation applications result in impedance decreases <10 ohms. Impedance-guided ablation strategies may improve durability of PVI.

Recurrence of Atrial Arrhythmias Despite Persistent Pulmonary Vein Isolation After Catheter Ablation for Atrial Fibrillation: A Case Series.

OBJECTIVES: The aim of this study was to categorize arrhythmia mechanisms and to summarize ablation strategies in patients with persistent pulmonary vein isolation (PVI) at the time of redo procedures. BACKGROUND: Persistent PVI is more frequently seen in patients undergoing redo procedures for recurrent atrial arrhythmias after catheter ablation for atrial fibrillation (AF). METHODS: Consecutive patients who underwent their first AF ablation procedures at Brigham and Women's Hospital were screened and included if they had persistent isolation of all pulmonary veins at the time of redo procedures. RESULTS: Of 300 consecutive patients undergoing first AF ablation procedures, redo procedures were performed in 63 (21%), and 26 patients (9%) had persistent PVI. Of those, 11 had recurred with AF and 15 with organized atrial tachycardia (AT). During the index procedure, linear ablation was performed in 46% of patients with recurrent AF and 93% with recurrent organized AT (p = 0.020). At the time of last follow-up, 2 of 10 patients (20%) in the AF group and 10 of 15 patients (67%) in AT group were in sinus rhythm, without class I or III antiarrhythmic drugs (p = 0.022). CONCLUSIONS: Patients with recurrence of atrial arrhythmia despite persistent PVI frequently present with organized AT. Linear ablation during the index procedure is associated with recurrence of organized AT. Recurrence rates after redo procedures were higher if patients had recurrent AF after the index procedure, and these patients often presented with AF again. Patients with recurrent AF despite persistent PVI may represent a population with lower success rates of catheter ablation.

Better outcome of ablation for sustained outflow-tract ventricular tachycardia when tachycardia is inducible.

AIMS: In patients presenting with spontaneous sustained ventricular tachycardia (VT) from the outflow-tract region without overt structural heart disease ablation may target premature ventricular contractions (PVCs) when VT is not inducible. We aimed to determine whether inducibility of VT affects ablation outcome. METHODS AND RESULTS: Data from 54 patients (31 men; age, 52 ± 13 years) without overt structural heart disease who underwent catheter ablation for symptomatic sustained VT originating from the right- or left-ventricular outflow region, including the great vessels. A single morphology of sustained VT was inducible in 18 (33%, SM group) patients, and 11 (20%) had multiple VT morphologies (MM group). VT was not inducible in 25 (46%) patients (VTni group). After ablation, VT was inducible in none of the SM group and in two (17%) patients in the MM group. In the VTni group, ablation targeted PVCs and 12 (48%) patients had some remaining PVCs after ablation. During follow-up (21 ± 19 months), VT recurred in 46% of VTni group, 40% of MM inducible group, and 6% of the SM inducible group (P = 0.004). Analysis of PVC morphology in the VTi group further supported the limitations of targeting PVCs in this population. CONCLUSION: Absence of inducible VT and multiple VT morphologies are not uncommon in patients with documented sustained outflow-tract VT without overt structural heart disease. Inducible VT is associated with better outcomes, suggesting that attempts to induce VT to guide ablation are important in this population.

Correlates and prognosis of early recurrence after catheter ablation for ventricular tachycardia due to structural heart disease.

BACKGROUND: Catheter ablation for ventricular tachycardia (VT) from structural heart disease has a significant risk of recurrence, but the optimal duration for in-hospital monitoring is not defined. This study assesses the timing, correlates, and prognostic significance of early VT recurrence after ablation. METHODS AND RESULTS: Of 370 patients (313 men; aged 63.0±13.2 years) who underwent a first radiofrequency ablation for sustained monomorphic VT associated with structural heart disease from 2008 to 2012, sustained VT recurred in 81 patients (22%) within 7 days. In multivariable analysis, early recurrence was associated with New York Heart Association classification ≥III (odds ratio [OR] 1.90, 95% confidence interval [CI] 1.03-3.48; P=0.04), dilated cardiomyopathy (OR 1.93, 95% CI 1.03-3.57; P=0.04), prevalence of VT storm before the procedure (OR 2.62, 95% CI 1.48-4.65; P=0.001), a greater number of induced VTs (OR 1.24, 95% CI 1.07-1.45; P=0.006), and acute failure or no final induction test (OR 1.88, 95% CI 1.03-3.40; P=0.04). During a median of 2.5 (1.2, 4.0) years of follow-up, early VT recurrence was an independent correlates of mortality (hazard ratio 2.59, 95% CI 1.52-4.34; P=0.0005). CONCLUSIONS: Patients who have early recurrences of VT after ablation are a high risk group who may be identifiable from their clinical profile. Further study is warranted to define the optimal treatment strategies for this patient group.

Cardiac resynchronization therapy: who benefits?

BACKGROUND: Cardiac resynchronization therapy (CRT) has been well established in multiple large trials to improve symptoms, hospitalizations, reverse remodeling, and mortality in well-selected patients with heart failure when used in addition to optimal medical therapy. Updated consensus guidelines outline patients in whom such therapy is most likely to result in substantial benefit. However, pooled data have demonstrated that only approximately 70% of patients who qualify for CRT based on current indications actually respond favorably. In addition, current guidelines are based on outcomes from the carefully selected patients enrolled in clinical trials, and almost certainly fail to include all patients who might benefit from CRT. FINDINGS: The identification of patients most likely to benefit from CRT requires consideration of factors beyond these standard criteria, QRS morphology with particular consideration in patients with left bundle-branch block pattern, extent of QRS prolongation, etiology of cardiomyopathy, rhythm, and whether the patient requires or will eventually need antibradycardia pacing. In addition, the baseline severity of functional impairment may influence the type of benefit to be expected from CRT; for example, New York Heart Association class I patients may derive long-term benefit in cardiac structure and function, but no benefit in symptoms or hospitalizations can be reasonably expected. In contrast, certain New York Heart Association class IV patients may be too sick to realize long-term mortality benefits from CRT, but improvements in hemodynamic profile and functional capacity may represent vital advances in this population. CONCLUSION: This review evaluates the evidence regarding the various factors that can predict positive or even detrimental responses to CRT, to help better determine who benefits most from this evolving therapy.

Clinical outcomes after repair of left atrial esophageal fistulas occurring after atrial fibrillation ablation procedures.

BACKGROUND: The initial experience with left atrial esophageal fistula (LAEF) secondary to atrial fibrillation (AF) ablation procedures revealed a near-universal mortality. A comprehensive description of the principles of LAEF repair in the modern era and its resulting impact on morbidity and mortality are lacking in the literature. OBJECTIVE: To describe the presentation, surgical management, and outcomes of patients with LAEF. METHODS: A retrospective cohort analysis of 29 patients was performed, including previously unpublished cases of surgically repaired LAEF from 4 institutions (n = 6), and all published cases of surgically repaired (n = 16) or stented (n = 7) LAEF. RESULTS: The mean age was 55 ± 13 years, and 75% were men who were undergoing radiofrequency energy catheter ablation (n = 26), cryoablation (n = 1), high-intensity focused ultrasound ablation (n = 1), and surgical mini-MAZE procedure (n = 1) and presented 30 ± 12 days postablation procedure. Overall, 55% of the patients receiving an intervention for LAEF died (41% surgical repair; 100% stent). Patients who did not receive primary esophageal repair were more likely to experience postoperative complications, including mediastinitis, need for percutaneous endoscopic gastrostomy (PEG) feeds, esophageal stent, or death (P = .05). In addition, interposing tissue between the repaired esophagus and the left atrium resulted in fewer postoperative complications (P = .02). CONCLUSIONS: While improved relative to initial reports, mortality associated with LAEF remains high after corrective intervention. Primary esophageal repair with the placement of tissue between the repaired esophagus and the left atrium may result in lower morbidity and mortality.

Mitral apparatus assessment by delayed enhancement CMR: relative impact of infarct distribution on mitral regurgitation.

OBJECTIVES: This study sought to assess patterns and functional consequences of mitral apparatus infarction after acute myocardial infarction (AMI). BACKGROUND: The mitral apparatus contains 2 myocardial components: papillary muscles and the adjacent left ventricular (LV) wall. Delayed-enhancement cardiac magnetic resonance (DE-CMR) enables in vivo study of inter-relationships and potential contributions of LV wall and papillary muscle infarction (PMI) to mitral regurgitation (MR). METHODS: Multimodality imaging was performed: CMR was used to assess mitral geometry and infarct pattern, including 3D DE-CMR for PMI. Echocardiography was used to measure MR. Imaging occurred 27 ± 8 days after AMI (CMR, echocardiography within 1 day). RESULTS: A total of 153 patients with first AMI were studied; PMI was present in 30% (n = 46 [72% posteromedial, 39% anterolateral]). When stratified by angiographic culprit vessel, PMI occurred in 65% of patients with left circumflex, 48% with right coronary, and only 14% of patients with left anterior descending infarctions (p <0.001). Patients with PMI had more advanced remodeling as measured by LV size and mitral annular diameter (p <0.05). Increased extent of PMI was accompanied by a stepwise increase in mean infarct transmurality within regional LV segments underlying each papillary muscle (p <0.001). Prevalence of lateral wall infarction was 3-fold higher among patients with PMI compared to patients without PMI (65% vs. 22%, p <0.001). Infarct distribution also impacted MR, with greater MR among patients with lateral wall infarction (p = 0.002). Conversely, MR severity did not differ on the basis of presence (p = 0.19) or extent (p = 0.12) of PMI, or by angiographic culprit vessel. In multivariable analysis, lateral wall infarct size (odds ratio 1.20/% LV myocardium [95% confidence interval: 1.05 to 1.39], p = 0.01) was independently associated with substantial (moderate or greater) MR even after controlling for mitral annular (odds ratio 1.22/mm [1.04 to 1.43], p = 0.01), and LV end-diastolic diameter (odds ratio 1.11/mm [0.99 to 1.23], p = 0.056). CONCLUSIONS: Papillary muscle infarction is common after AMI, affecting nearly one-third of patients. Extent of PMI parallels adjacent LV wall injury, with lateral infarction-rather than PMI-associated with increased severity of post-AMI MR.