Left bundle branch pacing vs ventricular septal pacing for cardiac resynchronization therapy.

Background: The outcomes of left bundle branch pacing (LBBP) and left ventricular septal pacing (LVSP) in patients with heart failure remain to be learned. Objective: The objective of this study was to assess the echocardiographic and clinical outcomes of LBBP, LVSP, and deep septal pacing (DSP). Methods: This retrospective study included patients who met the criteria for cardiac resynchronization therapy (CRT) and underwent attempted LBBP in 5 Mayo centers. Clinical, electrocardiographic, and echocardiographic data were collected at baseline and follow-up. Results: A total of 91 consecutive patients were included in the study. A total of 52 patients had LBBP, 25 had LVSP, and 14 had DSP. The median follow-up duration was 307 (interquartile range 208, 508) days. There was significant left ventricular ejection fraction (LVEF) improvement in the LBBP and LVSP groups (from 35.9 ± 8.5% to 46.9 ± 10.0%, P < .001 in the LBBP group; from 33.1 ± 7.5% to 41.8 ± 10.8%, P < .001 in the LVSP group) but not in the DSP group. A unipolar paced right bundle branch block morphology during the procedure in lead V1 was associated with higher odds of CRT response. There was no significant difference in heart failure hospitalization and all-cause deaths between the LBBP and LVSP groups. The rate of heart failure hospitalization and all-cause deaths were increased in the DSP group compared with the LBBP group (hazard ratio 5.10, 95% confidence interval 1.14-22.78, P = .033; and hazard ratio 7.83, 95% confidence interval 1.38-44.32, P = .020, respectively). Conclusion: In patients undergoing CRT, LVSP had comparable CRT outcomes compared with LBBP.

Impact of timing of transvenous lead removal on outcomes in infected cardiac implantable electronic devices.

BACKGROUND: Cardiovascular implantable electronic device (CIED) infections are associated with increased mortality and morbidity. OBJECTIVE: This study sought to evaluate the impact of early vs delayed transvenous lead removal (TLR) on in-hospital mortality and outcomes in patients with CIED infection. METHODS: Using the nationally representative, all payer, Nationwide Readmissions Database, we evaluated patients undergoing TLR for CIED infection between January 1, 2016, and December 31, 2018. The timing of TLR was determined on the basis of hospitalization days after the initial admission for CIED infection. The impact of early (≤7 days) vs delayed (>7 days) TLR on mortality and major adverse events was studied. RESULTS: Of the 12,999 patients who underwent TLR for CIED infection, 8834 (68%) underwent early TLR and 4165 (32%) underwent delayed TLR. Delayed TLR was associated with a significant increase in in-hospital mortality (8.3% vs 3.5%; adjusted odds ratio 1.70; 95% confidence interval 1.43-2.03; P < .001). Subgroup analysis of patients with CIED infection and systemic infection showed that delayed TLR in patients with systemic infection was associated with a higher rate of in-hospital mortality compared with early TLR (10.4% vs 7.5%; adjusted odds ratio 1.24; 95% confidence interval 1.04-1.49; P < .019). Delayed TLR was also associated with significantly higher adjusted odds of major adverse events and postprocedural length of stay. CONCLUSION: These data suggest that delayed TLR in patients with CIED infection is associated with increased in-hospital mortality and major adverse events, especially in patients with systemic infection.

Catheter ablation related mitral valve injury: the importance of early recognition and rescue mitral valve repair.

INTRODUCTION: An increasing number of catheter ablations involve the mitral annular region and valve apparatus, increasing the risk of catheter interaction with the mitral valve (MV) complex. We review our experience with catheter ablation-related MV injury resulting in severe mitral regurgitation (MR) to delineate mechanisms of injury and outcomes. METHODS: We searched the Mayo Clinic MV surgical database over a 19-year period (1993-2012) and the electrophysiologic procedures database over a 23-year period (1990-2013) and identified 9 patients with catheter ablation related MV injury requiring clinical intervention. RESULTS: Indications for ablation included atrial fibrillation (AF) [n = 4], ventricular tachycardia (VT) [n = 3], and left-sided accessory pathways [n = 2]. In all 4 AF patients, a circular mapping catheter entrapped in the MV apparatus was responsible for severe MR. In all 3 VT patients, radiofrequency energy delivery led to direct injury to the MV apparatus. In the 2 patients with accessory pathways, both mechanisms were involved (1 per patient). Six patients required surgical intervention (5 MV repair, 1 catheter removal). One patient developed severe functional MR upon successful endovascular catheter disentanglement that improved spontaneously. Two VT patients with persistent severe postablation MR were managed nonsurgically, 1 of whom died 3 months postprocedure. CONCLUSION: Circular mapping catheter entrapment and ablation at the mitral annulus are the most common etiologies of MV injury during catheter ablation. Close surveillance of the MV is needed during such procedures and early surgical repair is important for successful salvage if significant injury occurs.

Brief sympathetic activation precedes the development of ventricular tachycardia and ventricular fibrillation in hibernating myocardium.

BACKGROUND: Hibernating myocardium develops inhomogeneity in myocardial sympathetic innervation with spontaneous sudden cardiac death (SCD) because of ventricular fibrillation (VF). The triggers and prodromal arrhythmias initiating SCD in this substrate are unknown. METHODS: Swine chronically instrumented with a proximal left anterior descending coronary artery stenosis underwent placement of an implantable telemetry unit capable of continuously recording digitized electrocardiogram and left ventricular pressure signals at 1 kHz in conscious unrestrained animals for periods of up to 5 months. RESULTS: Spontaneous SCD (n = 10) was initiated by a close-coupled premature ventricular contraction followed by ventricular tachycardia (VT) that degenerated into VF during brief sympathetic activation. Peak heart rates were similar in animals that developed SCD vs survivors (250 +/- 12 vs 261 +/- 6 bpm). Electrocardiogram evidence of ischemia preceding VT/VF occurred in only 1 animal, and there was no significant infarction. CONCLUSIONS: Spontaneous VT/VF in hibernating myocardium develops during brief sympathetic activation with only rare evidence of acute ischemia. This supports the notion that the regional remodeling accompanying hibernating myocardium may be a novel substrate for the development of SCD in chronic ischemic heart disease.

Prediction of arrhythmic events with positron emission tomography: PAREPET study design and methods.

BACKGROUND: In medically-treated patients with ischemic cardiomyopathy, myocardial viability is associated with a worse prognosis than scar. The risk is especially great with hibernating myocardium (chronic regional dysfunction with reduced resting flow), and the excess mortality appears to be due to sudden cardiac death (SCD). Hibernating myocardium also results in sympathetic nerve dysfunction, which has been independently associated with risk of SCD. OBJECTIVES: PAREPET is a prospective, observational cohort study funded by NHLBI. It is designed to determine whether hibernating myocardium and/or inhomogeneity of sympathetic innervation by positron emission tomography imaging identifies patients with ischemic cardiomyopathy who are at high risk for SCD and cardiovascular mortality. METHODS: Patients with documented ischemic cardiomyopathy, an ejection fraction of