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.

Long-term outcomes with abandoning versus extracting sterile leads: A 10-year population-based study.

BACKGROUND: Long-term outcomes of sterile lead management strategies of lead abandonment (LA) or transvenous lead extraction (TLE) remain unclear. METHODS: We performed a retrospective study of a population residing in southeastern Minnesota with follow-up at the Mayo Clinic and its health systems. Patients who underwent LA or TLE of sterile leads from January 1, 2000, to January 1, 2011, and had follow-up for at least 10 years or until their death were included. RESULTS: A total of 172 patients were included in the study with 153 patients who underwent LA and 19 who underwent TLE for sterile leads. Indications for subsequent lead extraction arose in 9.1% (n = 14) of patients with initial LA and 5.3% (n = 1) in patients with initial TLE, after an average of 7 years. Moreover, 28.6% of patients in the LA cohort who required subsequent extraction did not proceed with the extraction, and among those who proceeded, 60% had clinical success and 40% had a clinical failure. Subsequent device upgrades or revisions were performed in 18.3% of patients in the LA group and 31.6% in the TLE group, with no significant differences in procedural challenges (5.2% vs. 5.3%). There was no difference in 10-year survival probability among the LA group and the TLE group (p = .64). CONCLUSION: An initial lead abandonment strategy was associated with more complicated subsequent extraction procedures compared to patients with an initial transvenous lead extraction strategy. However, there was no difference in 10-year survival probability between both lead management approaches.

Causes of Early Mortality After Transvenous Lead Removal.

BACKGROUND: Recognition of the causes of early mortality (≤30 days) after transvenous lead removal (TLR) is an essential step for the development of quality improvement programs. OBJECTIVES: This study sought to determine the causes of early mortality after TLR and to further understand the circumstances surrounding death after TLR. METHODS: A retrospective analysis was performed of all patients undergoing TLR from January 1, 2001, to January 1, 2021, at the Mayo Clinic (Rochester, Minnesota; Phoenix, Arizona; and Jacksonville, Florida). Causes of death were identified through a detailed chart review of the electronic health record from within the Mayo Clinic system and outside records when available. The causes of death were further characterized based on whether it was related to the TLR procedure. RESULTS: A total of 2,319 patients were included in the study. The overall 30-day all-cause mortality rate was 3% (n = 69). Among all 30-day deaths, infection was the most common primary cause of death (42%). This was followed by decompensated heart failure (17%), procedure-related death (10%), sudden cardiac arrest (7%), and respiratory failure (6%). The 30-day mortality rate directly due to complications associated with the TLR procedure was 0.3%. One-third of deaths (33%) occurred after discharge from the index hospitalization; among these, 43% were readmitted before their death, 35% died at home or at a nursing facility, and 22% were discharged on comfort care and died in hospice. The main reasons for readmission before death were sepsis and decompensated heart failure. CONCLUSIONS: The majority (90%) of 30-day mortality after TLR was not due to complications associated with TLR procedures. The primary causes were infection and decompensated heart failure. This highlights the importance of increased emphasis on postprocedure management of infection and heart failure to reduce postoperative mortality, including after hospital discharge.

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.

Guidance on Short-Term Management of Atrial Fibrillation in Coronavirus Disease 2019.

Atrial fibrillation is a common clinical manifestation in hospitalized patients with coronavirus disease 2019 (COVID-19). Medications used to treat atrial fibrillation, such as antiarrhythmic drugs and anticoagulants, may have significant drug interactions with emerging COVID-19 treatments. Common unintended nontherapeutic target effects of COVID-19 treatment include potassium channel blockade, cytochrome P 450 isoenzyme inhibition or activation, and P-glycoprotein inhibition. Drug-drug interactions with antiarrhythmic drugs and anticoagulants in these patients may lead to significant bradycardia, ventricular arrhythmias, or severe bleeding. It is important for clinicians to be aware of these interactions, drug metabolism changes, and clinical consequences when choosing antiarrhythmic drugs and anticoagulants for COVID-19 patients with atrial fibrillation. The objective of this review is to provide a practical guide for clinicians who are managing COVID-19 patients with concomitant atrial fibrillation.

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

Targeting nucleotide-requiring enzymes: implications for diazoxide-induced cardioprotection.

Modulation of mitochondrial respiratory chain, dehydrogenase, and nucleotide-metabolizing enzyme activities is fundamental to cellular protection. Here, we demonstrate that the potassium channel opener diazoxide, within its cardioprotective concentration range, modulated the activity of flavin adenine dinucleotide-dependent succinate dehydrogenase with an IC50 of 32 microM and reduced the rate of succinate-supported generation of reactive oxygen species (ROS) in heart mitochondria. 5-Hydroxydecanoic fatty acid circumvented diazoxide-inhibited succinate dehydrogenase-driven electron flow, indicating a metabolism-dependent supply of redox equivalents to the respiratory chain. In perfused rat hearts, diazoxide diminished the generation of malondialdehyde, a marker of oxidative stress, which, however, increased on diazoxide washout. This effect of diazoxide mimicked ischemic preconditioning and was associated with reduced oxidative damage on ischemia-reperfusion. Diazoxide reduced cellular and mitochondrial ATPase activities, along with nucleotide degradation, contributing to preservation of myocardial ATP levels during ischemia. Thus, by targeting nucleotide-requiring enzymes, particularly mitochondrial succinate dehydrogenase and cellular ATPases, diazoxide reduces ROS generation and nucleotide degradation, resulting in preservation of myocardial energetics under stress.