Ventricular pacing and myocardial function in patient with congenital heart block.

INTRODUCTION: Pacing-induced cardiomyopathy (PICM) is a potential complication of chronic right ventricular (RV) pacing, but its characterization in adult patients is often complicated by pre-existing cardiomyopathy. This study investigated the incidence of PICM in patients with congenital heart block (cHB) who have conduction disease from birth without confounding pre-existing cardiac conditions. METHODS AND RESULTS: This retrospective cohort analysis included 42 patients with cHB and baseline left ventricular ejection fraction (LVEF) ≥50%. Kaplan-Meier analysis was used to assess freedom from cardiomyopathy (defined as LVEF <50%) between paced and nonpaced patients. Patients were 26 ± 3 years old at first presentation, 64% were women and baseline LVEF was 60.0 ± 0.2%. Median follow-up from birth was 35 (interquartile range [IQR]: 20-42) years with a median of 6.7 years (IQR: 3.6-9.2) at our institution. Thirty-two patients received pacing at mean age 21 ± 3 years. Patients receiving a pacemaker (PM) were significantly more likely to develop a cardiomyopathy (p = .021) and no patient developed a cardiomyopathy in the absence of a PM. Four patients who developed a new cardiomyopathy were upgraded to biventricular pacing, leading to stabilization or improvement of LVEF. CONCLUSION: In a relatively young and healthy cHB cohort, RV pacing is associated with a higher risk of developing a cardiomyopathy. These data confirm the deleterious effects of RV pacing on myocardial function in patients without pre-existing structural cardiac disease and has clinical implications to the management of patients with cHB.

Noninvasive imaging of peripheral nerves.

Recent developments in the field of peripheral nerve imaging extend the capabilities of imaging modalities to assist in the diagnosis and treatment of patients with peripheral nerve maladies. Methods such as magnetic resonance imaging (MRI) and its derivative diffusion tensor imaging (DTI), ultrasound (US) and positron emission tomography (PET) are capable of assessing nerve structure and function following injury and relating the state of the nerve to electrophysiological and histological analysis. Of the imaging methods surveyed here, each offered unique and interesting advantages related to the field. MRI offered the opportunity to visualize immune activity on the injured nerve throughout the course of the regeneration process, and DTI offered numerical characterization of the injury and the ability to develop statistical bases for diagnosing injury. US extends imaging to the treatment phase by enabling more precise analgesic applications following surgery, and PET represents a novel method of assessing nerve injury through analysis of relative metabolism rates in injured and healthy tissue. Exciting new possibilities to enhance and extend the abilities of imaging methods are also discussed, including innovative contrast agents, some of which enable multimodal imaging approaches and present opportunities for treatment application.

Relative Contribution of Atrial Fibrillation to Outcomes of Patients With Cardiomyopathy Based on Severity of Left Ventricular Dysfunction.

In patients with left ventricular (LV) dysfunction, the risk of death or heart failure hospitalizations (HFHs) increases with worsening ejection fraction (EF). Whether the relative contribution of atrial fibrillation (AF) to outcomes is more pronounced in patients with worse EF is not confirmed. The present study aimed to investigate the relative influence of AF on the outcome of cardiomyopathy patients by severity of LV dysfunction. In this observational study, data from 18,003 patients with EF ≤50% seen at a large academic institution between 2011 and 2017 were analyzed. Patients were stratified by EF quartiles (EF<25%, 25%≤EF<35%, 35%≤EF<40%, and EF≥40%, for quartiles 1, 2, 3, and 4, respectively). and followed to the end point of death or HFH. Outcomes of AF versus non-AF patients were compared within each EF quartile. During a median follow-up of 3.35 years, 8,037 patients (45%) died and 7,271 (40%) had at least 1 HFH. Rates of HFH and all-cause mortality increased as EF decreased. The hazard ratios (HRs) of death or HFH for AF versus non-AF patients increased steadily with increasing EF (HR of 1.22, 1.27, 1.45, 1.50 for quartiles 1, 2, 3, and 4, respectively, p = 0.045) driven primarily by the risk of HFH (HR of 1.26, 1.45, 1.59, 1.69 for quartiles 1, 2, 3, and 4, respectively, p = 0.045). In conclusion, in patients with LV dysfunction, the detrimental influence of AF on the risk of HFH is more pronounced in those with more preserved EF. Mitigation strategies for AF with the goal of decreasing HFH may be more impactful in patients with more preserved LV function.

Guideline-Directed Medical Therapy and the Risk of Death in Primary Prevention Defibrillator Recipients.

BACKGROUND: Contemporary guideline-directed medical therapy (GDMT) confers a significant mortality benefit for patients with heart failure with reduced ejection fraction (HFrEF), as compared to GDMT prevalent at the time of landmark primary prevention implantable cardioverter-defibrillator (ICD) trials. The impact of modern era GDMT on survival in this population is unknown. OBJECTIVES: This study sought to investigate the impact of number of GDMT medications prescribed for HFrEF on all-cause mortality in recipients of primary prevention ICD. METHODS: A cohort of 4,972 recipients with primary prevention ICD (n = 3,210) or cardiac resynchronization therapy-defibrillator (CRT-D) (n = 1,762) was studied. The association of number of GDMT medications prescribed at the time of device implantation and all-cause mortality at 2 years post implantation was examined. RESULTS: In our primary prevention cohort, 5%, 20%, 52%, and 23% of patients were prescribed 0, 1, 2, or 3-4 GDMT medications, respectively. After risk adjustment for age, sex, ejection fraction, body mass index, the Elixhauser comorbidity score, the type of cardiomyopathy, and the year of device implantation, each additional GDMT conferred a reduction in the risk of death of 36% in recipients of ICD (HR: 0.64; P < 0.001) and 30% in recipients of CRT-D (HR: 0.70; P < 0.001). CONCLUSIONS: A higher number of prescribed GDMT medications is associated with an incremental 1-year survival in recipients of primary prevention ICD with or without CRT. Initiation of maximum number of tolerated GDMT medications should therefore be the goal for all patients with HFrEF. In the setting of robust GDMT, the risk versus benefit of a primary prevention ICD warrants re-examination in future studies.