Use of the Wearable Cardioverter Defibrillator in High-Risk Populations.

The United States Food and Drug Administration has approved the wearable cardioverter defibrillator (WCD) for use in patients who are at high risk for sudden cardiac arrest (SCA) and who do not yet have an established indication for an implantation cardioverter defibrillator (ICD) or have contraindications for device implantation for various reasons. The WCD is typically used for primary prevention in (1) high-risk patients with reduced left ventricular ejection fraction (LVEF) ≤35 % after recent acute myocardial infarction (MI) during the 40-day ICD waiting period, (2) before and after coronary artery bypass graft or percutaneous coronary intervention during the 90-day ICD waiting period, (3) after recently diagnosed nonischemic dilated cardiomyopathy (NICM) during the 3- to 9-month medical therapy optimization period, or (4) for those with inherited proarrhythmic conditions such as long QT syndrome or hypertrophic cardiomyopathy. Unlike the automatic external defibrillator, the WCD does not require assistance from bystanders for therapy and conscious patients can delay or avert therapy with the use of response buttons. The WCD exhibits a small risk of inappropriate shock, mostly due to supraventricular tachycardia and/or electrical noise. Multiple non-randomized observational studies have shown high efficacy in detection and appropriate shock therapy for sustained ventricular tachyarrhythmias. This paper discusses the use of the WCD for prevention of SCA in patients with various cardiac substrates.

Device-Detected Atrial Fibrillation-Perils and Pitfalls: An Update.

Stroke and thromboembolism are catastrophic complications of atrial fibrillation (AF). Cardiac implantable electronic devices (CIED) with an atrial lead can reliably detect atrial high-rate events (AHRE). However, this correlation may be imperfect because of oversensing and undersensing of atrial signals and spurious arrhythmias. The critical duration, frequency, or overall burden of AHRE that increases stroke risk is still unknown; thus, the threshold level of AHRE (duration and frequency) that warrants anticoagulation in patients with CIED-detected AHRE is still unclear. This article reviews current literature on the risk of stroke with CIED-detected AHRE and raises questions that need further clarification.

The Wearable Cardioverter Defibrillator in Nonischemic Cardiomyopathy: A US National Database Analysis.

BACKGROUND: The wearable cardioverter defibrillator (WCD) is often used in patients at risk of sudden cardiac death (SCD) who are not yet candidates for an implantable cardioverter defibrillator (ICD). Newly diagnosed cardiomyopathy may be reversible, and a WCD may protect patients during the initial period of risk. We evaluate the benefit and compliance of the WCD in patients with nonischemic cardiomyopathy (NICM). METHODS: We reviewed a national database of patients with NICM who used WCDs and who self-reported a history of excess alcohol use, although other causes of cardiomyopathy could not be excluded. The database contained demographic data, initial ejection fraction (EF), reason for WCD prescription, compliance and use data, any detected arrhythmias, therapies, and reason for discontinuing WCD. Statistical analyses were performed using SAS, version 9.3 (SAS Institute, Cary, NC). RESULTS: Of the 127 patients, 88% were men with a mean age of 52.6 ± 11.0 years. The mean initial EF was 19.9% ± 7.4%. Patients wore the WCD for a median of 51 days and a median daily use of 18.0 hours per day. The most common reasons for discontinuing the WCD were improvement in EF (33%) or ICD implantation (23.6%). Seven patients (5.5%) had 9 sustained ventricular arrhythmia events, which were successfully treated with 100% conversion. There were 11 deaths (8.6%) during 100 days of follow-up. No deaths resulted from WCD shock failure or undersensing. CONCLUSIONS: NICM may have a significant risk of ventricular arrhythmias and death in the first few months. The WCD delivered appropriate therapy in 5.5% of patients. This study suggests that a WCD may be effective temporary prophylaxis for prevention of SCD in patients with newly diagnosed NICM.

Diagnostic approach of pulmonary disease in the HIV negative immunocompromised host.

The advances in medicine have resulted in increasing number of immunocompromised patients with complications related to their underlying disease or the treatment of these conditions. Pulmonary infectious and non-infectious conditions are a major cause of morbidity and mortality in these patients, and represent a diagnostic challenge. This article reviews the major conditions causing pulmonary symptoms in the HIV negative immunocompromised host. It also discusses the role of the different diagnostic methods, including the recent advances in non-invasive studies, in reaching a diagnosis of pulmonary disease in this patient population.