Introduction to atrial fibrillation and heart failure: a mutually noxious association.

Abstract

The complex interactions between atrial fibrillation (AF) and congestive heart failure (CHF) have been long and vigorously debated, with few firm conclusions reached. Several unresolved issues persist, beginning with epidemiology. The only reliable data pertain to permanent or chronic AF, which, within equivalent age groups, is markedly more prevalent among patients with CHF than in the general population [1]. This prevalence increases in parallel with the New York Heart Association (NYHA) CHF functional class and disease progression, from 10–26% among patients suffering from mild to moderate CHF (NYHA functional class II and III), to 30–50% among patients in NYHA class IV [2]. In contrast, no reliable data are available regarding the prevalence and incidence of paroxysmal AF, which should be one of the first questions addressed with the support of new implantable devices with powerful diagnostic functions. These devices, whether pacemakers or cardioverter defibrillators (ICD), are implanted at rapidly increasing rates in patients suffering from CHF without indications for treatment of bradycardia. Observational studies should be conducted with the assistance of these invaluable diagnostic tools, not only to measure the prevalence of paroxysmal AF at various stages of CHF, but also to define better its characteristics, including frequency of episodes, triggering mechanisms, circumstances surrounding its development, and spontaneous evolution. Numerous experimental and clinical observations suggest that both the triggers and electrophysiological substrates of AF in patients with CHF are different from those present in patients without structural heart disease [3]. The diagnostic functions of implanted devices offer a unique opportunity to confirm these observations, and to sharpen the focus on effective preventive therapies. Besides its epidemiology, the prognostic significance of AF in CHF remains poorly understood. Subgroup analyses of large clinical trials, such as SOLVD [4] or VAL-HeFT [5], and the recent report …