The Atria Are Fibrillating

Abstract

Cardiac resynchronization therapy (CRT) has become an integral treatment modality for patients with heart failure (HF), diminished left ventricular ejection fraction, and a wide QRS complex, conferring symptomatic relief, functional improvement, and survival benefit to the majority of recipients.1–4 CRT indications5 were initially restricted to patients in sinus rhythm, yet as atrial fibrillation (AF) is the most common sustained arrhythmia in patients with HF, with a prevalence that increases with more advanced HF symptoms,6 much attention has focused on expanding the CRT indications to patients with permanent AF. Article see p 566 Despite the fact that approximately a quarter of patients with HF eligible for CRT therapy have permanent AF,6 the overwhelming majority of multicenter, randomized CRT trials have only included patients in sinus rhythm.1–4 The majority of our knowledge regarding the role of CRT in patients with permanent AF is, therefore, based on nonrandomized, observational data. There are special considerations that are pertinent to CRT patients with permanent AF. First, in the absence of large, randomized, prospective trials of CRT versus no CRT in the AF population, it is not firmly established whether patients with AF derive survival, symptomatic, and structural benefits from CRT and if these benefits do occur, whether they are comparable in magnitude to those seen in patients with sinus rhythm. Second, it is not completely established how best to ensure a high burden of biventricular pacing in CRT recipients who also have AF, although the role of atrioventricular nodal ablation in this context seems to be widely accepted.7,8 From a survival perspective, there are no randomized, prospective trials examining the effect of CRT on mortality in patients with AF. Early prospective, nonrandomized, observational data,9 however, showed no difference in total mortality after …