Atrial fibrillation (AF) is the most frequent serious arrhythmia encountered in clinical practice. It is usually symptomatic; can reduce quality of life; commonly results in hospitalization; typically requires multiple drugs in its treatment; and can result in heart failure, embolization and its consequences, and death. Even when AF itself does not directly provoke symptoms leading to its awareness by the patient, it may still result in tachycardia-induced cardiomyopathy, embolic phenomena, and mortality.This ‘silent’ or ‘asymptomatic’ AF occasionally exists in the absence of symptomatic AF (<20% of AF patients) or may coexist with alternate periods of symptomatic AF (up to 70% of AF patients). Generally, but not consistently, periods of asymptomatic AF have slower ventricular rates than symptomatic periods, whether spontaneously or via rate-control agents).Asymptomatic AF also appears to occur relatively frequently following ablative procedures targeting the elimination of AF, speculatively due to incomplete success but alteration of sensory nerve signals.
Therapeutically, the management of AF is a challenge to even the most sophisticated practitioner, and confronting the challenges of AF can be difficult at best to exhausting on occasion. Such challenges revolve around issues of:
- rate control versus rhythm control as the primary management approach in the patient at hand;
- methods of rate control and/or rhythm control;
- definitions of therapeutic success;
- and the use of ‘ancillary’ pharmacologic agents.
In an attempt to confront these challenges, perhaps we would do best to address them one by one.
Rate Control versus Rhythm Control
Most clinicians are likely now aware that in the past half-decade or so, multiple clinical trials have been performed in a variety of AF populations to assess whether the pursuit and attainment of sinus rhythm affords a benefit to the AF patient in contrast to the benefits attained using a strategy of rate control as the primary management goal. These trials included the small Pharmacological Intervention in Atrial Fibrillation (PIAF), Strategies of Treatment of Atrial Fibrillation (STAF), and How to Treat Chronic Atrial Fibrillation (HOT-CAF─éÔÇ░) studies, the intermediatesized A Comparison of Rate Control and Rhythm Control in Patients With Recurrent Persistent Atrial Fibrillation (RACE) trial, and the large Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) trial. Although the outcome end-points in each of these trials differed somewhat, as did the nature of the population enrolled, the common themes were that:
- there was no survival benefit to a strategy of rhythm control using currently available therapeutic approaches;
- both rate control and rhythm control could improve the quality of life (QOL) of the AF patient, but not to that of the healthy normal subject; and
- when a risk-marker for embolism exists such that the AF patient requires anticoagulation with warfarin, the risk of embolism is generally not sufficiently reduced by the apparent attainment of sinus rhythm such that anticoagulation can be discontinued.