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Jun 21, 2012

Atrial Fibrillation (AF) rate control versus rhythm control


Converting and maintaining to Sinus rhythm in patient of atrial fibrillation(AF) is not for exemption of anticoagulation but to improve symptoms, quality of life, survival benefit and improve in ejection fraction. How ever this claimed benefit of sinus rhythm in AF, appears to be offset by, side effects of drugs used for maintaining sinus rhythm.

Anticoagulant therapy is advised in all patient of recurrent AF even if episodes are infrequent, and also in persistent AF on rhythm control or rate control.

Although AFFRIM trial showed no benefit of rhythm control over rate control. In post hoc analysis of AFFRIM trial, drug side effect offsetting advantages of sinus rhythm was detected. This suggest that therapies which maintain sinus rhythm without side effect profile as in AFFRIM trial are needed.

Decision of a given patient, rate versus rhythm control has be individualized. Which include nature, frequency, severity and duration of symptoms and also previous attempts of cardioversion and drug used and their side effect profile.

AFFRIM trial has shown rate control strategy to be superior in patients who are more than 65 years and asymptomatic or minimal symptomatic.

At least once Rhythm control strategy has to be attempted by transthoracic cardioversion and/or by drugs in patients with persistent AF, age less than 65 years and also in patients aged more than 65 years and symptomatic despite rate control.

AF duration more than one year and left atrial size more than 5cm, has high chance of early recurrence of AF following cardioversion, so this point has to be kept in mind before deciding rhythm control strategy.

As side effect of drugs are major deciders of outcome, so after cardioversion whether to continue antiarrhythmic drugs or not has to be decided by patient preference and also perceived risk of recurrence of AF.

Realist goal of sinus rhythm strategy is to delay the recurrence of AF by several months not by years, if recurrence is limited to one episode per year than it appropriate to continue antiarrhythmic drugs.

In patients with infrequent episodic Lone AF or AF with minimal structural heart disease “pill in pocket” strategy is advised rather than continuous therapy (to reduce side effect).

Pill in pocket strategy
This is episodic drug therapy, regimen includes class 1C drugs (Flacainide or Propafenone) and short acting beta-blockers (e.g. propranolol) or Ca channel blocker (e.g. verapamil )for rate control before cardioversion or atrial flutter preceding sinus rhythm. But in patient with severe symptoms of AF daily this prophylactic therapy is advised.