Rate and rhythm control similar in atrial fibrillation after cardiac surgery

1. In this randomized controlled trial, there was no difference in total length of hospital stay after elective cardiac surgery in patients with postoperative atrial fibrillation randomized to either rhythm or rate control.

2. The secondary outcomes of death and adverse events also did not show any significant difference.

Evidence Rating Level: 1 (Excellent)

Study Rundown: Atrial fibrillation after cardiac surgery is associated with mortality and morbidity. However, it is unclear whether rate or rhythm control after such surgery is the better initial management strategy. This randomized controlled trial compared rate and rhythm control in stable patients with new post-operative atrial fibrillation on the total length of hospital stay within 60 days after randomization.

Postoperative atrial fibrillation occurred in 33% of patients undergoing cardiac surgery. The mean number of days in hospital was not significantly different between the rate-control vs. rhythm-control groups. There was also no significant difference in rates of death or overall adverse outcomes between the two medical management styles. Approximately 25% of patients could not adhere to their assigned treatment strategy. The main reasons for switching treatment groups were: amiodarone side effects in the rhythm-control group, or drug ineffectiveness in the rate-control group. There was also a non-significant difference in proportion of patients free from atrial fibrillation from discharge or 60 days. Limitations include the use of a surrogate outcome for mortality or another clinically relevant outcome. Also there was a high rate of treatment discontinuation but the effects of these were minimized in the secondary intention-to-treat analysis.

Click to read the study, published today in NEJM

Relevant Reading: A Comparison of Rate Control and Rhythm Control in Patients with Atrial Fibrillation (AFFIRM)

In-Depth [randomized controlled trial]: This randomized controlled trial was conducted from May 2014 to 2015 at over 20 sites across the USA and Canada. Patients who were hemodynamically stable undergoing elective cardiac surgery with no history of atrial fibrillation were enrolled. Those who had post-operative atrial fibrillation were randomized to rhythm-control (amiodarone with or without a rate control agent) or rate control (HR controlled to <100 beats per minute). If patients in the rate control group did not respond to the strategy of rate control they were switched to rhythm control if this could alleviate symptoms or improve their hemodynamic status. If participants in the rhythm control group could not attain control, cardioversion was recommended. The primary endpoint was the total number of days in the hospital (including emergency department visits within 60 days after randomization). Secondary outcomes included length of index hospital stay, need for readmission, rates of death and adverse events.

Of all patients undergoing elective cardiac surgery, 33% (N=695) had postoperative atrial fibrillation. Of these, 595 underwent randomization. The total numbers of hospital days were similar across the rate and rhythm-control groups (median 5.1 vs. 5.0 days respectively; p= 0.76). There was also no significant different in death (p=0.64) or adverse events (p=0.61). However, up to 25% of patients in each group deviated from their assigned treatment strategy. Reasons for deviation included preference of patient or provider (20% vs. 35%, rate vs. rhythm control respectively), ineffectiveness of HR drug (51% of rate control patients), or side effects of the amiodarone (65% in the rhythm control patients).

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