- New multinational study of more than 500 patients found no clear superiority of either strategy.
- The incidence of serious thromboembolic events was low, 2%, and did not differ between the arms.
- More patients in the rate control arm met protocol-specified indications for anticoagulation compared with the rhythm control arm.
There is no clinical advantage to a rhythm control vs. a rate control strategy for the management of stable postoperative atrial fibrillation (AF; Figure 1), a large open-label international study has found. The two strategies resulted in a similar number of hospital days within 60 days as well as similarly low rates of persistent AF after 60 days and rates of complications.
The two strategies differed in the time to resolution of AF, toxicities, and levels of tolerance, however. The choice of strategy should therefore be driven by patient preference, the investigators suggested.
'Patients and physicians now have the option to choose
the strategy that’s best for each individual patient.'
—Marc Gollinov, MD
Cardiothoracic Surgical Trials Network
The Cardiothoracic Surgical Trials Network (CSTN), a global collaboration of institutions that perform cardiac surgery, conducted the study after an absence of a clear winner emerged from previous studies of postoperative AF. The lack of conclusive evidence led to large variations in practice patterns for managing AF following cardiac surgery.
The incidence of postoperative AF is estimated at 33% to 50%, and is associated with morbidity, excess long-term mortality, more frequent hospitalizations, and higher cost compared with patients who undergo cardiac surgery without postoperative AF. Treating postoperative AF is estimated to add about $1 billion annually to the nation’s health care costs, said lead investigator Marc Gollinov, MD, a cardiac surgeon at Cleveland Clinic. He presented the results at a recent annual meeting of the American College of Cardiology. The data were published simultaneously in the New England Journal of Medicine.
Enrolled were 2,109 patients who were about to undergo either coronary artery bypass graft surgery (Figure 2) or valve replacement/valve repair surgery. The 523 patients with AF lasting at least 60 minutes occurring within 7 days of surgery were randomly assigned to receive either rhythm control using amiodarone with or without a rate-slowing agent or to rate control using beta blockers, calcium channel blockers, or digoxin to achieve a resting heart rate <100 bpm.
In the rhythm control arm, if AF persisted for up to 48 hours after randomization, direct current cardioversion was recommended. Patients with recurrent AF or who remained in AF >48 hours were considered for treatment with warfarin with a target international normalized ratio (INR) of 2 to 3.
Discontinuation of amiodarone was allowed for amiodarone-related adverse events, including symptomatic bradycardia and a wide QTc interval. The mean length of stay was 5.1 days in the rate control arm compared with 5.2 in the rhythm control arm (P=0.83). The proportion of patients who were free of AF at 60 days was 97.9% in the rhythm control group vs. 93.8% in the rate control group.
Non-adherence to the treatment assignment for reasons of rhythm drug toxicity or intolerance was 64.5% in patients randomized to the rhythm control strategy. Toxicity or intolerance to amiodarone often led to patients switching to rate control after hospital discharge. Twenty patients (29.9%) in the rate control arm were nonadherent because of intolerance to the drugs used for rate control.
Whereas much of the toxicity and intolerance associated with amiodarone can be avoided with rate control, resolution of AF is slower with the latter strategy, and thus more often requires anticoagulation, with its risk of bleeding, said Dr. Gillinov.
The incidence of serious thromboembolic events was low, 2%, and did not differ between the arms. This relatively low incidence of thromboembolic events came at the expense of a 3% rate of serious bleeding, which suggests a need for a closer examination of the trade-off between risks and benefits of anticoagulation in this setting, according to Dr. Gillinov. More patients in the rate control arm met protocol-specified indications for anticoagulation compared with the rhythm control arm (46.2% versus 31.8%, respectively).