Rate control in atrial fibrillation, calcium channel blockers versus beta-blockers

Objective To investigate heart rate differences between non-dihydropyridine calcium channel blockers and beta-blockers in patients with non-permanent atrial fibrillation (AF). 

Methods Using data from 'A Comparison of Rate Control and Rhythm Control in Patients with Atrial Fibrillation' (AFFIRM), where patients were randomised 1:1 rate or rhythm control, we compared the effect of rate control drugs on heart rate during AF as well as during sinus rhythm. Multivariable logistic regression was used to adjust for baseline characteristics. 

Results A total of 4060 patients were enrolled in the AFFIRM trial, mean age was 70±9 years, 39% were women. Out of the total, 1112 patients were in sinus rhythm at baseline and used either non-dihydropyridine channel blockers or beta-blockers. Of them, 474 had AF during follow-up while remaining on the same rate control drugs, 218 (46%) on calcium channel blockers and 256 (54%) on beta-blockers. Mean age of calcium channel blocker patients was 70±8 years and 68±8 for beta-blocker patients (p=0.003), 42% were women. A resting heart rate <110 beats per min during AF was achieved in 92% of patients using calcium channel blockers and 92% of patients using beta-blockers (p=1.00). Bradycardia during sinus rhythm occurred in 17% of patients using calcium channel blockers vs 32% using beta-blockers (p<0.001). After adjusting for patient characteristics, calcium channel blockers were associated with a reduction in bradycardia during sinus rhythm (OR 0.41, 95% CI 0.19 to 0.90). 

Conclusion In patients with non-permanent AF, calcium channel blockers instituted for rate control were associated with less bradycardia during sinus rhythm compared with beta-blockers.