Do Calcium Channel Blockers Lower the Risk of Bradycardia in Atrial Fibrillation?

In patients with non-permanent atrial fibrillation (AF), non-dihydropyridine calcium channel blockers used for rate control were associated with significantly less bradycardia during sinus rhythm compared with beta-blockers. Both medications were equally effective in controlling heart rate during AF.

AF is a common cardiac arrhythmia, and rate control is a key therapeutic strategy for managing its symptoms and complications. Two major medications for rate control are non-dihydropyridine calcium channel blockers and beta-blockers. However, there is limited evidence comparing their effectiveness in heart rate control and the incidence of bradycardia during sinus rhythm. This study aims to fill that gap by investigating the differences in heart rate management between these two medications in patients with non-permanent AF.

For their study, Koldenhof and colleagues used data from the AFFIRM (A Comparison of Rate Control and Rhythm Control in Patients with Atrial Fibrillation) trial, in which patients were randomized to rate or rhythm control. Of the 4060 patients in the trial, the analysis focused on 1112 patients who were in sinus rhythm at baseline and treated with either non-dihydropyridine calcium channel blockers or beta-blockers for rate control. During follow-up, 474 of these patients had episodes of AF while remaining on the same rate control medication. The researchers used multivariable logistic regression to adjust for baseline characteristics and compared the impact of these medications on heart rate control during AF and sinus rhythm.

Among the 474 patients with AF during follow-up, 218 (46%) were treated with calcium channel blockers, and 256 (54%) received beta-blockers. Regarding heart rate control, a resting heart rate of <110 beats per minute (bpm) during AF was achieved in 92% of patients on calcium channel blockers and 92% on beta-blockers (p = 1.00), indicating no significant difference in their efficacy for rate control during AF. However, a marked difference was observed in the occurrence of bradycardia during sinus rhythm. Bradycardia occurred in 17% of patients on calcium channel blockers compared to 32% of those on beta-blockers (p < .001). After adjusting for baseline characteristics, calcium channel blockers were associated with a significant reduction in bradycardia during sinus rhythm (odds ratio, 0.41, 95% CI 0.19 to 0.90).

A key limitation of the study is its retrospective design, using data from the AFFIRM trial, which may introduce selection bias. Additionally, the analysis only included patients who remained on the same rate control medications during follow-up, which might not reflect all clinical scenarios. The study also did not explore long-term outcomes such as mortality or quality of life differences between the two medication classes.

"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,” the study authors concluded.

Reference

Koldenhof T, Van Gelder IC, Crijns HJ, et al. Rate control in atrial fibrillation, calcium channel blockers versus beta blockers. Heart. 2023;109(23):1759-1764. doi:10.1136/heartjnl-2023-322635.