Aim To determine the impact of emergent bradycardia and atrial fibrillation (AF) on cardiovascular outcomes in 19 083 patients with stable coronary artery disease (CAD) receiving ivabradine or placebo (SIGNIFY).
Methods and Results Emergent bradycardia (resting heart rate <50 bpm on 12-lead electrocardiogram) with ivabradine was reported in 3572 patients (37.4%) overall, and in 2242 (37.2%) of patients with Canadian Cardiovascular Society (CCS) class ≥2 angina. There was no difference in outcomes over the course of the study in ivabradine-treated patients with and without emergent bradycardia in the whole population (2.5% versus 2.9% per year, respectively, for primary composite endpoint of cardiovascular death or nonfatal myocardial infarction) or in the angina subgroup (2.5% versus 3.2% per year). Neither was there an increase in the rate of primary endpoint after emergent bradycardia was recorded compared with those without emergent bradycardia. There were 754 cases of emergent AF on treatment (2.2% per year ivabradine versus 1.5% per year placebo) and 469 in the patients with angina (2.2% versus 1.5% per year). While outcomes occurred more frequently in patients in whom emergent AF had been recorded, there was no treatment-placebo difference in outcomes, including stroke, and no difference in treatment effect in patients with limiting angina.
Conclusion Both in the overall population as well as in the angina subset, bradycardia was common in ivabradine-treated patients, but did not appear to impact outcomes. Emergent AF was relatively rare and did not appear to have an impact on outcomes relative to placebo.