Heart rate as a risk factor in chronic heart failure (SHIFT): the association between heart rate and outcomes in a randomised placebo-controlled trial

Summary Background Raised resting heart rate is a marker of cardiovascular risk. We postulated that heart rate is also a risk factor for cardiovascular events in heart failure. In the SHIFT trial, patients with chronic heart failure were treated with the selective heart-rate-lowering agent ivabradine. We aimed to test our hypothesis by investigating the association between heart rate and events in this patient population. Methods We analysed cardiovascular outcomes in the placebo (n=3264) and ivabradine groups (n=3241) of this randomised trial, divided by quintiles of baseline heart rate in the placebo group. The primary composite endpoint was cardiovascular death or hospital admission for worsening heart failure. In the ivabradine group, heart rate achieved at 28 days was also analysed in relation to subsequent outcomes. Analysis adjusted to change in heart rate was used to study heart-rate reduction as mechanism for risk reduction by ivabradine directly. Findings In the placebo group, patients with the highest heart rates (≥87 beats per min [bpm], n=682, 286 events) were at more than two-fold higher risk for the primary composite endpoint than were patients with the lowest heart rates (70 to