Long-term prognostic importance of resting heart rate in patients with left ventricular dysfunction in connection with either heart failure or myocardial infarction: the DIAMOND study.

Background: Elevated resting heart rate is associated with increased mortality in a variety of cardiac diseases, but comparisons between different clinical settings are lacking. We investigated the long-term prognostic importance of resting heart rate in patients hospitalized with left ventricular dysfunction in connection with either heart failure (HF) or myocardial infarction (MI).

Methods: In the Danish Investigations and Arrhythmia ON Dofetilide (DIAMOND) study; patients with left ventricular dysfunction were randomized to Dofetilide (class III antiarrhythmic drug) or placebo. One part of the study enrolled 1518 patients with HF and another 1510 patients with MI. Mortality analyses were performed using multivariable adjusted Cox proportional hazard models.

Results: During 10 years of follow-up, 1076 (72%) patients with MI and 1336 (89%) patients with HF died. In multivariable adjusted models, every increment in baseline heart rate of 10 bpm was associated with an increase in mortality in both MI-patients (hazard ratio, 1.14; 95%-confidence interval (CI): 1.09-1.19; P<.0001) and HF-patients (hazard ratio, 1.10; CI: 1.06-1.15; P<.0001). The importance of resting heart rate on short-term prognosis was stronger in the MI patients compared to the HF patients (P<.0001 for interaction). There was no interaction between heart rate and beta-blockade, and inclusion of beta-blockade in the model did not change the results.

Conclusions: Resting heart rate was independently associated with increased risk of overall mortality. The prognostic importance of resting heart rate is stronger in patients with MI compared to patients with HF, especially in the short term.