Heart rate prediction of outcome in heart failure following myocardial infarction depend on heart rhythm status an analysis from the high-risk myocardial infarction database initiative

Background: Heart rate has been reported to be associated with adverse outcome in heart failure (HF) and myocardial infarction (MI), but conflicting evidence exists regarding its impact in patients with associated atrial fibrillation (AF).

Objectives: We investigated the differential impact of heart rate on clinical outcomes according to the presence or absence of AF in patients with reduced systolic function and/or HF after MI.

Methods: We studied the association of heart rate with outcome using Cox-models in a merged dataset (n=28,771) of four randomized trials (CAPRICORN, EPHESUS, OPTIMAAL, and VALIANT).

Results: At baseline, 3736 (13%) patients had AF. We identified a significant interaction between AF and heart rate, and a decreasing effect of heart rate with time, heart rate being less associated with outcome after 1year of follow-up (both p for interaction <0.001). We report associations with outcome separately in patients with and without AF. In addition, as neutral associations with outcome after 1year were estimated after adjustment on confounding factors, only association for the first year follow-up were provided. 10-bpm increase in heart rate conferred increased risk for all-cause mortality (1.27 [1.21 to 1.33], p<0.0001), CV-mortality (1.28 [1.22 to 1.34], p<0.0001), and HF-hospitalisation (1.25 [1.19 to 1.31], p<0.0001) in patients without AF. In contrast, in patients with AF, the incremental risk for 10-bpm increase in heart rate was attenuated for all-cause (1.14 [1.06 to 1.23], p=0.0007), CV-mortality (1.12 [1.03 to 1.22], p=0.006), and HF-hospitalisation (1.16 [1.07 to 1.26], p=0.0006, p for interaction with AF <0.001 for all outcomes).

Conclusions: In patients with reduced systolic function and/or HF post-MI, higher heart rate predicts increased major cardiovascular events during the first year following MI in patients without AF. This association is markedly attenuated in subjects with AF.