Discharge heart rate and mortality after acute myocardial infarction

We aimed to describe the determinants of discharge heart rate in acute coronary syndrome patients and assess the impact of discharge heart rate on 5-year mortality in hospital survivors.

French Registry of Acute ST-Elevation or non-ST-elevation Myocardial Infarction (FAST-MI) 2005 is a nationwide French registry that included all consecutive patients with acute myocardial infarction over 1 month in 223 institutions in 2005. Discharge heart rate was recorded in 3079 patients discharged alive; all had 5-year follow-up. Logistic regression was used to detect predictors of high heart rate at discharge. Cox's proportional hazards model was used to assess the hazard ratio for mortality at 5 years. Heart rate was categorized into 4 groups by quartiles (<60, 61-67, 68-75, >75 beats per minute). High heart rate was defined as ≥75 beats per minute. Landmark analysis was performed at 1 year.

Independent predictors of heart rate ≥75 beats per minute at discharge were female sex, ST-segment elevation myocardial infarction, diabetes, chronic obstructive pulmonary disease, bleeding/transfusion during hospitalization, left ventricular dysfunction, renal dysfunction, and prescription (type, but not dose category) of beta-blockers at discharge. Discharge heart rate was significantly related to mortality at 1 year (hazard ratio 1.13; 95% confidence interval, 1.03-1.24 per 10 beats per minute, P = .02); this was confirmed by landmark analysis, with a 39% increase (hazard ratio 1.39; 95% confidence interval 1.05-1.84) in the risk of 1-year death for discharge heart rate ≥75 beats per minute vs <75 beats per minute. This relationship was no longer significant between 2 and 5 years.

After acute myocardial infarction, patients discharged with high heart rate (≥75 beats per minute) are at higher risk of death during the first year, but not later, irrespective of beta-blocker use.