The purpose of this study was to assess the predictive value of admission heart rate (HR) for in-hospital and 1 year post-discharge mortality in a large cohort of patients hospitalized for acute myocardial infarction (MI). Data were derived from the SPRINT-2 secondary prevention study population, and included 1044 patients (aged 50-79), hospitalized in 14 coronary care units in Israel with acute MI in the years 1985-1986, before the beginning of thrombolytic therapy in acute MI. Demographic, historical and medical data were collected for each patient. All deaths during initial hospitalization and 1 year post-discharge were recorded. In-hospital mortality was 5.2% for 294 patients with HR < 70 beats/min, 9.5% for 532 patients with HR 70-89 beats/min, and 15.1% for 323 patients with HR > or = 90 beats/min (p < 0.01). One year post-discharge mortality was 4.3% for patients with HR < 70 beats/min, 8.7% for patients with HR 70-80 beats/min and 11.8% for patients with HR > or = 90 beats/min (p < 0.01). An increasing trend of mortality with higher HR was confined to patients with mild CHF (p = 0.02) and likely to patients with absent CHF (p = 0.06), but this post hoc observation requires confirmation in larger groups. The combination of high admission HR (> or = 90 beats/min) and a systolic blood pressure < 120 mmHg was a powerful predictor of in-hospital mortality. Multivariate analysis showed that admission HR was an independent risk factor for in-hospital and 1 year post-discharge mortality.(ABSTRACT TRUNCATED AT 250 WORDS)