Heart rate and prognosis in acute coronary syndromes

Resting heart rate (RHR) is inversely correlated with the average life span of living beings. In coronary patients, increased RHR has been associated with rapid progression of atherosclerosis. The aim of this study was to compare in-hospital and long-term outcome of acute coronary syndromes according to patients' RHR.

We prospectively studied 1720 consecutive patients, divided into two groups according to RHR at admission: group A--RHR > or =82 bpm (n=543), and group B--RHR < 82 bpm (n=1177). Epidemiological, clinical, laboratory and therapeutic data were analyzed for both groups. Appropriate statistical tests and multivariate analysis were used to identify independent predictors of in-hospital and one-year mortality.

Group A included more women (35.9% vs. 27.0%, p < 0.001), older (68.36 +/- 12.74 vs. 66.39 +/- 12.43 years, p = 0.002), and diabetic patients (30.9% vs. 25.1%, p = 0.014) and non-smokers (85.8% vs. 81.4%, p = 0.024). They were admitted more often with ST-segment elevation myocardial infarction (31.5% vs. 21.5%, p < 0.001), presented higher Killip class at admission and had worse left ventricular ejection fraction (47.99 +/- 11.87% vs. 52.45 +/- 10.32%, p < 0.001). Peak myocardial markers, creatinine and blood glucose at admission were significantly higher in this group. Discharge medication was not statistically different. In-hospital mortality (7.7% vs. 3.3%, p < 0.001) and morbidity (10.4% vs. 4.9%, p < 0.001) and one-year mortality (21.3% vs. 9.6%, p < 0.001) and morbidity (43.9% vs. 36.4%, p = 0.009) were higher in the group with RHR > or =82 bpm. The independent predictors of in-hospital mortality were age > or =70.5 years (p = 0.001), RHR > or =82 bpm at admission (p = 0.035) and previous type 2 diabetes (p = 0.004). Age > or =69.5 years (p < 0.001) and RHR > or =82 bpm (p = 0.008) were also independent predictors of one-year mortality, together with Killip class >I (p < 0.001) and ejection fraction < or =49.5% (p < 0.001).

In our population of acute coronary syndrome patients, RHR > or =82 bpm was associated with worse short- and long-term outcome.