Heart rate as an independent prognostic risk factor in patients with acute myocardial infarction undergoing primary percutaneous coronary intervention

Background: It has been shown that elevated heart rate identified patients with coronary artery disease and left ventricular dysfunction at increased risk of cardiovascular outcomes.

Objective: We sought to assess the prognostic impact of heart rate at presentation in patients with ST-elevation acute myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI).

Methods and results: We collected 6-month follow-up data in 2477 consecutive patients with STEMI treated by primary PCI. Patients with atrio-ventricular block (n=64) and atrial fibrillation (n=34) were excluded from the analysis. The association of baseline heart rate with cardiovascular outcomes was analysed using Cox proportional hazard models for groups with a heart rate of 80 beats per min (bpm) or greater (n=799) versus those with a heart rate between 60 and 79 bpm (n=1192) and those with a heart rate less than 60 bpm (n=388). The variables related to mortality were: age (hazard ratio (HR) 1.072, 95% confidence interval (CI) 1.052-1.092, p<0.0001), cardiogenic shock (HR 4.622, 95% CI 2.892-7.387, p<0.0001), previous myocardial infarction (HR 1.724, 95% CI 1.036-2.869, p=0.036), peak creatine-kinase value (HR 1.227, 95% CI 1.142-1.318, p<0.0001), heart rate 80 bpm or greater (HR 2.170, 95% CI 1.414-3.332, p=0.0001), and optimal PCI result (HR 0.126, 95% CI 0.065-0.244, p=0.0001). For every increase of 5 bpm, there were increases in mortality (HR 1.321, 95% CI 1.232-1.415, p=0.0001), but not in reinfarction or in coronary revascularization rates.

Conclusion: In patients with acute myocardial infarction undergoing primary PCI, elevated heart rate (80 bpm or greater) identifies those at increased risk of death. It is unknown whether heart rate reduction will result in improved outcome in this setting of patients.