Aims: To evaluate the relationship between presenting heart rate (HR) and in-hospital events in patients with non-ST-segment elevation acute coronary syndromes (NSTE-ACS).
Methods and results: We evaluated 139 194 patients with NSTE-ACS in the CRUSADE quality improvement initiative. The presenting HR was summarized as 10 beat increments. Patients with systolic BP < 90 mm Hg (4030 patients) were excluded to avoid the confounding effect of cardiogenic shock. An adjusted odds ratio (OR) was calculated using a reference OR = 1 for HR of 60-69 b.p.m. after controlling for baseline variables. Primary outcome was a composite of in-hospital events all-cause mortality, non-fatal re-infarction, and stroke. Secondary outcomes were each of these considered separately. From the cohort of 135 164 patients, 8819 (6.52%) patients had a primary outcome (death/re-infarction or stroke) of which 5271 (3.90%) patients died, 3578 (2.65%) patients had re-infarction, and 1038 (0.77%) patients had a stroke during hospitalization. The relationship between presenting HR and primary outcome, all-cause mortality, and stroke followed a 'J-shaped' curve with an increased event rate at very low and high HR even after controlling for baseline variables. However, there was no relationship between presenting HR and risk of re-infarction.
Conclusion: In contrast to patients with stable CAD, in the acute setting, the relationship between presenting HR and in-hospital cardiovascular outcomes has a 'J-shaped' curve (higher event rates at very low and high HRs). These associations should be considered in ACS prognostic models.