Admission heart rate and in-hospital mortality in acute myocardial infarction: a contemporary analysis of the MIMIC-III cohort
Admission heart rate (HR) in patients with acute myocardial infarction (AMI) exhibits a U-shaped association with in-hospital mortality, with both bradycardia (<60 bpm) and tachycardia (≥100 bpm) conferring significantly increased risk compared to the reference range (60–99 bpm).
After multivariable adjustment—including for age, sex, Killip class, systolic blood pressure, reperfusion therapy, comorbidities, and initial laboratory values—HR <60 bpm was associated with a 58% higher odds (aOR 1.58, 95% CI 1.02–2.45) and HR ≥100 bpm with a 145% higher odds (aOR 2.45, 95% CI 1.56–3.85) of in-hospital death.
The U-shaped HR–mortality relationship remained robust even after sensitivity analyses accounting for early mortality (<24 h).
This relationship is more pronounced in STEMI patients than in those with NSTE-ACS, with the steepest rise in mortality observed in STEMI patients presenting with tachycardia, and a somewhat greater impact of bradycardia in NSTE-ACS.
The optimal HR nadir for lowest in-hospital mortality differed by AMI subtype (≈78 bpm in STEMI and ≈72 bpm in NSTE-ACS), indicating a need for subtype-specific monitoring and intervention thresholds.
No significant effect modification by age, sex, hypertension, or early β-blocker use was observed, suggesting that the prognostic value of admission HR is consistent across these subpopulations.
Admission HR reflects integrated physiological responses, including autonomic tone, hemodynamic stress, and underlying conduction system disturbances, and thus serves as a rapid and practical risk stratification tool at the bedside.
Clinical implication: Patients presenting with admission HR outside the 60–99 bpm range MAY warrant prompt hemodynamic stabilization and closer monitoring, and prospective studies are needed to determine whether targeted HR normalization improves short-term outcomes in AMI.