Impact of Prolonged Elevated Heart Rate on the Incidence of Major Adverse Cardiac Events in Critically Ill Patients with Underlying Chronic Heart Failure

Background Chronic Heart Failure (CHF) represents the advanced terminal stage of cardiac disease and constitutes a major public health challenge. Prolonged elevated heart rate (PeHR) has been established as a critical predictor of adverse outcomes across numerous cardiovascular conditions. However, its specific impact on major cardiac event risk in critically ill patients with pre-existing CHF requiring intensive care unit (ICU) admission remains inadequately characterized. Methods This retrospective cohort study analyzed data from the Medical Information Mart for Intensive Care (MIMIC)-IV database, version 3.0. PeHR was defined as a heart rate > 100 beats per minute recorded at least 11 time points (typically hourly) over any continuous 12-hour period during ICU hospitalization. Univariate logistic regression, multivariate logistic regression, Kaplan-Meier survival curves, and Cox proportional hazards regression analyses were employed to evaluate the independent impact of PeHR on the incidence of major cardiac events in critically ill patients with CHF, with adjustments for a wide range of demographic and clinical variables. Results A total of 9,730 critically ill patients with CHF, of whom 2,777 (28.5%) experienced PeHR. Patients in the PeHR group exhibited greater disease severity and higher rates of therapeutic interventions. After multivariable adjustment, PeHR was identified as an independent risk factor for major adverse cardiac events (MACE) (adjusted OR = 1.15, 95% CI: 1.03–1.27, P  = 0.009). PeHR significantly increased the risk of cardiac-related death (OR = 3.06) and cardiac arrest (OR = 1.54), but showed an inverse correlated with the detection rate of myocardial infarction (OR = 0.84). Trend analysis demonstrated a significant upward trend in MACE incidence with increasing heart rate intensity ( P for Trend = 0.047). Survival analysis revealed that PeHR was highly associated with poor prognosis, with a greater increase in ICU 30-day mortality risk (HR = 2.35) compared to 90-day risk (HR = 2.07). Subgroup analysis indicated that PeHR-associated risks were amplified in elderly patients, septic patients, those with acute kidney injury (AKI), and those receiving vasoactive drugs ( P  < 0.05). Conclusion PeHR is a strong independent risk factor for MACE and short-term mortality in critically ill patients with CHF. The adverse outcomes are primarily driven by fatal arrhythmias and circulatory failure rather than ischemic myocardial infarction. A significant dose-response relationship between PeHR and poor outcomes, with a stronger lethal effect during the acute phase of the disease. Aggressive identification and management of PeHR are crucial for improving outcomes in this population.