In-hospital cardiac arrest in non-ST-segment elevation myocardial infarction: characteristics and association of early intervention with risk-findings from the CCC-ACS project

Aim: In-hospital cardiac arrest (IHCA) is a catastrophic complication in patients with non-ST-segment elevation myocardial infarction (NSTEMI), who are more likely to be underrecognized and undertreated than patients with ST-segment elevation myocardial infarction. However, the epidemiology, characteristics, and factors influencing IHCA in NSTEMI patients remain poorly defined. Methods: This was a retrospective cohort study based on data from the nationwide Improving Care for Cardiovascular Disease in China-Acute Coronary Syndrome (CCC-ACS) project in China. Patients diagnosed with NSTEMI between November 2014 and December 2020 were included and stratified by IHCA occurrence. IHCA incidence among NSTEMI patients and in-hospital mortality of IHCA patients were calculated. Cox proportional hazards models were applied to identify risk and protective factors for IHCA in patients with NSTEMI. Results: Among 32,094 NSTEMI patients (29.45% female; mean age, 65.25 years), 397 (1.24%) developed IHCA. IHCA incidence decreased from 2.06% in 2014 to 0.89% in 2020, but in-hospital mortality remained high (65.74%). IHCA occurred most frequently on the day of admission (25.59%; median, 4 [1–7] days). Risk factors for IHCA included prior out-of-hospital cardiac arrest, ≥100-fold elevated TnT/TnI levels, age ≥75 years, Killip class IV, systolic blood pressure <90 mmHg, and heart rate >100 bpm at admission, history of heart failure, renal failure, ischemic stroke, and the latest glucose level >10 mmol/L. Coronary angiography before IHCA was the strongest protective factor. Conclusions: IHCA remains a fatal complication of NSTEMI, often occurring early after admission. Recognition of high-risk features, timely initiation of coronary angiography, and implementation of guideline-directed therapies may reduce IHCA occurrence.