Prognostic value of admission respiratory rate in patients with acute myocardial infarction

BACKGROUND: Respiratory rate (RR) is one important vital sign that is often neglected in patients with acute myocardial infarction (AMI). The present study aimed to evaluate the impact of admission RR on the prognosis in patients with AMI. METHODS: This study included 5631 AMI patients from Medical Information Mart for Intensive Care IV (MIMIC-IV) and 1323 patients from The First Affiliated Hospital of Chongqing Medical University (validation cohort). The primary endpoint was 30-day all-cause mortality. Patients were divided into increased RR group (RR > 20 breaths/min) and normal RR group (RR ≤ 20 breaths/min) based on admission RR. RESULTS: In the MIMIC-IV cohort, the median age was 70 years and 3503 (62.2%) patients were male. Compared to patients with normal RR, patients with admission RR > 20 breaths/min had significantly increased risk of 30-day all-cause mortality (14.2% vs. 27.5%, p < 0.001). After multivariate adjustment, admission RR > 20 breaths/min was independently associated with increased risk of 30-day all-cause mortality (HR 1.715; 95%CI 1.507-1.952, p < 0.001). The findings from MIMIC-IV were validated in the data from The First Affiliated Hospital of Chongqing Medical University and the results were consistent. CONCLUSION: RR is not only a vital sign but also a simple and practical indicator for predicting the prognosis of patients with AMI. Increased RR upon admission independently predicted a higher risk of poor outcomes, making it a valuable tool for early risk stratification and guiding timely interventions.