Further Validation of a Novel Acute Myocardial Infarction Risk Stratification (nARS) System for Patients with Acute Myocardial Infarction

Recently, we developed a novel acute myocardial infarction (AMI) risk stratification system (nARS), which stratifies AMI patients into low- (L), intermediate- (I), and high- (H) risk groups. We have shown that the nARS shortened the length of intensive care unit (ICU) stay as well as that of hospitalization. However, the incidence of AMI-related adverse outcomes has not been fully investigated. The purpose of this study was to investigate the incidence of severe complications requiring ICU care among the 3 risk groups stratified by nARS. We retrospectively reviewed AMI patients between October 2016 and December 2018. A total of 592 patients were divided into the L- (n = 285), I- (n = 124), and H- (n = 183) risk groups. The primary endpoint was in-hospital complications requiring ICU care defined as death/cardiopulmonary arrest, shock, stroke, atrioventricular block, and respiratory failure. Among 592 patients, 239 (40.4%) developed at least 1 complication requiring ICU care, but only 28 (11.7%) developed complications in general wards. Complications requiring ICU care were most frequently observed in the H-risk group (68.9%), followed by the I-risk group (50.8%), and least in the L-risk group (17.5%) (P < 0.001). Complications requiring ICU care that occurred in the general wards were more frequently observed in the H-risk group (8.7%) compared to the I-risk (3.2%) and L-risk (2.8%) groups (P = 0.009). In conclusion, complications requiring ICU care rarely happened in the general wards, and were less in the I- and L-risk groups than in the H-risk group. These results validated the nARS, and might support the widespread use of nARS.