Reassessing ACS: the role of coronary occlusion in risk stratification and management

Introduction The classification of acute coronary syndromes (ACS) traditionally distinguishes ST-elevation myocardial infarction (STEMI) from non-ST-elevation myocardial infarction (NSTEMI). However, the emerging Occlusion Myocardial Infarction (OMI) paradigm shifts the focus from ST-segment elevation to identifying coronary occlusion through more subtle electrocardiographic (ECG) changes. This approach aims to improve the identification of patients requiring urgent revascularization. OMI is defined by TIMI flow ≤2 and/or significantly elevated troponin levels (Troponin T >1000 ng/L or Troponin I >5000 ng/L) with regional wall motion abnormalities. In this study, we reclassified ACS patients using the OMI framework and analyzed their clinical characteristics and outcomes to assess its potential impact. Methods We conducted a retrospective analysis of ACS patients over one year, examining clinical, angiographic, and imaging data. Patients were stratified into STEMI, NSTEMI-OMI, and NSTEMI-NON-OMI groups. Results Among 336 ACS patients, 196 were classified as STEMI and 134 as NSTEMI/unstable angina (UA). Within the NSTEMI/UA cohort, 38.8% met OMI criteria, with 25% presenting TIMI flow ≤2. Median time to angiography was significantly shorter in STEMI patients (1 hour) than in NSTEMI-OMI patients (10.5 hours, p < 0.001) and NSTEMI-NON-OMI patients (12 hours). At discharge, median left ventricular ejection fraction (LVEF) was lower in NSTEMI-OMI patients (51%) than in NSTEMI-NON-OMI (57%, p < 0.001), with this difference persisting at 12 months (p = 0.002). Median peak troponin T levels were significantly higher in NSTEMI-OMI (1777 ng/L) than in NSTEMI-NON-OMI (217 ng/L, p < 0.001). Although STEMI patients had higher troponin levels and lower LVEF than NSTEMI-OMI patients, these differences were not statistically significant. At 12-month follow-up, clinical event rates were low across all groups, with no significant differences. Discussion: Our findings suggest that NSTEMI-OMI patients resemble STEMI patients, indicating they may benefit from a more aggressive treatment approach. However, these patients experienced delayed angiography, which may impact outcomes. The OMI paradigm presents challenges, including the lack of randomized validation and the absence of standardized ECG criteria. Furthermore, current troponin thresholds may lead to overclassification, as some patients met OMI criteria despite normal TIMI flow. The use of AI-driven tools for subtle ECG change detection could enhance early diagnosis and patient selection for urgent intervention. Conclusion Reclassifying ACS using the OMI paradigm exposes critical risk stratification and management gaps. While this approach has the potential to refine treatment strategies, further validation is necessary to optimize its clinical application and improve patient outcomes.