Diagnostic challenges in acute coronary syndrome: reconciling the STEMI-NSTEMI and OMI-NOMI paradigms

The conventional classification of acute coronary syndromes (ACSs) into ST-elevation myocardial infarction (STEMI) and non-ST-elevation myocardial infarction (NSTEMI) relies primarily on electrocardiographic findings, particularly the presence of ST-segment elevation. However, this framework does not consistently reflect the pathophysiological factor most critical to prognosis-acute coronary artery occlusion. A substantial proportion of patients diagnosed with NSTEMI actually present with complete or near-complete coronary occlusion. Adherence to STEMI/NSTEMI-based management algorithms may therefore delay reperfusion in these individuals, potentially increasing morbidity and mortality. We evaluated limitations of the STEMI/NSTEMI model and compared it with the OMI/NOMI paradigm. We hypothesized that an occlusion-centered approach better aligns with prognosis and urgent reperfusion needs.

We conducted a retrospective single-center chort study of patients with ACS who underwent angiography or percutaneous coronary intervention (PCI). OMI was defined by either the presence of an acute culprit lesion with Thrombolysis in Myocardial Infarction (TIMI) flow grade 0-2, or a culprit lesion with TIMI 3 flow accompanied by high-sensitivity cardiac troponin I level of ≥ 5,000 ng/L.

In total, 482 patients were included: 375 men (77.8%) and 107 women (22.2%) with a mean age of 58 ± 12 years. Based on angiographic and clinical classification, 222 patients (46.1%) were STEMI - OMI, 61 (12.7%) were STEMI- NOMI, 193 (40%) were STEMI + OMI, and 6 (1.2%) were STEMI+ NOMI. The median door-to- angiography time was 39 min for STEMI + OMI, 73.5 min for STEMI+ NOMI, 540 min for STEMI - OMI, and 600 min for STEMI- NOMI. The median hospital stay was 3 days in both the STEMI + and STEMI - OMI groups, with identical in-hospital mortality rates (4.1%).

In this cohort, 46.1% of patients were classified as STEMI - OMI, experiencing markedly longer reperfusion delays than STEMI + OMI patients (median door-to- angiography time: 540 vs. 39 min). These findings suggest that the OMI-NOMI paradigm may offer greater prognostic precision and therapeutic guidance than the traditional STEMI-NSTEMI framework, particularly for patients presenting with chest pain who require emergent angiography/PCI. An occlusion-centered diagnostic approach may expedite reperfusion and improve clinical outcomes in ACS.