Sex differences in the reclassification of acute coronary syndromes using the OMI paradigm

Occlusion Myocardial Infarction (OMI) is an emerging classification in acute coronary syndromes (ACS) that challenges the traditional STEMI/NSTEMI paradigm. It emphasizes the identification of coronary occlusion through both angiographic and biochemical criteria, potentially improving recognition of patients who require urgent revascularization. Sex-related differences in ACS have been reported, but their impact within the OMI framework remains uncertain. We explored sex-specific patterns in ACS when reclassified under the OMI framework

We conducted a retrospective one-year analysis of patients admitted with ACS to a tertiary center. All patients were reclassified according to the OMI paradigm as STEMI, NSTEMI-OMI, or NSTEMI-non-OMI, based on the presence of TIMI flow ≤2 and/or markedly elevated troponin (Troponin T >1000 ng/L or Troponin I >5000 ng/L) associated with regional wall motion abnormalities. Clinical, angiographic, and imaging data were compared between men and women within each OMI subgroup.

A total of 330 patients were included, 247 men (74.8%) and 83 women (25.2%). The distribution of OMI subgroups was similar between sexes: STEMI 58.7% vs. 61.4%, NSTEMI-OMI 15.0% vs. 18.1%, and NSTEMI-non-OMI 26.3% vs. 20.5% in men and women, respectively. Among patients initially classified as NSTEMI/UA, reclassification to OMI occurred in 36% of men and 47% of women, not reaching statistical significance.

Across OMI subgroups, peak troponin values, time to angiography, and ventricular function were assessed by sex. Median troponin values were 2508, 1349, and 175 ng/L in men, and 1654, 2146, and 270 ng/L in women, for STEMI, NSTEMI-OMI, and NSTEMI-non-OMI, respectively. Median time to angiography was 1 hour in STEMI, 10 hours in NSTEMI-OMI, and 9 hours in NSTEMI-non-OMI among men; and 1 hour, 10.5 hours, and 19 hours, respectively, among women. Left ventricular ejection fraction (LVEF) at discharge was 49%, 51%, and 57% in men, and 55%, 51%, and 60% in women across the same subgroups. At 12 months, median LVEF was 54%, 52%, and 56% in men, and 55%, 54%, and 60% in women. No statistically significant sex differences were observed.

Although some data suggest that women may experience delays of care in ACS, this was not observed in our cohort. A numerically higher proportion of NSTEMI patients were reclassified as OMI among women, although without statistical significance. The limited female representation in this study constrains the strength of these findings and underlines the importance of adequately powered, sex-balanced studies to better define the implications of OMI-based reclassification across sexes.

When ACS was reclassified according to the OMI paradigm, no significant sex differences were observed. The non-significant higher reclassification rate in women warrants further evaluation in larger, more balanced cohorts to determine whether subtle sex-related patterns exist.