Anatomy Meets Biology: The Synergistic Prognostic Power of Residual SYNTAX Score and OCT in STEMI

<title>Abstract</title> <p> <bold>Background:</bold> ST-elevation myocardial infarction (STEMI) remains a major cause of global morbidity and mortality. While percutaneous coronary intervention (PCI) is the primary reperfusion strategy, residual coronary disease and plaque vulnerability significantly affect outcomes. The residual SYNTAX score (rSS) quantifies incomplete revascularization, while optical coherence tomography (OCT) provides detailed plaque assessment, particularly identifying thin-cap fibroatheroma (TCFA), a marker of plaque vulnerability. This pilot study explores the descriptive characteristics and short-term outcomes associated with combining rSS and OCT-derived TCFA in a highly selected STEMI cohort. <bold>Materials &amp; Methods:</bold> This retrospective observational study included 30 STEMI patients who underwent PCI and OCT evaluation at a tertiary care center. Baseline clinical, angiographic, and OCT data were analyzed. Patients were stratified into four groups based on the presence of TCFA and rSS (≤4 vs. &gt;4). The primary endpoint was major adverse cardiac events (MACE), a composite of all-cause death, recurrent myocardial infarction, target lesion revascularization, heart failure, and ischemic stroke at a 3-month follow-up. <bold>Results:</bold> The cohort (N=30) had a mean age of 54.5 ± 10.1 years, was 83.3% male, and 49% presented with multivessel disease. TCFA was observed in 39% of culprit lesions. Overall MACE incidence at 3 months was exceptionally high at 30% (9 out of 30 patients), indicating a high-risk, skewed population. High rSS (&gt;4) and the presence of TCFA independently predicted higher event rates and the worst outcomes (45.5% MACE), whereas those with complete revascularization and no TCFA had the lowest event rates (0%). <bold>Conclusion:</bold> Incomplete revascularization and TCFA independently predict adverse outcomes post-PCI in STEMI. Their combination identifies a high-risk subgroup, supporting the integrated use of rSS and OCT for enhanced risk stratification. </p>