Association of the age shock index with coronary plaque characteristics in ST‐segment elevation myocardial infarction: A 3‐vessel optical coherence tomography study

Objectives We investigated whether the age shock index (SI) was associated with coronary plaque characteristics in patients with ST‐segment elevation myocardial infarction (STEMI) using optical coherence tomography (OCT). Background The age SI is a simple clinical parameter that effectively predicts poor clinical outcomes among patients with STEMI. Methods This retrospective study evaluated 408 STEMI patients who underwent 3‐vessel OCT during emergency percutaneous coronary interventions at a single center between January 2017 and October 2018. Patients were divided into groups with low or high age SI values (<41 vs. ≥41). Plaque characteristics were compared between the two groups for both culprit lesions ( n = 408) and non‐culprit lesions ( n = 1,077). Results In culprit lesions, patients with a high age SI (≥41) were more likely to have plaque rupture (61.0% vs. 56.8%, p = .002) and thinner fibrous caps (fibrous cap thickness [FCT]: 40.0 [33.0–53.0] μm vs. 46.0 [36.0–63.8] μm, p = .021). In non‐culprit lesions, patients with a high age SI were more likely to have high‐risk plaques (29.9% vs. 17.8%, p = .018; simultaneous presence of a minimal lumen area of <3.5 mm 2 , maximum lipid arc of >180°, FCT of <75 μm, and macrophage accumulation). Plaque‐based analyses revealed that patients with a high age SI had larger lipid cores and lesser FCT. Conclusions Patients with STEMI and a high age SI had increased risks of culprit plaque rupture and high‐risk non‐culprit plaques, and vulnerable plaque features at the culprit and non‐culprit lesions. Therefore, a high age SI in patients with STEMI may indicate greater pancoronary vulnerability.