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 mm² , 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.