ETD

• cardiac magnetic resonance imaging
• scar dispersion score
• ST-segment elevation myocardial infarction
• sudden cardiac death
• thrombectomy

Background - The role of adjunctive thrombectomy during primary percutaneous coronary intervention (pPCI) for ST-segment elevation myocardial infarction (STEMI) remains controversial. While early trials suggested improved reperfusion, large multicenter studies failed to demonstrate survival benefit, often limited by short follow-up. Moreover, conventional risk stratification after STEMI relies mainly on left ventricular ejection fraction (LVEF), a modest discriminator of arrhythmic risk. Scar heterogeneity, a known arrhythmogenic substrate, may provide incremental prognostic value when assessed by cardiac magnetic resonance (CMR).
Purpose - This study sought to determine the long-term clinical impact of thrombectomy in thrombus-rich STEMI and to evaluate whether myocardial scar heterogeneity, quantified by a novel CMR-derived Scar Dispersion Score (SDS), predicts adverse outcomes.
Methods - We performed a 15-year follow-up of the MUSTELA randomized controlled trial, which enrolled 208 STEMI patients with angiographically confirmed high thrombus burden randomized to pPCI with or without thrombectomy. Clinical outcomes were retrospectively assessed in 109 patients (mean follow-up 15.8 ± 0.9 years). Endpoints included cardiovascular death, sudden death, and a composite of adverse cardiovascular events. Infarct characteristics were assessed by CMR at 3 months, and scar heterogeneity was quantified by SDS from late gadolinium enhancement images. Associations between treatment, SDS, and outcomes were evaluated using logistic regression and Kaplan–Meier survival analysis.
Results - During long-term follow-up, 81 patients (74.3%) reached the composite endpoint, 73 (67.0%) experienced cardiovascular death, and 38 (34.9%) suffered sudden death. Thrombectomy showed no survival benefit and was independently associated with a higher incidence of sudden death (HR 2.50, 95% CI 1.04–5.99). Median SDS was significantly greater in thrombectomy patients (6.0 [IQR 5–7]) compared with controls (3.0 [IQR 2–4], p<0.001). High SDS (≥4) was a powerful independent predictor of cardiovascular death (HR 2.34, 95% CI 1.22–4.45) and sudden death (HR 7.45, 95% CI 1.78–31.10), irrespective of LVEF or infarct size. In contrast, no association was found with all-cause mortality.
Conclusions - In this extended 15-year follow-up of the MUSTELA trial, thrombectomy during pPCI for STEMI with thrombus-rich lesions did not confer long-term clinical benefit and was linked to higher sudden death risk, potentially through enhanced scar heterogeneity. The Scar Dispersion Score (SDS) emerged as a robust, independent predictor of cardiovascular mortality and sudden death. An SDS threshold ≥4 identified patients at particularly high arrhythmic risk, suggesting that scar heterogeneity assessment by CMR may refine post-STEMI risk stratification and inform prophylactic ICD indication beyond traditional LVEF-based criteria.