Association between coronary angiography-derived index of microcirculatory resistance and ischemic stroke in patients with ST-segment elevation myocardial infarction

Stroke is a devastating complication following ST-segment elevation myocardial infarction (STEMI). Coronary microcirculatory dysfunction (CMD) is implicated in adverse post-STEMI outcomes, but its relationship with subsequent stroke is unknown. We aimed to investigate the association of the coronary angiography-derived index of microcirculatory resistance (caIMR), a novel non-invasive tool for assessing CMD, for new-onset ischemic stroke in STEMI patients undergoing primary percutaneous coronary intervention (pPCI). This single-center, retrospective cohort study enrolled 602 consecutive STEMI patients who underwent successful pPCI between July 2020 and February 2025. The caIMR was calculated post-procedure using specialized software. The primary endpoint was new-onset ischemic stroke. Multivariable Cox proportional hazards regression and restricted cubic spline analyses were used to assess the association between caIMR and stroke risk. Over a median follow-up of 29.3 months, 38 patients (6.3%) developed a new-onset ischemic stroke. In the multivariable Cox model, caIMR was independently associated with the risk of ischemic stroke (HR: 1.044, 95% CI: 1.022–1.065, P < 0.001), along with new-onset atrial fibrillation (HR: 9.113, 95% CI: 4.587–18.107, P < 0.001). A linear dose-response relationship was observed between caIMR levels and the risk of stroke (P for non-linearity = 0.975). Reclassification analysis showed that adding caIMR improved risk classification, with an IDI of 0.0307 (95% CI: 0.0031–0.0636; P = 0.030) and an NRI of 0.3887 (95% CI: 0.3156–0.4618; P < 0.001). Elevated caIMR is independently associated with an increased risk of long-term ischemic stroke in STEMI patients after pPCI. This easily accessible metric may serve as a valuable tool for future risk stratification in this patient population.