Prognostic Value of Angiography-derived Index of Microcirculatory Resistance in Patients with diabetes and ST-Segment Elevation Myocardial Infarction.

Background: The occurrence of coronary microvascular dysfunction (CMD) after primary PCI in DM patients with STEMI and its impact on prognosis remains elusive.

Methods: This single-center retrospective observational study included 293 patients diagnosed with DM and STEMI. The caIMR was calculated using the measurement software FlashAngio, while cardiac magnetic resonance parameters were quantified using the post-processing software Cvi42. CMD was defined as caIMR ≥ 25 U. The primary endpoint was MACE, defined as all-cause mortality, non-fatal myocardial infarction, ischemia-driven revascularization, and heart failure.

Results: MACE occurred in 86 patients (29.4%) during a median follow-up of 31 months. A significant correlation was identified between caIMR and both microvascular obstruction (MVO) (R = 0.61, P < 0.001) and infarct size (IS) (R = 0.39, P < 0.001). Furthermore, caIMR ≥ 25 was identified as an independent risk factor for MACE (HR, 2.99; 95% CI, 1.78-5.03; P < 0.001). Additionally, the integration of caIMR into risk modeling significantly improved MACE prediction (Net reclassification improvement 0.264, P<0.001; Integrated discrimination improvement 0.060, P<0.001). Lastly, the Kaplan-Meier survival curves displayed that patients with caIMR ≥ 25 were at a higher risk of MACE (log-rank P < 0.001).

Conclusion: The caIMR demonstrated a satisfactory correlation with CMR-determined MVO and IS in DM patients with STEMI. Elevated caIMR was independently linked to a higher risk of MACE in diabetic STEMI patients post-PCI, serving as an effective predictor for MACE.