Microvascular perfusion patterns identified by contrast-enhanced CMR: prognostic implications in STEMI

Background Microvascular obstruction (MVO) after STEMI is a known predictor of adverse outcomes. On CMR, MVO is more frequently seen on early gadolinium enhancement (EGE) but can shrink or even disappear by late gadolinium enhancement (LGE), suggesting a wide spectrum of microvascular injuries. The clinical significance of these microvascular perfusion patterns (MPP) remains unclear. Purposes To evaluate the prognostic value of MPP derived from sequential EGE and LGE imaging in STEMI patients. Materials and Methods This retrospective single-center study analyzed 584 STEMI patients (mean age 60 ± 11 years; 87% male) undergoing CMR. MPP was categorized into four groups based on hypointense core on EGE (3-minute) and LGE (10-minute) image: No MVO, Reversible MVO (EGE-MVO+/LGE-MVO−), Partially Resolved MVO (LGE-MVO/EGE-MVO <30%), and Minimally Resolved MVO (≥30%). The threshold was determined as the median ratio of LGE-MVO over EGE-MVO among patients with LGE-MVO. Major adverse cardiovascular events (MACE: all-cause mortality, heart failure, reinfarction) were analyzed using Cox regression and Fine-Gray competing-risk models. Results Among participants, MPP distributed as follows: No MVO (n=157, 26.8%), Reversible MVO (n=133, 22.8%), Partially Resolved MVO (n=147, 25.2%), and Minimally Resolved MVO (n=147, 25.2%) (See Figure 1). Patients with worse microvascular perfusion had higher High-sensitivity cardiac troponin I (hs-cTNI, P<0.001) and C-reactive protein (CRP, P=0.029). Over a 3.1-year median follow-up (IQR: 1.6–4.6 years), 103 patients occurred MACE (17.6%), with escalating event rates from No MVO to Minimally Resolved MVO (See Figure 2). Patients with Reversible MVO exhibited elevated event rates (P=0.041) despite similar survival with No MVO group (log-rank P=0.07). Minimally Resolved MVO emerged as the most strong predictor of MACE, associated with a 6-fold higher MACE risk (HR: 6.11, 95% CI: 2.79–13.36; P<0.001), driven predominantly by heart failure (HR: 3.34, 95% CI: 1.02 - 10.96, P=0.047) and non-target vessel reinfarctions (HR: 5.00, 95% CI: 1.39 - 18.00, P=0.014), not all-cause mortality (P>0.05). Compared to the Canadian Cardiovascular Society (CCS) classification for myocardial infarction1, MPP exhibited a net reclassification improvement of 22.0% (95% CI: 4.9–33.8%; P<0.001) and provided incremental prognostic value beyond CCS stages. Conclusion MPP was associated with prognosis and demonstrated superior risk stratification compared to the Static CCS stages in STEMI, highlighting the clinical utility of MVO perfusion dynamics.