Prognosis and risk stratification in first-presentation myocardial infarction with nonobstructive coronary arteries...

To evaluate the prognostic value of stress cardiac MRI in myocardial infarction with nonobstructive coronary arteries (MINOCA), and to investigate its efficacy in risk stratification.

A total of 279 MINOCA patients undergoing stress cardiac MRI were retrospectively enrolled. Patients were classified into 4 subgroups according to the cardiac MRI phenotype: (1) presence of late gadolinium enhancement (LGE) and inducible ischemia+ (n = 95); (2) LGE+/inducible ischemia- (n = 72); (3) LGE-/inducible ischemia+ (n = 69); and (4) LGE-/inducible ischemia- (n = 43). The primary outcome was major adverse cardiovascular events (MACE).

Over a median follow-up of 41 months, MACE occurred in 11.5% of patients. Those who developed MACE showed significantly reduced cardiac function (left ventricular ejection fraction (LVEF): 38.6 [35.2; 51.6] vs 54.5 [48.7; 61.6], p < 0.001), severe microvascular dysfunction (myocardial perfusion reserve (MPR): 1.5 [1.4; 1.7] vs 1.9 [1.8; 2.6], p < 0.001), and extensive myocardial damage (LGE: 9.6 [7.7; 25.6] vs 2.4 [0.0; 6.2], p < 0.001). Multivariate Cox regression showed that LGE (HR: 1.108, 95% CI: 1.047-1.172, p < 0.001) and MPR (HR: 0.062, 95% CI: 0.007-0.524, p = 0.011) were independently associated with MACE. Kaplan-Meier analysis indicated that patients with LGE ≥ 8.39 and MPR < 1.75 had a significantly higher MACE risk (p < 0.001).

In MINOCA patients, LGE and MPR independently predict MACE risk. Particularly, MPR offers incremental prognostic value by further stratifying patients with limited LGE.

MINOCA is a clinically important and heterogeneous entity, often associated with adverse long-term outcomes. Stress cardiac MRI parameters, LGE and MPR, can predict the prognosis of patients with MINOCA, facilitating risk stratification and guiding subsequent management decisions.

Stratifying MINOCA patients into subgroups based on cardiac MRI tissue and functional characteristics enables refined risk stratification. In MINOCA patients with limited LGE, impaired MPR is associated with a higher incidence of MACE. Microvascular dysfunction may be recognized as one of the potential mechanisms contributing to MINOCA and is associated with adverse cardiovascular outcomes.