Predicting MRI-diagnosed microvascular obstruction and its long-term impact after acute myocardial infarction.

Background: Microvascular obstruction (MVO) at cardiac magnetic resonance imaging (CMR) is a well-described risk factor for cardiac events after acute myocardial infarction (MI).

Objective: Predicting MVO using cardiac biomarkers and performing risk stratification according to extent of MVO.

Methods: We conducted a retrospective study including all patients with an acute MI and a subsequent CMR during the same hospital stay between October 2008 and August 2023. Patients were grouped according to the presence of any MVO and of relevant MVO (defined as > 1.55% of LV myocardial mass). The prediction of MVO based on peak high sensitivity cardiac troponin T (hs-cTnT) levels was analyzed. Survival according to MVO status was assessed in the entire study population.

Results: We evaluated 597 patients with CMR 3 days [interquartile range 2-4 days] after myocardial infarction. MVO was present in 163 patients (27.3%) and relevant MVO in 100 patients (16.8%). Patients with MVO had significantly higher peak hs-cTnT levels compared to those without (p < 0.001). An hs-cTnT cut-off value of > 2455.0 ng/L predicted present MVO (area under the curve (AUC) 0.824), while a cut-off value of 3975.0 ng/L predicted relevant MVO (AUC 0.837). Relevant MVO was a predictor of all-cause mortality in the entire study population (hazard ratio (HR) 3.89 (1.50-10.09)), with an even stronger association in patients with an LVEF > 35% (HR 5.91 (1.79-19.56)).

Conclusion: Higher peak hs-cTnT levels are strong predictors of MVO. Described cut-off values could serve as a screening tool. Relevant MVO is a significant predictor of all-cause mortality following acute MI, especially in patients with LVEF > 35%.