T1-mapping inversion times of the infarcted myocardium and long term cardiovascular outcomes in St-elevation myocardial infarction

Background Cardiac magnetic resonance (CMR) T1-mapping enables early characterisation of myocardial tissue following reperfused ST-elevation myocardial infarction (STEMI). Although increased T1 inversion times of the remote myocardium have been linked to adverse outcomes, the prognostic relevance of infarct zone T1 values remains uncertain. Purpose To evaluate whether higher infarcted myocardium native T1 inversion times, assessed early after STEMI, are associated with long-term major adverse cardiovascular events (MACE). Methods This was a prospective, observational substudy of a real-world STEMI registry including patients undergoing reperfusion within 12 hours of symptom onset. CMR with native T1-mapping was performed during hospitalisation. The primary endpoint was a composite of cardiovascular death, reinfarction, heart failure, or cardiogenic shock at 12 months. Patients were classified according to infarcted zone T1 values (below/above median). Statistical analyses included Kaplan–Meier estimates and Cox regression models. Results A total of 130 patients (mean age 56.7 ± 10.5 years; 93.8% male) were analysed. Median infarcted myocardium T1 inversion time was 1121 ms (IQR 1065–1192). Patients with T1 values above the median had higher left ventricular ejection fraction (48% vs 44%, p = 0.05), higher right ventricular ejection fraction (51.5% vs 45.5%, p = 0.03), and smaller end-systolic and end-diastolic volumes (p < 0.05). Microvascular obstruction (78.2% vs 91.8%, p = 0.03) and intramyocardial haemorrhage (39.1% vs 66.6%, p = 0.002) were less frequent in patients with higher T1 values. During 12-month follow-up, 27 patients (23%) experienced MACE, with no significant difference between groups (HR 0.94, 95% CI 0.44–2.01, p = 0.88). Only extensive late gadolinium enhancement remained independently associated with outcomes (HR 2.93, 95% CI 1.05–8.14). Conclusions In reperfused STEMI patients, infarcted myocardium native T1 inversion times were not directly associated with long-term adverse cardiovascular outcomes. However, lower T1 values may indicate pseudonormalisation in the presence of microvascular obstruction and intramyocardial haemorrhage, highlighting the ability of T1-mapping to capture subtle tissue changes after reperfusion. These findings demonstrate that infarct zone T1-mapping provides insight into the underlying myocardial injury and reperfusion pathology, underscoring its potential utility as an advanced imaging biomarker for mechanistic studies and translational research, and supporting further investigations in diverse STEMI populations.