Relationship between CMR-derived parameters of ischemia/reperfusion injury and the timing of CMR after reperfused ST-segment elevation myocardial infarction

BACKGROUND: To investigate the influence of cardiovascular magnetic resonance (CMR) timing after reperfusion on CMR-derived parameters of ischemia/reperfusion (I/R) injury in patients with ST-segment elevation myocardial infarction (STEMI). METHODS: The study included 163 reperfused STEMI patients undergoing CMR during the index hospitalization. Patients were divided according to the time between revascularization and CMR (T(revasc-CMR): Tertile-1 ≤ 43; 43 < Tertile-2 ≤ 93; Tertile-3 > 93 h). T2-mapping derived area-at-risk (AAR) and intramyocardial-hemorrhage (IMH), and late gadolinium enhancement (LGE)-derived infarct size (IS) and microvascular obstruction (MVO) were quantified. T1-mapping was performed before and > 15 min after Gd-based contrast-agent administration yielding extracellular volume (ECV) of infarct. RESULTS: Main factors influencing I/R injury were homogenously balanced across T(revasc-CMR) tertiles. T2 values of infarct and remote regions increased with increasing T(revasc-CMR) tertiles (infarct: 60.0 ± 4.9 vs 63.5 ± 5.6 vs 64.8 ± 7.5 ms; P < 0.001; remote: 44.3 ± 2.8 vs 46.1 ± 2.8 vs ± 46.1 ± 3.0; P = 0.001). However, T2 value of infarct largely and significantly exceeded that of remote myocardium in each tertile yielding comparable T2-mapping-derived AAR extent throughout T(revasc-CMR) tertiles (17 ± 9% vs 19 ± 9% vs 18 ± 8% of LV, respectively, P = 0.385). Similarly, T2-mapping-based IMH detection and quantification were independent of T(revasc-CMR). LGE-derived IS and MVO were not influenced by T(revasc-CMR) (IS: 12 ± 9% vs 12 ± 9% vs 14 ± 9% of LV, respectively, P = 0.646). In 68 patients without MVO, T1-mapping based ECV of infarct region was comparable across T(revasc-CMR) tertiles (P = 0.470). CONCLUSION: In STEMI patients, T2 values of infarct and remote myocardium increase with increasing CMR time after revascularization. However, these changes do not give rise to substantial variation of T2-mapping-derived AAR size nor of other CMR-based parameters of I/R. TRIAL REGISTRATION: ISRCTN03522116. Registered 30.4.2018 (retrospectively registered).