Association of Thrombolysis in Myocardial Infarction Myocardial Perfusion Grade with cardiovascular magnetic resonance measures of infarct architecture after primary percutaneous coronary intervention for ST-segment elevation myocardial infarction

BackgroundPrimary percutaneous coronary intervention (pPCI) routinely restores normal epicardial flow among patients with ST-segment elevation myocardial infarction (STEMI). However, impairment of myocardial perfusion frequently persists. The goal of this analysis was to determine whether impaired myocardial perfusion was associated with cardiovascular magnetic resonance–defined abnormalities in infarct architecture, including infarct size (IS), infarct surface area (ISA), infarct border zone (IBZ), and infarct complexity (IC).MethodsThirty-one patients with STEMI treated with pPCI were included in the analysis. Cardiovascular magnetic resonance was performed within 7 days of presentation and repeated at 3 months. Infarct complexity was defined as the ratio of actual ISA to an idealized smooth ISA and normalized to IS.ResultsImpaired Thrombolysis in Myocardial Infarction Myocardial Perfusion Grade (TMPG) (<3) was associated with larger ISA at baseline (78.2 ± 25.3 cm2 vs 40.3 ± 30.3 cm2, P = .02) and follow-up (58.8 ± 27.5 cm2 vs 26.3 ± 20.2 cm2, P = .03) and larger IBZ at follow-up (7.8% ± 2.7% vs 4.1% ± 3.3%, P = .02). At follow-up, ISA, when normalized to IS, was significantly higher among patients with impaired myocardial perfusion (TMPG <3) (6.9 ± 2.5 vs 5.9 ± 2.4 cm2/%, P = .03). Thrombolysis in MI myocardial perfusion grade <3 was also associated with increased IC at follow-up (52% ± 12% vs 33% ± 16%, P = .01).ConclusionsImpaired TMPG is associated with larger ISA, IBZ, and increased IC. At 3 months, TMPG remained associated with ISA and IC after adjusting for IS, suggesting that impaired TMPG after pPCI is associated with infarct architecture after healing, independent of IS.