Accuracy of Area at Risk Quantification by Cardiac Magnetic Resonance According to the Myocardial Infarction Territory

Abstract

Introduction and objectives: Area at risk (AAR) quantification is important to evaluate the efficacy of cardioprotective therapies. However, postinfarction AAR assessment could be influenced by the infarcted coronary territory. Our aim was to determine the accuracy of T₂-weighted short tau triple-inversion recovery (T₂W-STIR) cardiac magnetic resonance (CMR) imaging for accurate AAR quantification in anterior, lateral, and inferior myocardial infarctions.

Methods: Acute reperfused myocardial infarction was experimentally induced in 12 pigs, with 40-minute occlusion of the left anterior descending (n = 4), left circumflex (n = 4), and right coronary arteries (n = 4). Perfusion CMR was performed during selective intracoronary gadolinium injection at the coronary occlusion site (in vivo criterion standard) and, additionally, a 7-day CMR, including T₂W-STIR sequences, was performed. Finally, all animals were sacrificed and underwent postmortem Evans blue staining (classic criterion standard).

Results: The concordance between the CMR-based criterion standard and T₂W-STIR to quantify AAR was high for anterior and inferior infarctions (r = 0.73; P = .001; mean error = 0.50%; limits = -12.68%-13.68% and r = 0.87; P = .001; mean error = -1.5%; limits = -8.0%-5.8%, respectively). Conversely, the correlation for the circumflex territories was poor (r = 0.21, P = .37), showing a higher mean error and wider limits of agreement. A strong correlation between pathology and the CMR-based criterion standard was observed (r = 0.84, P < .001; mean error = 0.91%; limits = -7.55%-9.37%).

Conclusions: T₂W-STIR CMR sequences are accurate to determine the AAR for anterior and inferior infarctions; however, their accuracy for lateral infarctions is poor. These findings may have important implications for the design and interpretation of clinical trials evaluating the effectiveness of cardioprotective therapies.

Keywords: Imagen; Imaging; Infarto de miocardio; Isquemia miocárdica; Magnetic resonance imaging; Myocardial infarction; Myocardial ischemia; Resonancia magnética.