Relationship between myocardial edema and left ventricular wall thickness in acute myocardial ischemia: A Magnetic Resonance Imaging study

Purpose: We sought to assess the relationship between left ventricular regional end-diastolic myocardial wall thickness (EDWT) and myocardial edema defined using T2-weighted Cardiovascular Magnetic Resonance (CMR) after acute myocardial ischemia and reperfusion. Methods: T2-weighted and cine CMR images for 7 dogs at baseline, during coronary occlusion (mean 33 ± 4 minutes) and after reperfusion were studied. The EDWT was measured in segments with high signal intensity (SI) on T2-weighted images, adjacent segments and remote segments according to a 16-segment model. Results: The EDWT after reperfusion in segments with high SI on T2-weighted images was significantly increased compared to baseline (6.28 ± 1.06 mm and 5.51 ± 1.40 mm, p < 0.05), whereas EDWT after the reperfusion in adjacent and remote segments did not show significant difference compared to baseline (adjacent: 6.48 ± 1.55 mm and 6.38 ± 1.26 mm, p = N.S., remote: 6.41 ± 1.11mm and 6.42 ± 1.27mm, p = N.S.). The % increase in EDWT after reperfusion from baseline in segments with high SI on T2-weighted images was higher than those in adjacent and remote segments (19 ± 30%, 1.3 ± 15% and 1.5 ± 16%, respectively, p < 0.05). Conclusions: After a brief period of ischemia and reperfusion, edema as defined by high SI on T2-weighted CMR is related to an increase in EDWT. This increase however is too small to be clinically relevant to be used for the detection of acute myocardial injury. Edema imaging is more sensitive and is an essential part of the reliable assessment of acute ischemic myocardial injury.