Unrecognized myocardial infarction assessed by CMR is associated with hemodynamically significant stenosis at coronary angiography in patients with stable angina pectoris

Abstract

Purpose: To investigate whether unrecognised myocardial infarctions (UMI) detected by late cardiac magnetic resonance (CMR) in patients with stable coronary artery disease is associated with stenotic lesions on coronary angiography. Methods: In this multicenter study we included patients (65±8 years-of-age) scheduled for coronary angiography with symptoms of angina, but without previously known myocardial infarction (MI) or coronary intervention. CMR was performed on a clinical 1.5T scanner and consisted of delayed-enhancement images using an inversion recovery gradient echo sequence covering the entire left ventricle in the short-axis and three long-axis views. At CMR, areas of delayed contrast that were visible in at least two imaging planes were noted and localised using the AHA 17-segment model. They were categorised in four groups where and transmural in the following were labelled UMI, whereas late enhancement and were labelled no MI. CMR was followed by coronary angiography and the degree of narrowing of the diameter in each of the 19 coronary segments was categorized as 0-29% (normal), 30-49%, 50-69%, 70-99% or 100% (occlusion). If stenosis was 30% or above we determined visually, depending on the individual coronary anatomy, which of the myocardial segments in the AHA 17-segment model that downstream of the stenosis were affected by the lesion. Both CMR and coronary angiography were first evaluated separately by two independent radiologists and then in consensus, blinded for the result on the other examination. Results: 1. An analysis of the first 104 out of totally 267 included subjects showed that 26 out of the 104 had UMIs with a subendocardial component at CMR. 23 of those 26 subjects had at least one stenosis ≥70% at coronary angiography and 25 of 26 had at least one stenosis ≥30%. 2. An UMI was present in 53 out of 1768 (104*17) myocardial segments. 33 (62%) of those 53 segments were supplied by a coronary branch with ≥70% stenosis at coronary angiography. The prevalence of UMI was 1.6, 4.7 and 17.3% in the myocardial segments supplied by a coronary branch with a stenosis <70%, 70-99% and 100%, respectively (p=0.0004). Conclusions: We found a strong association between stenotic lesions above 70% at coronary angiography and UMIs at CMR, indicating that the wast majority of UMIs are of ischemic origin due to coronary atherosclerosis.