Background: Chronic total occlusion (CTO) is not uncommon among patients with coronary artery disease, but a history of prior myocardial infarction (MI) has been known to be found only in a half of patients with CTO. We investigated extent of myocardial damage using cardiac magnetic resonance imaging (CMR) and compared that with echocardiographic (Echo) as well as electrocardiographic (ECG) findings in patients with coronary artery disease having CTO

Methods: We analyzed CMR, Echo, and ECG of 96 consecutive patients (age=61+/-11 year, male gender=88%) with angiographically documented CTO obtained before PCI from Jan 2007 to Aug 2010. In addition to routine evaluations, delayed hyperenhancement (DH), which corresponds to myocardial infarction scar, was quantitatively measured using a dedicated workstation.

Results: Pathological Q wave in ECG was identified in 24% of the patients (N=23). DH was identified in all patients with Q wave, and could be found in 82% (N=73) patients without Q wave. By 2D echocardiography, the mean regional wall motion index (WMSI) was 1.253+/-0.362, and regional wall abnormalities (RWMA) were found in 53% (N=51). DH was identified in 86% (N=83) of all patients, 98% (N=50) of patients with RWMA, and still could be found in 73% (N=33) of patients without RWMA. There were significant relationships between DH volume and WMSI (r=0.535, p<0.0001) and left ventricular ejection fraction (r=0.606, p<0.0001). The cut-off threshold of DH volume that predicted RWMA was DH>=14.7 mL (AUC=0.824, sensitivity = 78%, specificity 76%, PPV 78%, NPV 76%) by ROC analysis.

Conclusions: In our CTO cohort, CMR identified the evidence of previous myocardial infarction in 86% using DH. However, Q wave in ECG and RWMA in Echo were present in 25% and 53%, respectively. Hence, the prevalence of previous myocardial infarction is shown to be much higher than previously known in patients with CTO.