Usefulness of electron beam computed tomography scanning for distinguishing ischemic from nonischemic cardiomyopathy

Objectives. This study was undertaken to evaluate the ability of electron beam computed tomography (EBCT) to distinguish ischemic from nonischemic causes of cardiomyopathy by evaluating heart failure patients for coronary calcification (CC), Background. The etiology of heart failure, whether coronary-induced or nonischemic, may be difficult to discern clinically. Differentiation of ischemic from nonischemic etiology is clinically important for both therapeutic and prognostic implications, With its ability to noninvasively discern and quantitate coronary artery calcification, EBCT correlates well with angiographic stenosis and thus may be useful in distinguishing ischemic and nonischemic cardiomyopathies, Methods. One hundred and twenty-five patients with cardiomyopathy (ejection fraction <0.40) and known coronary anatomy underwent EBCT coronary scanning to evaluate for CCs within 3 months of coronary angiography, Results. Of the 72 patients who were found to have ischemic cardiomyopathy, 71 patients had CC by EBCT (sensitivity 99%, p < 0.001), mean score 798 +/- 899, In comparison, among the 53 patients without significant coronary artery disease (CAD) (nonischemic cardiomyopathy), the mean score was significantly lower (17 +/- 51; p < 0.0001), and 44 patients had a CC score of 0 (no CC present). The specificity of EBCT to exclude CAD in patients with cardiomyopathy was 83%, using a threshold CC score of 0, and 92% for scores <80 (p < 0.001). Overall accuracy for determining the etiology of cardiomyopathy (differentiating ischemic from nonischemic) was 92% for this technique. Conclusions. This prospective, blinded study indicates that EBCT detected CC accurately and can noninvasively distinguish between cardiomyopathy because of CAD and nonischemic causes of left ventricular dysfunction, (C) 1998 by the American College of Cardiology.