Comparison of echocardiography and electron beam tomography in differentiating the etiology of heart failure.

BACKGROUND: The clinical manifestations in patients with ischemic cardiomyopathy are often indistinguishable from those in patients with primary dilated cardiomyopathy (DCM). Clinicians often base work-up of patients with heart failure on echocardiographic wall motion abnormalities; however misclassification can lead to unnecessary coronary angiography. HYPOTHESIS: The study was undertaken to evaluate the diagnostic ability of echocardiography and electron beam tomography (EBT) to differentiate between ischemic and nonischemic cardiomyopathy. METHODS: The accuracy of EBT and echocardiography was compared in 111 patients undergoing coronary angiography for the evaluation of heart failure. The presence of coronary calcification (CC) by EBT or segmental wall motion abnormalities by echocardiography was used as evidence of coronary-induced cardiomyopathy. RESULTS: Of 63 patients, 61 (97%) with obstructive coronary artery disease had CC by EBT. This sensitivity was significantly higher compared with 43 of 63 patients (68%) with segmental wall motion abnormalities by echocardiography (p < 0.001). Of 48 patients without obstructive coronary artery disease by angiography, 39 (81%) had no CC by EBT and 35 (73%) had no segmental wall motion (global hypokinesis) by echocardiography (p = 0.33). The overall accuracy of EBT to differentiate ischemic from nonischemic cardiomyopathy was 90%, significantly higher than echocardiography (70%, p < 0.001). CONCLUSION: This double-blind study demonstrates that the presence of CC by EBT is superior to that of segmental wall motion abnormalities by echocardiography to distinguish ischemic from nonischemic cardiomyopathy. This modality may prove to be an important diagnostic tool when the etiology of the cardiomyopathy is not clinically evident.

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.