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

Background: The clinical manifestations in patients with ischemic cardiomyo pathy are often indistinguishable from those in patients with primary dilat ed cardiomyopathy (DCM). Clinicians often base work-up of patients with hea rt failure on echocardiographic wall motion abnormalities; however misclass ification 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 betwee n ischemic and nonischemic cardiomyopathy. Methods: The accuracy of EBT and echocardiography was compared in ill patie nts undergoing coronary angiography for the evaluation of heart failure. Th e presence of coronary calcification (CC) by EBT or segmental wall motion a bnormalities by echocardiography was used as evidence of coronary-induced c ardiomyopathy. Results: Of 63 patients, 61 (97%) with obstructive coronary artery disease had CC by EBT. This sensitivity was significantly higher compared with 43 o f 63 patients (68%) with segmental wall motion abnormalities by echocardiog raphy (p < 0.001). Of 48 patients without obstructive coronary artery disea se 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 overal l 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 echocard iography to distinguish ischemic from nonischemic cardiomyopathy. This moda lity may prove to be an important diagnostic tool when the etiology of the cardiomyopathy is not clinically evident.