Diagnostic performance of computed tomography angiography for differentiating ischemic vs nonischemic cardiomyopathy

Although the use of computed tomography angiography (CTA) is considered "appropriate" to distinguish ischemic vs nonischemic etiology in patients with cardiomyopathy under the current clinical practice guideline, the evidence to support this has not been evaluated in larger scale studies. Thus, we conducted a meta-analysis of available studies published by October 2010 to address this question.

Studies evaluating the diagnostic accuracy of CTA versus invasive coronary angiography (as the gold standard) for significant coronary artery disease (CAD) detection (ischemic cardiomyopathy) in patients with no known history of CAD with significantly depressed left ventricular function (ejection fraction; EF < 35%) were selected for the meta-analysis. Sensitivity, specificity, positive, and negative likelihood ratios were calculated on per patient and per segment basis using random effects model (DerSimonian-Laird Method) for computing summary estimates and receiver operator curve (ROC) analysis for evaluating overall diagnostic accuracy.

Six studies comprising 452 patients met the selection criteria for the meta-analysis. The pooled patient population was 62 ± 3 years old, with 29% females, 16% diabetics, and 43% with a history of hypertension. Mean EF was 32% ± 1%. The pooled summary estimate of sensitivity of CTA for diagnosis of ischemic cardiomyopathy was 98% [95% confidence interval (CI); 94% to 99%] and specificity was 97% (CI 94% to 98%), yielding a negative likelihood ratio of 0.06 (CI 0.02 to 0.13) and positive likelihood ratio of 20.85 (CI 12 to 36). There was no significant heterogeneity between studies for these estimates. The receiver operator curve analysis showed a robust discriminate diagnostic accuracy of ischemic etiology with an area under curve of 0.99 (P < .00001).

CTA appears as a clinically applicable accurate diagnostic modality to exclude ischemic etiology in patients with cardiomyopathy of undetermined cause and this further supports the appropriateness of the use of CTA to determine the cause of new onset cardiomyopathy of unknown etiology.