Stress variables add differential diagnostic information between ischemic and nonischemic cardiomyopathy over myocardial perfusion SPECT imaging

Abstract

Noninvasive differentiation between ischemic cardiomyopathy (ICM) and nonischemic (NICM) cardiomyopathy is frequently difficult. The aim of this study was to analyze the value of stress test and stress-rest gated single-photon emission computed tomography (SPECT) criteria to differentiate between ICM and NICM. Data pertaining to 145 consecutive patients (mean age: 63±11 years, 24 women) assessed by means of stress-rest gated SPECT with Tc-tetrofosmin, with left ventricular ejection fraction less than or equal to 40% (107 patients with ICM and 38 with NICM according to coronary angiography) and known coronary anatomy, were analyzed. Multivariate analyses of gated SPECT variables identified a summed stress score greater than 21 [odds ratio (OR) 7.67, 95% confidence interval (CI): 2.85-20.58)] and divergent pattern (OR 6.84, 95% CI: 1.83-25.5) as predictors of ICM, and analysis of exercise test variables disclosed metabolic equivalents less than or equal to 7.3 (OR 10.75, 95% CI: 3.64-31.81) and ST depression of at least 1 mm (OR 6.97, 95% CI: 1.42-34.3) as independent predictors of ICM. The exercise test variables had a significant additional predictive value of ICM over gated SPECT variables (P<0.001). Estimated functional capacity and ST depression improve the diagnostic value of stress-rest SPECT to differentiate between ICM and NICM.