COMBINED ASSESSMENT OF MYOCARDIAL PERFUSION AND LEFT-VENTRICULAR FUNCTION WITH EXERCISE TC-99M SESTAMIBI GATED SINGLE-PHOTON EMISSION COMPUTED-TOMOGRAPHY CAN DIFFERENTIATE BETWEEN ISCHEMIC AND NONISCHEMIC DILATED CARDIOMYOPATHY

The purpose of this study was to determine whether exercise technetium -99m sestamibi gated single-photon emission computed tomography (SPECT ) accurately distinguishes between patients with ischemic cardiomyopat hy and patients with nonischemic left ventricular systolic dysfunction . Noninvasive tests have previously failed to accurately separate pati ents with ischemic cardiomyopathy from those with nonischemic cardiomy opathy. Technetium-99m gated SPECT imaging offers advantages that have the potential to overcome the limitations of previous studies. Thirty -seven adults with a left ventricular ejection fraction less than or e qual to 35%, including 24 patients with nonischemic cardiomyopathy and 13 patients with ischemic cardiomyopathy, were prospectively evaluate d using symptom-limited metabolic exercise treadmill testing with tech netium-99m sestamibi gated SPECT imaging. Interpretation of myocardial perfusion and regional wall motion was performed, using a 17-segment model. Summed stress, rest, and reversibility perfusion defect scores were determined, and the variance of segmental wall motion scores was computed. Summed stress, rest, and reversibility perfusion defect scor es were significantly lower in nonischemic cardiomyopathy patients, co mpared with those with ischemic cardiomyopathy (summed stress defect s core: 6.9 +/- 3.8 vs 32.9 +/- 7.7, respectively, p < 0.001). Variabili ty in segmental wall motion was also significantly lower in patients w ith nonischemic cardiomyopathy compared with those with ischemic cardi omyopathy (variance: 0.3 +/- 6.3 vs 1.2 +/- 0.8, respectively, p < 0.0 01). Thus, assessment of myocardial perfusion and regional ventricular Function with exercise technetium-99m sestamibi gated SPECT imaging c an reliably distinguish between patients with ischemic cardiomyopathy and patients with nonischemic dilated cardiomyopathy. (C) 1998 by Exce rpta Medica, Inc.