Abstract 600: Concordance Between Dobutamine Echocardiography and SPECT for Detection of Myocardial Viability in Ischemic Cardiomyopathy: A Patient-by-Patient Analysis From the STICH Trial
Introduction: SPECT and dobutamine echocardiography (DE) are the most widely available methods for assessment of myocardial viability (MV) in patients with ischemic cardiomyopathy. Prior studies in which the same patients underwent both tests have shown differences in their findings, but they have all been analyzed in a segment-by-segment basis. However, in clinical practice, it is necessary to make a dichotomous determination as to whether each individual patient is likely to benefit from revascularization.
Objective: To determine how different thresholds for assessment of viability with SPECT and DE modify the rate of agreement in individual patients between these two techniques.
Methods: The Surgical Treatment of IsChemic Heart failure (STICH) trial randomized 2,136 patients with ischemic cardiomyopathy to optimal medical treatment, CABG, or surgical ventricular reconstruction. This study included the 156 patients randomized in STICH who underwent both SPECT and DE viability testing within 1 month. The rate of concordance between the two tests was analyzed using different viability thresholds (i.e., different number of viable segments per patient) for each modality.
Results: Patients had a greater number of segments considered viable by SPECT than by DE (12.8±2.9 vs 6.9±3.1, p< 0.001). When viability thresholds of 11 viable segments per patient with SPECT and 5 viable segments per patient with DE were used, the proportions of patients considered as having MV by each technique were similar (78 and 77%, respectively). The rate of concordance between both techniques was 69%. Across the spectrum of number of viable segments, a larger number of segments used as a threshold was required for SPECT compared to DE, so that both techniques would provide similar distribution of patients with and without viability. The rate of agreement between both techniques was influenced by LV size and the extent of viability (lower in patients with intermediate degrees of LV dilation and of MV), but not by LV ejection fraction.
Conclusions: When assessing MV in ischemic cardiomyopathy on a patient-by-patient basis, the concordance between SPECT and DE is determined by the thresholds used to define presence or absence of viable myocardium with each technique.