Low-dose dobutamine gated-SPECT analysis of left ventricular segmental wall thickening in ischemic cardiomyopathy.

INTRODUCTION AND OBJECTIVES The objective of this study was to use low-dose dobutamine (LDD) gated single-photon emission computed tomography (SPECT) to evaluate segmental thickening of the left ventricle (LV) and its relationship with changes in ejection fraction (EF) and ventricular volumes in patients with ischemic cardiomyopathy. METHODS This prospective multicenter study involved 89 patients with ischemic cardiomyopathy (i.e., EF < or =40%) who underwent LDD gated-SPECT at rest. The LV was divided into 17 segments and systolic thickening was assessed in a total of 1513 segments during LDD infusion. RESULTS; A significant increase in LVEF (33.2% vs. 30.8%; P< .001) was observed during LDD infusion and occurred at the expense of a reduction in end-systolic volume (130.5 mL vs. 136.4 mL; P=.005). The increase in EF was > or =5% in 33.7% of patients, while the EF decreased by > or =5% in 5.6% of patients. With LDD infusion, both an improvement in > or =3 segments with severely decreased baseline thickening (odds ratio [OR] = 18.3; 95% confidence interval [CI], 5.3-63) and an improvement in > or =10 segments with mild-to-moderate alterations in baseline thickening (OR = 4.53; 95% CI, 1.26-16.16) were associated with a > or =5% increase in LVEF. CONCLUSIONS During the assessment of global left ventricular contractile reserve by LDD gated-SPECT, attention should be paid not only to the behavior of segments with severely decreased baseline thickening, which are generally regarded as indicating viability, but also to segments with mild-to-moderate alterations and to those in which thickening decreases.