Dipyridamole Tl-201 SPECT in Hypertrophic Cardiomyopathy with Asymmetric Septal Hypertrophy:Characteristics of Perfusion Abnormality and Correlation with Clinical Parameters

Abstract

Background and Objectives:Exercise myocardial perfusion scans in patients with hypertrophic cardiomyo- pathy have shown reversible perfusion abnormalities with unknown clinical significance. We performed this study to characterize dipyridamole Tl-201 SPECT imaging and correlate with clinical findings in patients with hypertrophic cardiomyopathy. Methods:Tl-201 SPECT was performed in 25 patients of hypertrophic cardiomyopathy with asymmetric septal hypertrophy and 20 normal controls after dipyridamole infusion (0.56 mg/kg. Myocardial wall was divided into 8 segments. Tl-201 uptake and relative washout rate were calculated. Results:Tl-201 SPECT showed significantly lower Tl-201 uptake in basal septal (81.3±3.4% vs 78.2±6.4%, p<0.05 and apical septal wall on stress (88.2±4.7% vs 83.9±6.5%, p<0.05 and higher apical septal (86.6±5.2% vs 89.2±3.1%, p<0.05 and apical anterior wall uptake (88.7%±4.0% vs 91.4±4.9%, p<0.05 on redistribution images in patients with hypertrophic cardiomyopathy. Basal lateral wall uptake of hypertrophic cardiomyopathy was significantly lower than normal control on both stress (84.7±3.5% vs 81.2 ±7.3%, p<0.05 and redistribution images (85.0±5.8% vs 76.8±7.2%, p<0.0001. The septum/lateral uptake ratio of patients on rest image was significantly higher than that of normal controls (0.98±0.07 vs 1.07±0.10, p<0.001. There was no difference in age, sex, symptom, cardiac medication and the parameters of 2D-echo including left ventricular outflow obstruction between subgroups of normal vs abnormal washout in patients with hypertrophic cardiomyopathy. Conclusion:Dipyridamole Tl-201 myocardial SPECT shows reduced