Background and Objectives : Exercise myocardial perfusion scans in patients with
hypertrophic cardiomyopathy have shown reversible perfusion abnormalities with
unknown clinical significance. We performed this study to characterize dipyridamole
T1-201 SPECT imaging and correlate with clinical findings in patients of hypertrophic
cardiomyopathy.
Methods : T1-201 SPECT was performed in 25 patients of hypertrophic cardiomyopathy
with asymmetric septal hypertrophy and 20 normal controls after dipyridamole infusion
(0.56㎎/㎏). Myocardial wall was divided into 8 segments. T1-201 uptake and relative
washout rate were calculated.
Results : T1-201 SPECT showed significantly lower T1-201 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%, 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, p0.001). 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
inpatients with hypertrophic cardiomyopathy.
Conclusion : Dipyridamole T1-201 myocardial SPECT shows reduced coronary
vasodilatory capacity of myocardium, especially septum in patients with hypertrophic
cardiomyopathy. High septal/lateral uptake ratio on redistribution image may be a
characteristic finding. However, no correlation between abnormal T1-201 washout and
clinical findings was observed.
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