Rest-redistribution thallium-201 myocardial scintigraphic study in cardiacamyloidosis

Background: Histopathological study in amyloid heart demonstrates that myoc yte destructed by the extracellular deposition of amyloid protein together with viable myocyte is present. We hypothesized that rapid thallium washout may be found in amyloid heart as in regions which have a mixture of viable myocyte and scar tissue in patients with myocardial infarction. Thus, the purpose of this study was to evaluate the extent and severity of myocardial damage due to amyloid deposits using the washout rate of the tracer on res t-redistribution thallium-201 (Tl-201) myocardial scans in cardiac amyloido sis patients. Methods: Rest-redistribution Tl-201 myocardial scintigraphy w as performed in 5 patients with biopsy-proved systemic amyloidosis with car diac involvement (amyloidosis group). The initial and delayed images were o btained 15 min and 4 h, respectively, after intravenous injection of the tr acer of 111 MBq. Washout rate of the tracer was calculated. Twelve patients with no apparent heart disease served as controls (control group). Results : Mean washout rate of the whole heart was higher in the amyloidosis group than in the control group (56 +/- 9% vs 36 +/- 6%, p < 0.001). Particularly , 4 of the 5 patients in the amyloidosis group presented a very high rate o f thallium clearance which ranged from 57 to 61%, and died in less than a y ear. In the remaining 1 patient who had a normal washout rate of the tracer in the first study, it changed from 40 to 53% during the 5-year follow-up period. Conclusions: Washout rate in the setting of rest and delayed Tl-201 images may represent the severity of amyloid depositions in the myocardium and may provide prognostic information.