Myocardial perfusion imaging and cardiac involvement in the indeterminate phase of Chagas disease.

Background: Myocardial perfusion imaging (MPI) has been used in the assessment of chagasic heart disease.

Objective: To investigate the value of gated-single photon emission computed tomography (gated-SPECT) MPI to detect early cardiac involvement in chagasic patients in the indeterminate phase, who present segmental motion abnormalities detected by tissue Doppler imaging (TDI)-derived strain.

Methods: Forty individuals (mean age: 25±2 years, 50% males) from an endemic area of Chagas disease and with positive serologic diagnosis, were included. All underwent gated-SPECT two-day (stress-rest) MPI and echocardiography.

Results: Thirty individuals (75%) showed a normal scan. In three cases (8%) the MPI was slightly abnormal, and in seven it was equivocal. In all cases with reversible defects, the affected segments were coincident with those with motion abnormalities. A post-stress left ventricular ejection fraction (LVEF) reduction > 5% (ΔLVEF < -5%) was found in 11 out of 40 individuals (28%). Both the phase-derived standard deviation and the histogram bandwidth showed a significant difference between post-stress and rest. In both cases there was a slight dyssynchrony at rest which normalized at post-stress.

Conclusions: A stress-rest gated-SPECT is a valid approach to detect early myocardial alterations, as well as intraventricular dyssynchrony in the indeterminate phase of Chagas disease in patients with segmental motion abnormalities previously detected by TDI-derived strain.