Prolonged dipyridamole administration reduces myocardial perfusion defects in experimental chronic Chagas cardiomyopathy

Abstract

Background. Myocardial perfusion defects (MPD) due to coronary microvascular dysfunction is frequent in chronic Chagas cardiomyopathy (CCC) and may be involved with development of myocardial damage. We investigated whether MPD precedes left ventricular systolic dysfunction and tested the hypothesis that prolonged use of dipyridamole (DIPY) could reduce MPD in an experimental model of CCC in hamsters. Methods and results. We investigated female hamsters 6-months after T. cruzi infection (baseline condition) and control animals, divided into T. cruzi-infected animals treated with DIPY (CH 1 DIPY) or placebo (CH 1 PLB); and uninfected animals treated with DIPY (CO 1 DIPY) or placebo (CO 1 PLB). The animals were submitted to echocardiogram and rest SPECT-Sestamibi-Tc99m myocardial perfusion scintigraphy. Next, the animals were treated with DIPY (4 mg/kg bid, intraperitoneal) or saline for 30 days, and reevaluated with the same imaging methods. At baseline, the CH 1 PLB and CH 1 DIPY groups showed larger areas of perfusion defect (13.2 +/- 13.2% and 17.3 +/- 13.2%, respectively) compared with CO 1 PLB and CO 1 DIPY (3.8 +/- 2.2% e 3.5 +/- 2.7%, respectively), P <.05. After treatment, we observed: reduction of perfusion defects only in the CH 1 DIPY group (17.3 +/- 13.2% to 6.8 +/- 7.6%, P 5.001) and reduction of LVEF in CH 1 DIPY and CH 1 PLB groups (from 65.3 +/- 9.0% to 53.6 +/- 6.9% and from 69.3 +/- 5.0% to 54.4 +/- 8.6%, respectively, P <.001). Quantitative histology revealed greater extents of inflammation and interstitial fibrosis in both Chagas groups, compared with control group (P < .001), but no difference between Chagas groups (P >.05). Conclusions. The prolonged use of DIPY in this experimental model of CCC has reduced the rest myocardial perfusion defects, supporting the notion that those areas correspond to viable hypoperfused myocardium.