BACKGROUND: Regional left ventricular segmental wall motion impairment is an early marker of chronic Chagas cardiomyopathy. We have recently shown that dysynergy may be reversed in some ventricular regions by post-extrasystolic potentiation. Despite normal epicardial coronary arteries, patients with Chagas cardiomyopathy have perfusion defects, raising the possibility that myocardial hibernation could be responsible for the wall motion abnormalities reversed during post-extrasystolic potentiation. METHOD: Twentytwo consecutive patients with chronic Chagas cardiomyopathy underwent coronary angiography, left ventricular contrast angiography and stress-redistribution-reinjection thallium-201 myocardial scintigraphy for the assessment of the perfusion status in left ventricular segments showing the presence of post-extrasystolic potentiation. RESULTS: No significant coronary artery stenosis was seen in any of the patients. Post-extrasystolic potentiation was seen in at least one left ventricular segment in 14 of the 22 patients. It occurred in ventricular areas with baseline moderate to intense wall motion disorders, but not with dyskinesis. These patients showed an improvement in the average myocardial wall motion scores of 1.49 ± 0.73 to 1.36 ± 0.76 from the baseline to the post-extrasystolic beat (P < 0.05). In these areas, myocardial perfusion was normal or only mildly impaired, and ischemia was not induced by exercise or pharmacological stress. CONCLUSION: The present results do not support the hypothesis of hibernating myocardium caused by microvascular perfusion disorders in chronic Chagas cardiomyopathy.
Chagas disease; Myocardial contraction; Electric stimulation
