Myocardial thallium defects in apical hypertrophic cardiomyopathy are associated with a benign prognosis

We investigated whether myocardial thallium-201 defects in patients with apical hypertrophic cardiomyopathy are associated with an unfavorable clinical outcome, and additionally compared the presence of defects to echocardiography and angiography findings. Dipyridamole thallium-201 single photon emission tomography was performed in 26 apical hypertrophic cardiomyopathy patients, aged 41-78 (22 men, 6 women). Patients with or without perfusion defects were compared for echocardiographic measurements of wall thickness, chamber dimensions, and fractional shortening. Twelve patients underwent coronary angiography. The occurrence of cardiac events was evaluated during clinical follow-up for a mean period of 4.3 +/- 1.9 years (range: 1.0-7.0 year). Thirteen patients (50%) showed perfusion defects, which were predominantly reversible (fixed in 1) and mostly apical (9 of 13). Patients with and without defects did not differ in symptoms, EKG findings, echocardiographic morphology or fractional shortening (41 +/- 4 vs. 41 +/- 7%). Coronary angiography was normal in all patients in whom it was performed (nine with and three without defects). During follow-up, there were no deaths or myocardial infarction. Of the defect positive group, one case developed paroxysmal supraventricular tachycardia, and another had a cerebrovascular accident. Of the defect negative group, one case developed sick sinus syndrome, while another had a hospital admission for anginal pain. While reversible thallium defects in the absence of coronary artery disease occur frequently in patients with apical hypertrophic cardiomyopathy, the prognosis remains benign despite the presence of ischemia and there is no evidence for an association with adverse patient outcome.