Does nitroglycerine enhance detection of viable myocardium by Tl-201 SPECT?

It is suggested that sublingual nitroglycerine can improve the ability of Tl-201 for detection of viable myocardium. Methods and Results: In a randomized, double blind study, 50 patients who had fixed defects on stress-redistribution scan were randomized into two groups. In group 1,patients received 0.4-0.8 mg sublingual nitroglycerine before Tl-201 re-injection. In group 2, re-injection of Tl-201 was performed without any previous intervention. In group 1, 11/25 of the patients (44%) showed improved reversibility after Tl-201 re-injection compared with 9/25 patients (36%)in group 2(P=0.56).Moreover, 6/50 of all patients showed reverse redistribution. This pattern was observed in 4/25 (16%) patients in group 1 and 2/25 (8%) patients in group 2 (P=0.38). Conclusion: Our results reveal that nitroglycerine has no significant effect either on detection of reversible myocardium by Tl-201 SPECT or upon reverse redistribution occasionally observed following Tl-201 re-injection