Background: The prognostic value of normal dual-isotope single photon emission computed tomography (SPECT), with technetium 99m-tetrofosmin for the stress images, is not well known. Furthermore, thallium-201 cross talk in the Tc-99m window may reduce the defect severity of the Tc-99m images.
Methods and results: In a consecutive series of 610 patients, 246 patients with normal rest and stress SPECT images by means of visual semiquantitative analysis were included. The patients' pre-test likelihood of coronary artery disease was determined, based on age, sex, symptoms, and the results of stress electrocardiography. Quality of life was assessed by using a mailed self-administered general quality-of-life questionnaire. We compared the mean scores (8 dimensions) of our study population with the scores of 1063 control subjects, sampled randomly out of the inhabitant register of a Dutch city. The mean follow-up period was 25+/-3 months. Compared with the control group, patients in our study scored lower (less perceived health) for all dimensions of the SF-36 (P<.05), suggesting a selection of symptomatic or otherwise diseased patients. The primary cardiac event rate was 0.4% per year. The cardiac events occurred in patients with an intermediate-to-high pre-test likelihood of disease and negative or nondiagnostic exercise electrocardiographic results. In a subset of patients with a high pre-test likelihood of coronary artery disease (more than 85%), the primary cardiac event rate was 0.7% per year.
Conclusions: Patients with normal results on dual-isotope myocardial perfusion scintigraphy, performed with Tc-99m-tetrofosmin for the stress images, have an excellent prognosis. Furthermore, our results suggest that Tl-201 cross talk in the Tc-99m window may be low and functionally and clinically unimportant.