Simultaneous measurement of left ventricular function and myocardial perfusion during a single exercise test: dual isotope imaging with gold-195 m and thallium-201.

The state of left ventricular function and myocardial perfusion are important determinants of prognosis in patients with coronary artery disease and information on both can be valuable for planning individual patient management. We have studied the feasibility of simultaneous measurement of left ventricular ejection fraction with ultra short-lived gold-195 m (half life 30.5 seconds) and myocardial perfusion with thallium-201, at rest and after exercise with a single-crystal gamma camera. The results with first-pass radionuclide angiocardiography (RNA) using gold-195 m at rest were reproducible and agreed closely with the results obtained using technetium-99 m equilibrium radionuclide angiocardiography (r = 0.93). Ejection fraction by first-pass gold-195 m RNA during semi-supine ergometric exercise decreased by greater than 5% in 13 out of 18 patients with coronary artery disease and stable angina. Simultaneous myocardial imaging with thallium-201 was abnormal in all patients. The change in regional wall motion abnormality score during exercise correlated with the change in myocardial perfusion (r = 0.71, P less than 0.01) and with the change in global left ventricular ejection fraction (r = 0.77, P less than 0.001). The widely differing energy levels and half-lives of gold-195 m and thallium-201 made it possible to separate clearly the images due to each radionuclide. This study has demonstrated the feasibility of simultaneous or sequential assessment of left ventricular function and myocardial perfusion during a single exercise test, a technique which can offer advantages in clinical evaluation of patients with coronary artery disease.