Effect of thallium-201 blood levels on reversible myocardial defects.

To determine if 201Tl plasma blood levels correlate with the presence of reversible myocardial defects during exercise testing, 14 patients with stable coronary artery disease underwent two separate exercise 201Tl stress tests. Between initial and delayed imaging, on one test the patients drank an instant breakfast drink (eating) and on the other they drank an equivalent volume of water as a control (H2O). Thallium-201 imaging was performed immediately postexercise, immediately after eating/H2O and 210 min after eating/H2O. Between initial and immediate post eating/H2O images 201Tl reversible defects occurred in 27/38 regions in the H2O test versus 15/38 regions in the eating test (p = 0.02). Over this early time period, plasma 201Tl activity was significantly higher in the H2O test than eating test (p less than 0.05). In conclusion, early reversal of 201Tl defects may, in part, be the result of higher plasma 201Tl activity early after initial postexercise 201Tl imaging.