Effect of exercise level on the diagnostic accuracy of thallium-201 SPECT scintigraphy

The sensitivity of electrocardiographic ST analysis for detecting coronary artery disease is markedly decreased in patients unable to exercise vigorously. To determine the diagnostic accuracy of Thallium-201 SPECT scintigraphy at various exercise levels, we evaluated 179 patients without evidence of prior myocardial infarction or other confounding factors who performed symptom-limited exercise with Thallium-201 SPECT scintigraphy. Sensitivity decreased from 89% in those patients achieving greater than or equal to 85% of maximal heart rate to 63% in those achieving less than 65%. Like ST segment analysis, Thallium 201 SPECT scintigraphy has decreased diagnostic yield at low levels of exertion.