Equivalence between adenosine and exercise thallium-201 myocardial tomography: A multicentre, prospective, crossover trial

Objectives. The study was designed to compare pharmacologic and exercise stress during thallum-201 single-photon tomography in a multkenter prospective crossover trial. Background. Both exercise and adenosine myocardial perfusion imaging have high sensitivity and specificity for detection of coronary artery disease. However, few data are available comparing these two stress tests in the same patients. Methods. The study group consisted of 175 subjects: 55 healthy volunteers and 120 patients with suspected coronary artery disease. All subjects underwent two thalium tomograpltic tests performed 30 days apart, one during intravenous administration of adenosine (140 μg/kg per min for 6 min) and one during exercise stress. All images were computer quantified and interpreted without knowledge of the stress test performed. Interpretation agreement was assessed by kappa and Z statistics. Results. Agreement on the presence of normal or abnormal tomograms by adenosine and exercise scintigraphy was 82.8% by visual analysis with kappa and Z statistics of 0.65 (p < 0.0001) and 11.1 (p < 0.00001), respectively. The agreement by computer quantification was 86% with kappa amd Z statistics of 0.709 (p < 0.0001) and 12.2 (p < 0.00001), respectively. Agreement on localisation of the perfusion defect to a specfic coronary vascular territory varied from 82.7% to 91.4% with highly significant kappa and Z statistics (p < 0.0001). There was a good correlation between quantified perfusion defect size by adenosine and exercise (r = 0.80, p < 0.0001), but the values for defect size were significantly greater by adenosine scintigraphy (p = 0.0073). Adenosine side effects were frequent but transient and ceased spontaneously in most subjects within 1 to 2 min after the infusion was discontinued. Conclusions. Adenosine thallium-201 scintigraphy provides diagnostic information similar to that of exercise scintigraphy, although values for defect sizes are greater with adenosine.