14 CLINICAL STUDIES
In two crossover comparative studies involving 319 subjects who could exercise (including 106 healthy volunteers and 213 patients with known or suspected coronary disease), adenosine injection and exercise thallium images were compared by blinded observers. The images were concordant for the presence of perfusion defects in 85.5% of cases by global analysis (patient by patient) and up to 93% of cases based on vascular territories.
In the two studies, 193 patients also had recent coronary arteriography for comparison (healthy volunteers were not catheterized). The sensitivity for detecting angiographically significant disease (≥ 50% reduction in the luminal diameter of at least one major vessel) was 64% for adenosine injection and 64% for exercise testing. The specificity was 54% for adenosine injection and 65% for exercise testing. The 95% confidence limits for adenosine injection sensitivity were 56% to 78% and for specificity were 37% to 71%.
Intracoronary Doppler flow catheter studies have demonstrated that a dose of intravenous adenosine injection of 0.14 mg/kg/min produces maximum coronary hyperemia (relative to intracoronary papaverine) in approximately 95% of cases within two to three minutes of the onset of the infusion. Coronary blood flow velocity returns to basal levels within one to two minutes of discontinuing the adenosine infusion.