Correlation of adenosine echocardiography and thallium scintigraphy

Abstract

Echocardiography and thallium-201 imaging with coronary vasodilators such as dipyridamole have been shown to be useful in detecting the presence and prognostic significance of coronary artery disease. Adenosine, a potent and direct coronary vasodilator, has a shorter physiologic half-life than dipyridamole, which exerts its effect by blocking the cellular uptake of adenosine. Because of the potential advantage of dipyridamole, we undertook this study to determine the correlation of adenosine echocardiography with thallium scintigraphy. Forty-two patients (18 men and 24 women; mean age 64) who were unable to undergo treadmill exercise and were known or suspected to have coronary artery disease were studied. A baseline echocardiogram was obtained in four standard views followed by adenosine infusion at a rate of 140 μg/kg/min for 6 minutes. Thallium-201 was administered 3 minutes into the infusion while a second echocardiogram was performed. Thallium-201 imaging was begun immediately after the infusion of adenosine and repeated 4 hours later. Sixteen patients underwent coronary angiography within 1 month of the adenosine echocardiogram and thallium-201 study. At the peak infused dose of adenosine there was a significant increase in heart rate (12 beats/min; p = 0.0001) and rate-pressure product (1.3 × 10 3 beats/min × mm Hg; p = 0.02) and statistically insignificant decreases in systolic and diastolic blood pressures. Sixty-two percent of patients experienced side effects during the adenosine infusion, with chest pain, shortness of breath, and flushing occurring most frequently. These side effects resolved within 1 to 2 minutes after the infusion was stopped. Ischemic electrocardiographic changes occurred in 19% of patients. Third-degree atrioventricular block developed in only one patient. The echocardiogram and thallium-201 results were concordant in 36 (92%) of 39 patients with technically adequate echocardiographic images and in a subset of patients were concordant with coronary angiography in 56% and 69% of patients, respectively. Adenosine echocardiography and adenosine thallium were abnormal in 71% and 86% of patients, respectively, with more than two-vessel coronary artery disease. However, only 36% of patients with one-vessel disease had abnormal adenosine echo or thallium results. There is excellent agreement between adenosine echocardiography and adenosine thallium scintigraphy. Adenosine echocardiography and adenosine thallium are highly concordant with coronary angiography in a small subset of patients with multivessel disease.