Adenosine infusion as a diagnostic tool in patients with chest pain. An echocardiographic study

Abstract

This study aimed to investigate the usefulness and potency of adenosine infusion to induce myocardial ischemia as compared with dynamic exercise, to determine the sensitivity of two-dimensional echocardiography in detecting an ischemic event compared with ECG and thallium-201 SPECT, to assess the accuracy of the adenosine stress test in detecting coronary artery disease and to evaluate the safety and tolerability of adenosine infusion. The study was performed in a total 162 individuals using 177 stress tests: 100 patients with known or suspected coronary artery disease, 15 patients with severe angina and spinal cord stimulation (adenosine test was performed twice without and with SCS), 20 patients with syndrome X (typical angina pectoris, positive exercise stress test and normal coronary angiograms), 17 patients with atypical chest pain, negative stress test and normal coronary angiograms, and ten healthy volunteers. Myocardial ischemia was induced by intravenous adenosine infusion at a maximal dose of 200µg|kg|min or by symptom-limited exercise stress test on the bicycle. An ischemic event was detected by two-dimensional echocardiography, ECG and thallium-201 SPECT, performed at baseline and at maximal stress, and clinically by onset, character and duration of the chest pain (Borg s scale 0-10). Regional wall motion analysis was estimated semiquantitavely - segmental analysis for the presence of transient wall motion abnormalities and reversible perfusion defects. Coronary angiograms were performed in 67 patients with suspected coronary artery disease. Angiograms were reviewed visually and lumen diameter narrowing =50% was considered as significant. Adenosine infusion at a dose of 140µg/kg/min proved at be at least as useful as dynamic exercise in inducing transient wall motion abnormalities; ECG was more accurate when it was combined with exercise; there was a very good correlation between two-dimensional echocardiography and thallium-201 SPECT, a concordance of 72%. The frequency of reversible perfusion defects was greater than frequency of transient wall motion abnormalities detected by two-dimensional echocardiography, 65% and 50%, respectively. Thallium-201 SPECT had superior sensitivity when compared with echocardiography, 88% and 69% respectively, specificity was higher with echocardiography, 100% vs. 67% respectively and both tests showed a similar accuracy, 82%, for SPECT vs. 77% for echocardiography (p=NS). Adenosine infusion induced chest pain and transient wall motion abnormalities in the majority of patients with syndrome X. Neither chest pain nor wall motion abnormalities were observed in healthy volunteers. Spinal cord stimulation did not affect general hemodynamics in patients with severe angina pectoris. Adenosine infusion induced both the chest pain and left ventricular dyssynergy in those patients. These adenosine-induced effects could be successfully suppressed by spinal cord stimulation. Although adverse events were common they were well tolerated and disappeared within seconds after termination of infusion. In conclusion, adenosine echocardiography is a safe, well tolerated and accurate method for pharmacological diagnostic testing in patients with chest pain.