USEFULNESS OF HYPERVENTILATION TL-201 SINGLE-PHOTON EMISSION COMPUTED-TOMOGRAPHY FOR THE DIAGNOSIS OF VASOSPASTIC ANGINA

To establish a safe and sensitive diagnostic procedure for detecting c oronary vasospasm, we utilized 201-thallium myocardial SPECT combined with hyperventilation (HV-SPECT) in 29 patients with vasospastic angin a (VAP) and 11 controls.Twenty-five of 29 patients with VAP and 5 of i i controls developed transient perfusion defects on HV-SPECT, resultin g in a sensitivity and specificity calculated at 86% and 55%, respecti vely. Overall accuracy in identifying corresponding vessels with coron ary vasospasm was 67%; it was 83%, 75% and 42% for patients with 1, 2 and 3 vessel spasm, respectively. Coronary vasospasm tended to be iden tified more accurately in the left anterior descending branch and the right coronary artery than in the circumflex branch (75%, 71% and 50%, respectively). The hyperventilation test induced ischemic ECC changes in 11 of 29 patients with VAP, yielding a sensitivity of 38%. Analyzi ng the washout rate of HV-SPECT in patients with VAP, both the extent and severity scores of patients with ischemic ECG changes were larger than those of patients without. No serious complications occurred duri ng HV-SPECT. In conclusion, HV-SPECT was a safe and sensitive procedur e as a primary diagnostic approach for VAP. From the results of washou t analysis, HV-SPECT could detect more mild myocardial ischemia than c ould the EGG, and seemed quite useful especially for detecting coronar y vasospasm accompanied by minimal ischemic ECG changes.