Thallium Scans in Patients with Syndrome X

Symptom-limited maximal treadmill exercise tests were performed in 20 patients (mean age 45±1.7; 10 male and 10 female) who had typical angina pectoris, and normal coronary angiography. In all patients, the thallium scans (SPECT) were initiated in 5-8 minutes after the injection of thallium. The patients did not have any disease which could affect the thallium scan. None gave a history or showed electrocardiographic (ECG) evidence of previous myocardial infarction. Resting electrocardiogram was normal in 7 patients, but ECG's showed ischemic changes in 9 patients, right bundle-branch block in 2 patients, frequent ventricular premature beats in 1 patient, atrial fibrillation in 1 patient. The exercise test was electrocardiographically positive (=1 mm ST depression in 16 patients, 80 %) and negative in the remaining . Nineteen patients (95 %) had abnormal thallium scans and only one patient a normal thallium scan. The patient with normal scan had abnormal resting ECG and exercise test. The finding of abnormal thallium scans in two patients with a normal ECG and exercise test emphasizes the importance of thallium test in the diagnosis of syndrome X. In conclusion, thallium defects described in 19 of 20 patients with angina and normal coronary arteriograms suggest that microvascular angina (syndrome X) may be commoner than is generally appreciated.