[X syndrome--report of six cases]

Six patients (2 males and 4 females, mean age of 46 years) with X syndrome were reported in this paper. All patients presented with typical exertional angina pectoris. In 4 patients the angina had a variable threshold of onset, it often occurred at rest and occasionally nocturnally. The electrocardiogram during chest pain showed ST segment depression of more than 0.05-0.1 mV in all 6 patients. The treadmill or bicycle ergometer exercise test was positive in 4 cases (ST segment depression > 0.1 mV), equivocal in 1 (ST segment < 0.1 mV) in whom the 201Tl exercise myocardial perfusion scan showed sign of ischemia, and negative in 1 in whom atrial pacing at heart rate of 135 beats/min induced angina and ST segment depression of 0.1-0.15 mV. Echocardiograms and X ray chest films revealed no sign of ventricular hypertrophy or enlargement. The 201Tl exercise myocardial perfusion scan was performed in 5 patients, which showed signs of ischemia in 4 patients and suspected to have ischemia in 1. Left ventriculograms and coronary angiograms were normal in all 6 patients. Ergonovine provoking test (total dose of 0.4 mg) was negative in 5 patients, it was not performed in 1 in whom there was no evidence of coronary artery spasm by angiogram during appearance of electrocardiographic ischemic changes and chest pain. Left ventricular endomyocardial biopsy was performed in 1 patient, which showed significant smooth muscle cell proliferation in the medial layer of a small artery with diameter of 62.5 mu which produced narrowing of the lumen.(ABSTRACT TRUNCATED AT 250 WORDS)