Cardiac syndrome X: clinical characteristics and left ventricular function. Long-term follow-up study

Our aim was to study the clinical characteristics and evolution of symptoms and left ventricular function in a clinically homogeneous group of patients with syndrome X (angina pectoris, positive exercise test results and normal coronary arteriograms).

The syndrome of angina with normal coronary arteriograms is heterogeneous and encompasses different pathogenetic entities. These characteristics may contribute to the existing controversy concerning the cause of syndrome X.

We studied 99 patients with syndrome X (78 women, 21 men; mean age +/- SD 48.5 +/- 8 years). All underwent clinical characterization, ambulatory electrocardiographic (ECG) monitoring and echocardiographic assessment of left ventricular function during a follow-up period of 7 +/- 4 years.

The syndrome was more common in women than in men. Of the women, 61.5% were postmenopausal before the onset of chest pain. All 99 patients had exertional angina, and 41 also had rest angina. The average duration of episodes of chest pain was > 10 min in 53% of patients. Sublingual nitrate was effective for relief of pain in 42% of patients. Transient ST segment depression was observed during ambulatory ECG monitoring in 64 patients and myocardial perfusion abnormalities in 22. During the first stage of the exercise test, 32 patients had an increase > 20 mm Hg in systolic blood pressure and showed an earlier onset of ST depression and shorter exercise time than did patients whose blood pressure increased < or = 20%. During follow-up, no deaths or myocardial infarctions occurred, ventricular function was unchanged (shortening fraction 35.4 +/- 4% vs. 35.6 +/- 3%; heart failure developed in only one patient), systemic hypertension occurred in eight patients and conduction disturbances in four. Symptoms lessened in 11 patients, were variable or unchanged in 64 and worsened in 24.

Syndrome X, as defined in this study, occurs predominantly in postmenopausal women. Patients usually have chest pain typical for angina, but conventional antianginal treatment is not often successful. Myocardial perfusion abnormalities occur in a small proportion of patients. Long-term survival is not adversely affected, and deterioration of cardiac function rarely occurs.