FREQUENCY OF SYSTEMIC MICROVASCULAR DYSFUNCTION IN SYNDROME-X AND IN VARIANT ANGINA

In addition to coronary vascular abnormalities, patients with syndrome X and variant angina often have systemic vascular symptoms. To determ ine whether these patients exhibit a generalized abnormality of vasore activity, we used high-resolution ultrasound to compare flow responses and endothelial function in the brachial artery in 21 patients with s yndrome X, 15 patients with variant angina, and 20 healthy controls. A rterial diameter was measured at rest, after reactive hyperemia (endot helium-dependent flow-mediated vasodilation), and after sublingual gly ceryl trinitrate (endothelium-independent vasodilation). The magnitude of hyperemic flow response was measured after transient forearm occlu sion. Flow-mediated dilation in the brachial artery did not differ amo ng patients with syndrome X, variant angina, and controls (2.7 +/- 2.3 %, 3.8 +/- 3.5%, and 4.2 +/- 3.0%), Endothelium-independent vasodilati on in the brachial artery was similar in the 3 groups (16.0 +/- 7.2%, 12.7 +/- 4.6%, and 14.8 +/- 4.9%). Despite a considerable overlap, rea ctive hyperemia was lower in patients with syndrome X than in patients with variant angina and controls (342 +/- 86% vs 466 +/- 184% and 452 +/- 104%; p < 0.05). These findings indicate that a substantial propo rtion of patients with syndrome X have a systemic microvascular abnorm ality, whereas variant angina is predominantly a segmental disorder of conduit vessels.