OBJECTIVE We sought to demonstrate that brachytherapy reduces coronary spasm in refractory and highly symptomatic variant angina. BACKGROUND In some patients with variant angina due to extensive vasoconstriction, intensive drug therapy fails to sufficiently relieve symptoms. METHODS In 18 patients with frequent angina episodes despite triple anti-anginal therapy, coronary spasm was induced by intracoronary acetylcholine (ACh) infusion. Five patients had spasm in a second vessel. Intracoronary radiation (20 Gy) was applied to vasospastic segments using a beta-emitting ((32)P) wire source centered within a Galileo balloon. Parameters of vessel function before and after brachytherapy were investigated. RESULTS Before brachytherapy, artery diameters decreased (p < 0.0001) from 2.8 +/- 0.4 mm to 1.0 +/- 0.4 mm for the first vessels and from 3.1 +/- 0.3 mm to 1.0 +/- 0.2 mm for the second vessels. After brachytherapy (143 +/- 106 and 80 +/- 52 days for first and second vessels, respectively), ACh-induced vasoconstriction was significantly reduced. The ACh-induced changes in artery diameter before and after brachytherapy were -1.5 +/- 0.5 mm and -0.5 +/- 0.3 mm (p < 0.0001) for the first vessels and -1.4 +/- 0.3 mm and -0.4 +/- 0.2 mm (p < 0.01) for the second vessels, respectively. In non-irradiated spastic vessels, ACh-induced vasoconstriction remained unchanged (e.g., -1.7 +/- 0.6 mm, -1.6 +/- 0.3 mm, and -1.5 +/- 0.5 mm for second vessels, at first investigation, first follow-up, and immediately before brachytherapy, respectively). Angina frequency decreased from 15.6 +/- 6.0 to 2.2 +/- 2.4 angina episodes/week (p < 0.001) in treated patients. CONCLUSIONS Brachytherapy is a potential therapy in patients with highly symptomatic variant angina.