Anti-ischemic and anti-anginal effects of thoracic epidural anesthesia versus those of conventional medical therapy in the treatment of severe refractory unstable angina pectoris.

Abstract

Cardiac sympathetic blockade by thoracic epidural anesthesia (TEA) dilates stenotic coronary arteries and has been used to control pain in patients with unstable angina. The aim of the present study was to evaluate the potential anti-ischemic effects of cardiac sympathetic blockade by TEA in severe, refractory, unstable angina. Forty patients with unstable angina refractory to standard anti-anginal therapy were randomized to receive either continuous epidural infusion of bupivacaine (TEA, Th1 to Th5) or to standard anti-anginal therapy including beta-blockers, calcium antagonists, aspirin, heparin, and nitroglycerin infusion (control group). The primary end points were number of anginal attacks and severity of myocardial ischemia assessed by 48-hour ambulatory Holter monitoring. The incidence of myocardial ischemia was lower in the TEA group (22% versus 61%; P<.05). The number of ischemic episodes per patient was 1.0+/-0.6 in the TEA group and 3.6+/-0.9 in the control group (P<.05). The episode duration per patient was 4.1+/-2.5 minutes and 19.7+/-6.2 minutes in the TEA and the control groups, respectively (P<.05). The mean area-under-the-ST-time-curve was 6.8+/-4.3 and 32.2+/-14.3 (mm-min) in the TEA and the control groups, respectively (P<.05). Fifteen anginal attacks were recorded in the control group and one attack in the TEA group (0.83+/-0.21 versus 0.06+/-0.06/patient, respectively, P<.01). The anti-ischemic and anti-anginal effects of continuous TEA are superior to those of conventional therapy in the treatment of refractory unstable angina.