Abstract 5963: Prevention of Tilt-Table Induced Vasovagal Response by Angiotensin-Converting Enzyme Inhibition
The use of various pharmacologic agents has been proposed for the preventive treatment of vasovagal syncopal episodes, with conflicting efficacy results from various studies. Angiotensin-converting enzyme inhibitors (ACEIs), although reported in small studies to have a beneficial effect in patients with vasovagal syncope, have not been generally accepted as part of conventional treatment in such patients. Our population consisted of 125 consecutive patients (60 male, mean age 40±15 years), with a positive head-up tilt-table testing (HUTTT) (cardioinhibitory or vasodepressive or mixed response), who were randomized to receive either the ACEI fosinopril (N=63), at a dose of 10 mg qd, or placebo (N=62), for 30 days. They were then submitted to a new HUTTT (80 degrees, before and after infusion of isoproterenol, at a max. rate of 5 mcg/min). Before randomization, the patients were stratified according to the use of other vasoactive agents. Physicians performing the HUTTT were blinded as to each patient’s randomization group. Twenty-eight (44%) of fosinopril-treated patients were positive in the second HUTTT versus 52 (84%) in the placebo group (p=0.015). In a multivariate analysis, entering, apart from the treatment group, patient age, gender, smoking habit, hypertension, the use of beta-blocking agents and various demographic factors, with a negative result in the second HUTTT as the dependent variable, female gender, younger age and the use of fosinopril were independently associated with a negative repeat HUTTT. The present study reports a potential preventive effect of ACEIs in vasovagal syncope and indicates that younger, female patients, taking fosinopril were more likely to have a negative repeat HUTTT. The observed effect may be related to the ability of ACEIs to reduce cardiac wall tension, thus decreasing the activation of C-mechanoreceptors, as well as to their potential to inhibit angiotensin-related catecholamine release.