The Effect of Ivabradine on the Heart Rate and Sympathovagal Balance in Postural Tachycardia Syndrome Patients

Abstract

ABSTRACT Background: Postural tachycardia syndrome (POTS) is a common form of chronic orthostatic intolerance. The remarkable increase in heart rate (HR) upon standing is the hallmark of this syndrome. Treatment of POTS patients is challenging and includes drugs that slow the HR. Ivabradine is a selective If channel blocker designed to slow the HR, as an anti-anginal agent. In view of its ability to slow the HR, we posited that ivabradine may be an ideal medication for treating POTS patients. This report provides the results of an investigation in which we studied ivabradine’s effect on the hemodynamics and sympathovagal balance in POTS patients. Methods: An open-label trial, without a placebo control, was performed in eight patients with POTS of two years’ standing. Characterization of symptoms, hemodynamics, autonomic function tests, and HR and blood pressure (BP) variability were determined while patients were in a supine position and during a 20-minute head-up tilt before and after a single oral dose of 7.5 mg ivabradine. Abbreviations: