• Riccardo Cappato, Serenella Castelvecchio, Cristian Ricci, Elisabetta Bianco, Laura Vitali-Serdoz, Tomaso Gnecchi-Ruscone, Mario Pittalis, Luigi De Ambroggi, Mirko Baruscotti, Maddalena Gaeta, Francesco Furlanello, Dario Di Francesco, and Pier Paolo Lupo.
• Arrhythmias and Electrophysiology Center, I.R.C.C.S. Policlinico San Donato, Milan, Italy. rcappato@libero.it
• J. Am. Coll. Cardiol. 2012 Oct 9; 60 (15): 1323-9.

ObjectivesThe purpose of this study was to investigate the role of ivabradine in the treatment of symptomatic inappropriate sinus tachycardia using a double-blind, placebo-controlled, crossover design.BackgroundDue to its I(f) blocking properties, ivabradine can selectively attenuate the high discharge rate from sinus node cells, causing inappropriate sinus tachycardia.MethodsTwenty-one patients were randomized to receive placebo (n=10) or ivabradine 5 mg twice daily (n=11) for 6 weeks. After a washout period, patients crossed over for an additional 6 weeks. Each patient underwent symptom evaluation and heart rate assessment at the start and finish of each phase.ResultsAfter taking ivabradine, patients reported elimination of >70% of symptoms (relative risk: 0.25; 95% CI: 0.18 to 0.34; p<0.001), with 47% of them experiencing complete elimination. These effects were associated with a significant reduction of heart rate at rest (from 88±11 beats/min to 76±11 beats/min, p=0.011), on standing (from 108±12 beats/min to 92±11 beats/min, p<0.0001), during 24 h (from 88±5 beats/min to 77±9 beats/min, p=0.001), and during effort (from 176±17 beats/min to 158±16 beats/min, p=0.001). Ivabradine administration was also associated with a significant increase in exercise performance. No cardiovascular side effects were observed in any patients while taking ivabradine.ConclusionsIn this cohort, ivabradine significantly improved symptoms associated with inappropriate sinus tachycardia and completely eliminated them in approximately half of the patients. These findings suggest that ivabradine may be an important agent for improving symptoms in patients with inappropriate sinus tachycardia.Copyright © 2012 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

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