Abstract 9361: Ivabradine in Inappropriate Sinus Tachycardia: an Appropriate Alternative.
Introduction: Inappropriate sinus tachycardia (IST) is a challenging clinical syndrome characterized by elevation of heart rate (HR) disproportional to the physiologic demand. The incomplete understanding of the underlying mechanisms is associated to a wide-ranging, but no so effective and often not well tolerated, therapeutic interventions. Ivabradine, a selective sinus node If current inhibitor, has been successfully used in some cases. We present the first case series using ivabradine for treatment of IST.
Methods: From September 2008 to April 2010, 16 patients (PP) complaining palpitations (10 women, 39±13 year-old) were diagnosed of IST. All PP presented normal echocardiograms and secondary causes of tachycardia were excluded. 5 PP (31%) received treatment for hypertension with ACE inhibitors and 6 PP (37%) were diagnosed and treated for anxious-depressive disorder. 5 PP (31%) had been previously treated with beta-blockers and stopped because of side effects. PP were treated with 5 mg of ivabradine twice a day, and 7.5 mg if incomplete response was observed. Holter recordings were performed to evaluate the HR before and during treatment and PP were clinically followed using the SF-36 Health Survey.
Results: Holter recordings pre-treatment showed an average max HR of 153±13 bpm, a mean HR of 97±7 bpm (mean day-time HR of 105±8 bpm) and min HR of 55±13 bpm. Pre-treatment SF-36 Health Survey showed a mean score of 58.1, with a physical status score of 57.7 and mental status score of 57.9. The mean dosis of ivabradine was 6±1.2 mg. Holter recordings during treatment showed a statically significant reduction of average max HR (135±19 bpm), mean HR (79±9 bpm), mean day-time HR (86±11 bpm), and min HR (46±6 bpm) (Wilcoxon analysis, p< 0.05). A significant clinical improvement was also observed showing during treatment SF-36 mean score of 75.3, with a physical status score of 74.1 and mental status score of 76.5, (Wilcoxon analysis, p 0.001). One patient quit treatment because of gastrointestinal intolerance.
Conclusions: This is the first case series of PP diagnosed of IST under ivabradine treatment evaluating HR response and quality of life improvement. Ivabradine is an effective and well tolerated alternative for IST, where other drugs are often worse tolerated.
- © 2010 by American Heart Association, Inc.