If current inhibitor ivabradine in patients with idiopathic dilated cardiomyopathy: Impact on the exercise tolerance and quality of life

Background: Evidence supported a beneficial effect of ivabradine on clinical outcome of patients with systolic heart failure, and a sinus heart rate (HR) >= 70 bpm. We explored the effect of ivabradine, vs. placebo, added to evidence-based treatment on exercise tolerance and quality of life in patients with idiopathic dilated cardiomyopathy. Methods: We enrolled 43 consecutive patients with dilated cardiomyopathy of no apparent cause, a left ventricular ejection fraction (LVEF) < 40%, New York Heart Association class >= II, sinus HR >= 70 bpm, and background evidence-based anti-failure medications. Ischemic heart disease was ruled out. Patients were randomized (1: 1) to receive ivabradine or placebo. Ivabradine was titrated up gradually till 7.5 mg twice daily, or a HR < 60 bpm, and continued for 3 months. Symptom-limited exercise tolerance test was performed, and quality of life was assessed by the Minnesota Living With Heart Failure Questionnaire at 0, and 3 months. Results: Forty-three patients were randomized to ivabradine (n = 20), or placebo (n = 23). Mean age was 50.8 +/- 14.5 years (53.5% males). Mean HR was 85 +/- 12 bpm, and mean LVEF was 32 +/- 6%. Mean dose of carvedilol was 31.2% of the target dose. Baseline HR, blood pressure, exercise tolerance, Minnesota questionnaire score, and left ventricular systolic function were comparable between the two groups (p > 0.05 for all). At 3 months, mean dose of ivabradine was 6.8 mg bid. Ivabradine-treated patients had a lower HR, and improved left ventricular dimensions and systolic function, versus placebo-treated ones (p < 0.05 for all). HR dropped by a mean of 14 bpm in the ivabradine group, corrected for placebo. Both exercise tolerance, and Minnesota questionnaire score were better in the ivabradine group (p < 0.05 both). Ivabradine was well-tolerated. Conclusions: In symptomatic patients with idiopathic dilated cardiomyopathy, the addition of ivabradine, vs. placebo, to evidence-based treatment, reduced HR, and improved functional capacity, at short-term follow-up.