Feasibility of using ivabridine in adult congenital heart disease patients

Background Beta Blockers have been the main agent to control the heart rate in Fontan patients. Ivabridine which is a selective SA node inhibitor has been used in adult cardiac patient with successful result in controlling heart rate for those who did not respond to beta blockers alone. This agent has not been reported to be used in adult congenital heart disease patients. Objective To determine the feasibility of using ivabridine in patient with adult congenital heart disease and inappropriate sinus tachycardia who failed to respond to beta blockers. Methods 3 patients all with single ventricle physiology were on maximum tolerable dose of Beta Blockers, with inappropriate sinus tachycardia started on ivabridine. Average follow up was 52 weeks with regular holter monitor. Pro-BNP, 6 min walk test, and echocardiography at baseline and 24 weeks of follow up. Physical examination and interrogation for any detected side effect was done on each visit. Result At baseline the average heart rate was 100 ± 4 BPM, ivabridine started on with target dose 7.5 mg BD. The mean average heart rate at 12 weeks was 83 BPM, 78 BPM on 24 weeks, and 85 BPM on 52 weeks. There was no reported side effect by the patients or an effect on single ventricle function. Conclusion ivabridine can be used in single ventricle patients to reduce the heart rate in conjunction with beta blockers. However larger study is needed to assess its isolated long term effect on a diseased sinus node.