Background:

We aimed to evaluate clinical effects of additional heart

rate control by ivabradine on life quality score and 6-minute walking test

in patients with previously implanted biventricular cardiac resynchronization

therapy defibrillator (CRT-D) with ischemic heart failure under

regular treatment.

Methods:

Fifteen men and 14 women with a median age of 63 years

(range, 48

Y79 years) were studied. Twenty-one patients were in New York

Heart Association class II (8 patients were in class III), CRT-D implanted

previously, and with resting heart rates greater than 70 beats per

minute with sinus rhythm despite conventional medication. Patients were

given 2.5- to 7.5-mg ivabradine orally twice a day, and drug dosage was

titrated to decrease the patients’ average heart rate to 70 beats per minute.

Before and 3 months after ivabradine treatment, all patients underwent

extensive clinical, echocardiographic, and laboratory evaluation.

Results:

Ivabradine treatment produced dose-dependent reductions in

heart rate at rest and at peak exercise (91.9

T 6.3 to 71.7 T 4.8 and 114.4 T

7.6 to 96.8

T 4.8; P = 0.001 and P = 0.001, respectively). There were also

significant improvements in life quality score (52.4

T 9.5 to 37.9T7.8;

P

= 0.001) and 6-minute walking distance (278.7 T 85.8 to 373.3 T 94.0;

P

= 0.001) of patients. All patients with New York Heart Association

class III became class II after 3 months of ivabradine treatment.

Conclusion:

Heart rate reduction in a short-term period by ivabradine

produced significant improvements in exercise capacity and life quality

in patients with CRT-D and conventional therapy.