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
Fifteen men and 14 women with a median age of 63 years
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.
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;
= 0.001) and 6-minute walking distance (278.7 T 85.8 to 373.3 T 94.0;
= 0.001) of patients. All patients with New York Heart Association
class III became class II after 3 months of ivabradine treatment.
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.