Author + information
- Thomas H. Marwick, MD, PhD∗ ( and )
- Wojciech Kosmala, MD, PhD
- ↵∗Menzies Research Institute Tasmania, Private Bag 23, Hobart, Tasmania 7001, Australia
We appreciate the interest of Drs. Santos and Leite-Moreira in our work (1). We completely agree with their comments regarding the importance of heart rate (HR) as a contributor to diastolic function. Ivabradine has a unique position as a negative chronotrope that is not a negative inotrope. Indeed, the rationale for treatment with ivabradine in our study was to avoid the reduction in the duration of diastole that follows from an increase in HR.
Disturbances in the relationship between HR and myocardial relaxation in failing hearts might represent another aspect supporting the use of If channel inhibition in this context. Although ivabradine has multiple effects, a direct effect on myocardial relaxation may be an important benefit. In addition, the potential effects of ivabradine on arterial compliance and afterload in heart failure with preserved ejection fraction (HFpEF) require, in our view, further evaluation.
The patient selection in our study was focused on patients in whom exertional dyspnea develops, which is related in part to shortening of diastole during tachycardia. The clinical effects of ivabradine are being investigated in a large multicenter study, but it is likely that this will involve a heterogeneous group. We would like to draw the attention of readers to the need for studying well-characterized subgroups of the very heterogeneous entity of heart failure with preserved ejection fraction.
- American College of Cardiology Foundation