Pulse Reduction On Beta-blocker and Ivabradine Therapy

The Pulse Reduction on Beta-blocker and Ivabradine Therapy (PROBE-IT) Study is a double-blind, randomized, two-arm parallel group, placebo-controlled design that compares the effect of heart rate reduction on ventricular reverse remodeling (assessed by LVEF change at 24 weeks) and on the beta1-gene signaling network in NYHA Class I-III HFrEF patients with an idiopathic dilated cardiomyopathy etiology (HFrEF/IDC), who are in sinus rhythm and whose heart rates remain ≥ 70 bpm on target or maximally tolerated doses of beta-blockers to which they have evidence of non-response by LVEF (\< 5 absolute percentage points). Eligible patients will be randomized (2:1) to blinded treatment with ivabradine or matching placebo and will be initiated as per Corlanor® prescribing information over 4 weeks. The dose at 4 weeks post randomization will be considered the intention-to-treat end of titration dose, but further dose adjustment can be made based on clinical factors. The primary endpoint, i.e., effect of heart rate reduction on reverse remodeling (LVEF), will be assessed after 24 weeks. LV phenotyping by 3D-echocardiography, endomyocardial biopsy and coronary sinus sampling for cardiac norepinephrine levels will be performed at baseline and at 24 weeks. Exercise testing at baseline will be performed to assess level of beta blockade. Upon completion of the study, gene expression in endomyocardial biopsy tissue samples for each patient will be quantified using RNA-seq and quantified with respect to phenotypic measurements including LVEF and heart rate changes. After the Week 24 Visit, patients will return for an End-of-Study Visit and be offered open label ivabradine with dose initiation accomplished by stopping study drug and starting Corlanor at 5 mg BID or 2.5 mg BID if the patient is taking that dose of study drug. Investigators and patients will not be informed of the blinded study drug assignment at the time of study completion.