Safety and Tolerability Study of AZD4831 in Patients With Heart Failure.

This is a randomized, double-blind, placebo controlled, parallel group, multicentre study in patients with Heart Failure with preserved Ejection Fraction (HFpEF) and mid-range Ejection Fraction (HRmrEF). The study will be conducted at approximately 15 sites in 5 countries (USA, Sweden, Denmark, Finland, Netherlands). Patients suitable for the study will be checked for eligibility, signing the informed consent and enrolled to the study at visit 1. The study will be divided into two parts, Part A and Part B. In part A 37 patients will be randomized at visit 2 in a 2:1 ratio to once daily dosing of AZD4831 or matching placebo for approximately 90 days. After approximately 30 days of treatment, an interim analysis will be done to analyse the safety, tolerability and target engagement. After the evaluation, the randomization to Part B may proceed. In Part B the approximate 59 remaining patients will be randomized and treated for approximately 90 days.