The study will enroll patients in 2 cohorts in parallel: 1 cohort of patients with heart failure with preserved ejection fraction (HFpEF) and 1 cohort of patients with heart failure with reduced ejection fraction (HFrEF). Each cohort plans to enroll at least 7 evaluable patients.~All patients will receive the same sequence of 5 intra-arterial (IA) infusions into the brachial artery, consisting of a baseline saline infusion of approximately 20 minutes, followed by 3 sequential infusions of AZD3427 at ascending doses of approximately 10 minutes (each) and a washout saline infusion of approximately 15 minutes.~For each patient, the study will last at least 51 days and up to 99 days, including:~A screening period of 1 to 42 days (which will include baseline echocardiography)~A single-day treatment period during which patients will stay at study site until at least 4 hours after the end of infusions~A follow-up period of 49 to 56 days after the end of the last infusion including:~A follow-up phone call on Day 2 (within 24 ± 6 hours post-infusion) A follow-up visit on Day 8 (+ 3 days) A follow-up visit on Day 29 (± 2 days) A follow-up visit on Day 50 (+ 7 days)
The primary purpose of this mechanistic study is to evaluate the vasodilatory effects of AZD3427 in adult patients with heart failure and will be performed at approximately 2 study sites in the United Kingdom.