Evaluation of the Efficacy and Safety of Tirzepatide, a Dual GLP-1/GIP Agonist, on Functional Capacity in Reduced Ejection Fraction Heart Failure Patients With Obesity

This is a phase 3, randomized, double-blind (participant, care provider, investigator, and outcomes assessor blinded), placebo-controlled, parallel- group clinical trial evaluating the efficacy and safety of tirzepatide, a dual glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) receptor agonist, in participants with heart failure with reduced ejection fraction (HFrEF) and obesity. Eligible participants are adults aged 18 years or older with HFrEF (left ventricular ejection fraction ≤40% on echocardiography within the prior 3 months), a body mass index ≥27 kg/m² with at least one obesity-related comorbidity (hypertension, diabetes, or dyslipidemia), and stable guideline-directed heart failure therapy for at least 4 weeks prior to enrollment. Key exclusion criteria include recent acute heart failure decompensation or hospitalization, uncontrolled blood pressure, advanced kidney disease (eGFR \<30 mL/min/1.73m²), significant hepatic impairment, active pancreatitis, personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia type 2, and pregnancy or breastfeeding. A total of 60 participants will be randomized 1:1 using a computer-generated block randomization schedule (block size of 4) to receive either tirzepatide or matching placebo, both administered as weekly subcutaneous injections. Study drug is initiated at 2.5 mg once weekly and titrated every 4 weeks, as tolerated, up to a maximum of 10 mg once weekly, continuing through month 6. The placebo pen is identical in appearance, packaging, and dosing schedule to maintain blinding. The primary outcome is change in 6-minute walk distance from baseline to 6 months. Secondary outcomes include change in New York Heart Association functional class, Kansas City Cardiomyopathy Questionnaire quality-of-life score, body mass index, ejection fraction, pulmonary artery pressure, and metabolic parameters (fasting glucose, glycated hemoglobin, lipid panel), measured at baseline and at months 2, 4, and 6. Safety outcomes include gastrointestinal adverse events, injection-site reactions, hypoglycemia, pancreatitis, gallbladder events, and changes in liver enzymes, amylase, and lipase. An exploratory outcome evaluates shared molecular and genetic pathways linking obesity and HFrEF using peripheral blood RNA analysis via quantitative PCR or next-generation sequencing. The study is being conducted at seven sites in Tehran, Iran, including Masih Daneshvari Hospital, Shahid Rajaei Cardiovascular Medical and Research Center, Rasoul Akram Hospital, Tehran Heart Center, Firoozgar Hospital, Ayatollah Taleghani Hospital, and Imam Khomeini Hospital Complex.