The goal of this clinical trial is to determine the effect of ozone treatment in heart failurte with reduced ejection fraction. The main questions it aims to answer are:

Does ozone treatment have beneficial effects in heart failure patients? What medical problems do heart failure patients have when taking ozone treatment? Researchers will compare ozone treatment in patients with heart failure to ozone treatment in patients with no heart failure (control group) as well as before and after the ozone treatment in patients with heart failure to see if ozone works to treat heart failure.

Participants will:

Give blood samples Take 6-minute walk test Be perfomed Echocardiography with CFR (Coronary Flow Reserve) Take drug ABC or a placebo every day for 4 months Visit the clinic twice a week for ozone treatment for 2 months Give blood samples (after the ozone treatment) Take 6-minute walk test (after the ozone treatment) Be perfomed Echocardiography with CFR (Coronary Flow Reserve) (after the ozone treatment)

Patients who were previously scheduled for ozone therapy at the ozone therapy clinic of Medicana International Hospital Istanbul for another indication that did not affect the endothelial function of coronary arteries were included in the study. Patients with diseases or conditions that may affect endothelial function such as diabetes mellitus, chronic renal failure, thyroid or liver dysfunction, inflammatory diseases or smoking were excluded. Thirty-eight patients with non-ischemic cardiomyopathy who underwent coronary angiography in the Cardiology Department of Medicana International Hospital Istanbul and had less than 50% stenosis and less than 40% ejection fraction (EF) on transthoracic echocardiography were included in the study. All participants were taking beta-blockers, ACEi and mineralocorticoid receptor antagonists for the treatment of heart failure. A control group of 22 people with similar age, sex and demographic properties and no chronic disease has included to the study.

After the patients were enrolled in the study, blood samples were taken and 6-minute walk test, CFR measurement and transthoracic echocardiography were performed. They were then sent for ozone therapy. Two months later, after ozone therapy, blood samples were taken and 6-minute walk test, CFR measurement and transthoracic echocardiography were performed again.

Inclusion Criteria:

• Previosuly known coronary angiography with less than % 50 stenosis
• Echocardiography with ejection fraction of less than % 40
• Patients with previosly planned for ozone treatment for non-chronic disease or conditions

Exclusion Criteria:

• Known chronic diseases or conditions that effect endothelial functions.
• Previosly had acute coronary syndrome or stent implantation or any coronary intervention.
• Smokers

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request after the manuscript published

Data of this study will be upload to clinicaltrials.gov after publication of the study