The goal of this clinical trial is to evaluate whether short-term dietary interventions can improve cardiometabolic risk factors in patients after myocardial infarction. The study includes adult patients following myocardial infarction.

The main questions it aims to answer are:

• Does adherence to an ESC-recommended diet lead to improvements in lipid profile and body composition compared with no dietary intervention?
• Does a plant-based (vegan) diet lead to similar or greater improvements in cardiometabolic parameters compared with the control group? Researchers will compare the ESC diet group and the plant-based diet group with a control group to assess their effects on body mass index, lipid profile, and inflammatory markers.

Participants will:

• be assigned to one of three groups (ESC diet, plant-based diet, or control),
• receive dietary counselling according to their assigned group (intervention groups),
• follow the assigned dietary pattern for 3 months,
• undergo baseline and follow-up clinical and laboratory assessments, including anthropometric measurements and blood sampling.

This was a single-center, three-arm, controlled, partially randomized interventional pilot study designed to evaluate the feasibility and potential effects of dietary modification in the secondary prevention of myocardial infarction over a three-month period. Participants were recruited between January 2022 and December 2025. The study duration was three months.

Participants who agreed to change their dietary habits were randomized in a 1:1 ratio into two intervention groups using stratified block randomization according to diabetes mellitus status and smoking status. Group A followed a diet based on the recommendations of the European Society of Cardiology (ESC), while Group B adopted a strictly plant-based (vegan) diet.

Patients who declined dietary modification but agreed to undergo study assessments were included as a parallel, non-intervention control group (Group C), based on patient preference.

All participants underwent clinical and laboratory assessments at baseline and at three months, including body composition analysis using bioimpedance (InBody). In the intervention groups, additional scheduled visits were conducted at monthly intervals during the three-month period. At these visits, participants received nutritional counseling from a registered dietitian and completed a three-day dietary record to assess dietary intake and adherence. Participants were additionally allowed to contact the dietitian or the study physician outside the scheduled visits if needed.

Laboratory analyses included lipid profile (total cholesterol, LDL cholesterol, HDL cholesterol, lipoprotein(a), triglycerides), glycemic parameters (fasting blood glucose, glycated hemoglobin HbA1c), inflammatory markers (high-sensitivity C-reactive protein (hsCRP) and interleukin-6 (IL-6)), vitamin B12, vitamin D, iron metabolism, complete blood count, and basic biochemical parameters.

Patient recruitment was conducted in collaboration with the coronary care unit of St. Anne's University Hospital Brno (FNUSA). Nutritional counselling was delivered by trained Master's degree nutrition therapy students from the Faculty of Medicine, Masaryk University.

Inclusion Criteria:

• Myocardial Infarction First

Exclusion Criteria:

• Myocardial Infarction Second
• Age under 18

This is a pilot academic study; there is no need to share the IPD with other researchers.