The COMET trial is an observational, cross-sectional study aimed at comparing the incidence of coronary microvascular dysfunction (CMD) in patients with stable angina who have a history of severe COVID-19 infection requiring mechanical ventilation (Group A) to those without a history of COVID-19 (Group B). A total of 102 participants will be recruited, with 51 patients in each group.

Data will be collected on participants' demographic information, medical history, and COVID-19 infection history (confirmed by PCR test). CMD measurement will be performed using a pressure-temperature wire to assess the coronary flow reserve and index of microcirculatory resistance. In addition, information on participants' current medications will be gathered. The study will employ statistical analysis tools to compare CMD incidence between the two groups and assess the impact of various factors such as age and sex on CMD incidence. The results of the COMET trial will provide valuable insights into the effects of severe COVID-19 infection on CMD in patients with stable angina.

The COMET trial is an observational, cross-sectional study that aims to compare the incidence of coronary microvascular dysfunction (CMD) in patients with stable angina who have a history of severe COVID-19 infection requiring mechanical ventilation (Group A) to those without a history of COVID-19 (Group B). A total of 102 participants will be recruited, with 28 patients in each group.

The study will be conducted at two university hospitals: Seamen's Branch, Department of Cardiology, Klaipeda University Hospital, Klaipeda, Lithuania, and the Hospital of Lithuanian University of Health Sciences Kaunas clinics, Kaunas, Lithuania. The anticipated study duration is 6 months.

CMD measurement will involve assessing coronary flow reserve (CFR), fractional flow reserve (FFR), and index of microvascular resistance (IMR) using the CoroFlow system (Coroventis Research AB, Uppsala, Sweden). After diagnostic coronary angiography is performed and no significant visible lesion is identified, nitroglycerin will be administered through the intracoronary catheter. A calibrated coronary physiology wire (Pressure Wire X; Abbott Vascular, Santa Clara, CA, USA) will be equalized to the guide catheter pressure at the sinus of the aorta and advanced to the distal two-thirds of the left anterior descending artery. Three milliliters of normal saline will be administered through the guiding catheter in triplicates during rest and during maximal hyperemia, which will be induced by injecting intracoronary adenosine.

Data analysis will be performed using appropriate statistical tests, such as the chi-squared test or Fisher's exact test for categorical data and the independent-samples t-test or Mann-Whitney U test for continuous data, as appropriate. Multivariable regression analysis will be used to assess the impact of various factors, such as age and sex, on CMD incidence.

The primary outcome measure for this study will be the incidence of CMD in both groups, as measured by both coronary flow reserve (CFR) and index of microvascular resistance (IMR) using the pressure-temperature wire. A potential secondary outcome measure could be the relationship between CMD severity and the severity of the patients' COVID-19 infection.

Safety monitoring and adverse event reporting procedures will be in place to ensure patient safety. All adverse events occurring during the study will be recorded and reported to the appropriate institutional review boards and regulatory authorities. Serious adverse events will be reported to the principal investigator within 24 hours of the study team's awareness of the event. The study team will regularly review adverse event data to assess patient safety and make any necessary modifications to the study protocol.

The results of the COMET trial will provide valuable insights into the effects of severe COVID-19 infection on CMD in patients with stable angina.

Here's a detailed outline of the eligibility criteria, including inclusion, exclusion, and withdrawal criteria for the COMET trial. Please review and let me know if you need any further clarification or have additional information to provide.

Inclusion Criteria:

1. Patients with a clinical diagnosis of stable angina, consulted by a cardiovascular consultant and referred to undergo diagnostic coronary angiography.
2. Patients who are able to provide informed consent.
3. For Group A: Patients with a history of severe COVID-19 infection requiring mechanical ventilation, confirmed by a PCR test.
4. For Group B: Patients without a history of COVID-19 infection.

Exclusion Criteria:

1. Patients with unstable angina or acute coronary syndrome.
2. Patients with a history of myocardial infarction, percutaneous coronary intervention, or coronary artery bypass graft surgery.
3. Patients with known structural heart disease or valvular heart disease.
4. Patients who are unable to undergo intracoronary pressure-temperature wire measurement of CMD due to contraindications or other medical reasons.

Withdrawal Criteria:

1. Withdrawal of informed consent by the participant at any time during the study.
2. Development of an unstable medical condition or complication that prevents the participant from completing the study or makes it unsafe for them to continue.
3. Identification of exclusion criteria after enrollment that should have precluded the participant's inclusion in the study.
4. Non-compliance with study procedures or protocol deviations that may affect the validity of the study results.

The study population for the COMET trial consists of adult patients (aged 40 -80 years) with a clinical diagnosis of stable angina.

The study population will be divided into two groups:

Group A: Patients with a history of severe COVID-19 infection requiring mechanical ventilation, confirmed by a polymerase chain reaction test. This group represents individuals with stable angina who have experienced a severe COVID-19 infection and later on developed stable angina symptoms.

Group B: Patients without a history of COVID-19 infection. This group serves as a comparison group to assess the potential differences in CMD incidence among patients with stable angina who have not been affected by COVID-19 infection.