This clinical trial is studying people who have had a heart transplantation and are taking acetylsalicylic acid (aspirin) as Thrombo ASS 100 mg-Filmtabletten. The purpose of the study is to check how often aspirin resistance happens in this group. Aspirin resistance means that the medicine may not work as expected to help prevent blood clots.

In the study, blood testing is done during a follow-up visit after the transplant. The tests are used to see how the platelets, which are small blood cells that help blood clot, respond to aspirin. The study looks at patients about 12 to 18 months after heart transplantation and compares the blood test results with health details such as age, sex, diabetes, high blood pressure, smoking, past rejection episodes, infections, and cholesterol levels.

The study does not use a new treatment. It focuses on testing the effect of the aspirin already being taken after heart transplantation. The results are intended to improve understanding of how well aspirin works in this setting.