After 12 days of antibiotics treatment, the heart specialist suggested that it is time to do an operation – to remove the alien object in my heart and repair / replace the valve.
Started from 8:30 in the morning and the operation was done successfully 5 hours later.
Turned out the alien object is only a minor issue and the specialists managed to repair the valve instead of replacing it (which is a worse option).
3 days later, I can walk around the ward already.
Really a magical operation.