The mention of heart issues (either pre-existing or side effects that develop with treatment) tipped me off to let members know about a cancer specialty called cardio-oncology. This may be available where you receive treatment.

Here's info about the program at Mayo Clinic that offers expertise in addressing heart problems potential or current issues. The Cardio-Oncology Clinic (https://www.mayoclinic.org/departments-centers/cardio-oncology-clinic/overview/ovc-20442193) evaluates people prior to cancer treatment and patients who have experienced side effects due their treatment.