Hi, Thanks for writing in to us. Chemotherapy is a life saving treatment and is targeted to eliminating cancer or controlling the progress of disease in a patient with cancer. To provide chemotherapy, a patient should be fit enough medically to withstand the stress associated with the treatment. Having a heart problem should be carefully analyzed. Heart problems might be due to coronary artery disease, valvular heart disease or rhythm disorders. Some of the chemotherapy drugs are cardiotoxic and therefore such medicines might be avoided for your husband. Please have a detailed discussion with your doctor on this subject. The diagnosis changing from mesothelioma to any other malignant lesion requires another biopsy confirmation. Cancer should not be under treated or treated with wrong set of medicines if it is known that the patient has a particular cancer. Your doctors will take care to confirm the tissue diagnosis before suggesting the right plan of chemotherapy. Starting chemotherapy at a low dose might be beneficial in guiding treatment. Please do not worry.