Dear Madam Thanks for your query. The dull ache, if transient, like a shock, can occur in such patients as a result of shock given by CRT-D device. These shocks may be appropriate or in appropriate which will be decided by pacemaker evaluation. If the dull ache is persistent but is precipitated by exertion , this could be anginal pain which may occur in late stages of DCMP. Persistent dull ache unrelated to exertion can occur due to very severe heart disease or can be non-cardiac. An evaluation by your cardiologist is required and will be helpful. Sincerely Sukhvinder