question: What is the ideal pulse/heartrate to assist in the possible shrinkage of an enlarged heart, please? I am 49 years old, under 9 stone, 5ft 6 and a half inches tall. I have had an overactive thryoid and partical thyroidectomy in 2006 and also anaemia. I had a chest infection with SOB in 2009 and a very bad chest infection this year May-June 2011. SOB worse, xray enlarged heart and possible dilated cardiomyopathy & left bundle block. Both ventricles affected and left atrial. No evident coronary disease. Drugs made symptoms worse.