Carol,   Thanks for your question.   The answer to your question is yes.  Any extremes in temperature can cause problems in heart disease.  Cold temperatures can cause angina - chest pain caused by coronary artery disease.  High temperatures can cause several changes such as faster heart rates and dilatation of blood vessels everywhere in the body, both of which can adversely affect the heart, especially in congestive heart failure.    I suggest hot tubs, and their usual high temperatures, be avoided by anyone with significant heart disease.  This certainly includes people with congestive heart failure.   Best wishes.   Martin Cane, M.D.