A person with any type of heart disease should definitely check with their doctor before using a hot tub, but the safety of it really depends on the type of heart disease and the person’s current condition—ie. whether disease is stable. High temperatures dilate blood vessels and elevate heart rate which can put additional strain on an already weakened heart. But studies have shown patients with stable coronary artery disease who exercise regularly can enjoy a 15 minute hot tub dip if the temperature is 40 degrees or less. Patients with unstable heart disease, heart failure, and aortic stenosis should not use hot tubs.