Hello! Welcome on HCM! I understand your concern and would explain that such a clinical symptomatology could be likely related to a possible rhythm disturbance which needs to be further investigated. Frequently, a cardiac arrhythmia may be caused by a certain structural heart disorder, but not rarely it may be triggered by an extra-cardiac abnormality (such as a hormone imbalance, electrolytes level disorder, another functional organ dysfunction, etc.). Considering the fact your husband has a long history of heart murmur, it is necessary performing a cardiac ultrasound in order to exclude any possible valvular dysfunction, congenital abnormality, cardiomyopathy,etc.) An important point is to perform a comprehensive medical check up including besides a careful physical exam additional lab tests as follows: - complete blood count, - resting ECG, - chest X ray study, - thyroid hormones level, - liver and renal function tests, - blood electrolytes level, - fasting blood glucose level, - ambulatory 24 to 48 hour ECG monitoring (Holter) You should discuss with his attending doctor on the above mentioned issues. Hope to have been helpful to you! Kind regards, Dr. Iliri