Hello! Welcome and thank you for asking on HCM! Regarding your concern I would explain that your symptoms seem to be related to anxiety or a panic attack. Did you feel other symptoms like difficulty breathing, shortness of breath, fainting, etc.? Anyway a cardiac arrhythmia can not be excluded even with a normal ECG. I recommend consulting with your attending physician for a careful physical examination and some tests : -a cardiac ultrasound to examine your cardiac function -an ambulatory 24-48 hours ECG monitoring to examine your heart rhythm trends during the day and exclude possible arrhythmia -blood lab tests (complete blood count, blood electrolytes, thyroid hormone levels, fasting glucose, kidney and liver function tests, etc.). I recommend you discussing with your doctor on the above tests. If all the above mentioned tests result normal, the main cause of your symptoms would be just anxiety. Hope to have been helpful! Feel free to ask me directly at any time for any other uncertainties. Best regards! Dr. Iliri