Hello! Thank you for asking on HCM! I would explain that dealing with fast heart beats, includes a comprehensive investigation to first exclude any possible arrhythmias, and if only sinus tachycardia is the only evidence, then to find the exact reason, why this is happening? So, if after a careful physical exam by your doctor, coupled wit ha resting ECG and an ambulatory ECG monitoring, possible arrhythmias are exclude, then we have to deal with sinus tachycardia. To find possible reasons of sinus tachycardia, after excluding structural heart abnormalities by a cardiac ultrasound, you need to perform several blood tests, like complete blood count (to exclude anemia, inflammation, etc), thyroid hormone levels (to exclude increased thyroid function), routine liver and renal function tests, blood electrolytes, and to look for possble external triggering factors, like excess smoking contact, caffeine tea, etc if no identifiable causes could be found, then anxiety bouts, or panic attacks should be ruled our carefully by a comprehensive medical interview. Hope to have been helpful to you. Greetings! Dr. Iliri