Hello. Thank you for your question and welcome to HCM. I understand your concern. When heart beats fast and produces forceful, regular beats, it is indicative of a probable anxiety attack and/or panic attack. All types of anxieties have one thing in common: a spike of adrenalin levels in the system, which has a lot of effects on the human organism, with increasing the heart rate and the blood pressure, among others. As a consequence, shortness of breath and the sense of fear to what is happening to me? am I going to die? , may arise. Therefore, judging also by your young age, my opinion is that this was an anxiety attack. Adding to this, the probability of anxiety attack is raised also by the fact that you felt well after taking the alprazolam. Benzodiazepines are a good class of drugs which control and prevent anxiety attacks, but they tend to create dependency after a short time of usage. My opinion is that another old (but gold) drug from the beta-blockers has anxiety-relieving properties and, also, heart rat-lowering properties: propranolol. You can discuss with your cardiologist about the dosage and frequency of taking this drug. I hope I was helpful. Take care. Kind regards, Dr. Meriton