25 yo, otherwise healthy college student Male, 146 lbs, 5' 11". Family Hx positive for cardiovascular disease and diabetes. No significant past medical Hx. Occasional use of alcohol and caffeine. No smoking or recreational drug use. No current medications.
Recently visited cardiologist for abnormally high basal heart rate, ~97 bpm with arrhythmia. Blood pressure within normal range. MD suggested that I start on metoprolol 25 mg STAT. He did ECG, and it was abnormal. But he didn't confirm any diagnosis. I have another appointment after 2 weeks for ecocardiogram, and most likely MRI.
What is the most likely diagnosis? I would appreciate any of the comments.