I take toprol xl 100 mg 1 x per day for Idiopathic Hypertrophic Subaortic Stenosis. I also have an ICD which was placed in 05/2002 and I have had 2 subsequent lead changes (05/02) and (01/09) and a generator change (01/2009). I know that I am ideally supposed to avoid large amounts of caffeine , however, I drink on average 2 Monster Energy Drinks per day. I am starting P90X soon and several friends take Jack3D for more energy during workouts. I was wondering if I should be fine taking Jack3D (AS INSTRUCTED at 1 scoop). I have read reviews that referece the increased heart rate , however, I don t know that the increase would be sufficient to involve my ICD. Any feedback would be greatly appreciated. Thanks, Todd