Need expert help here. what are beta blockers mainly indicated for?

Htn : High blood pressure, high heart rate, palpitations. These are the major indications.

CAD, CHF ; migraines: In addition to what dr. Kasasbeh mentioned, beta blockers are offered to those who've suffered a heart attack and/or heart failure regardless of their blood pressure. Obviously, we don't want their BP to drop too low such that they pass out, but studies show that judicious use of beta blockers can prevent bad outcomes in these conditions. Some are also used to prevent migraine headaches.