Succinate is the short duration form, while tartrate is the 'slow release form'. Might you do better on the tartrate...assuming it is not contraindicated for a very good reason? Can you reduce the dosage?
A great many people, myself included, do develop moderate-severe bradycardia after a certain dose is achieved. Normally, the physician responsible will advise a reduction in the amount taken if this happens.
BTW, I always took metoprolol on an empty stomach. I can't say it affected me adversely until my daily intake exceeded 125 mg/day.