My Boyfriend Has Had 2 Heart Attacks, 3 Stents And

My boyfriend has had 2 heart attacks, 3 stents and a defibrillator/pacemaker and a lead revision all in the last 5 months. His heart function is at 35% as a result of the first heart attack. His blood pressure is normally on the low side. He is unable to take beta blockers because it dropped his blood pressure dangerously low. He falls asleep shortly after eating. It doesn't seem to matter what he eats. He is 5' 7" and around 180 lbs. What is causing the need to sleep after eating?