He may exercise aerobically, and with monitoring of his heart rate. If he is 50, his maximal heart rate should be around 115-120 bpm. If he develops symptos or signs of angina or CHF before reaching that target, then he should moderate his efforts. I would advise against heavy lifting, as this can raise blood pressure, and affect LV performance.
He is certainly a candicate for established medical therapies with beta blockers, ace inhibitors, aldosterone blockers and digoxin. He may also need a defibrillator or a special 3 lead pacemaker system. These options, however, are offered on a case by case analysis, and he may not need or benefit from them.
In this age group he should be seeing a CHF specialist which besides offering all of these treatments can start looking into the future and see if he is a candidate for transplant and begin the process before his condition deteriorates.