What Causes Stomach Bloating After Suffering From Heart Attack?

My husband is feeling stomach bloating, almost ever day or every other day, following heart attack and stent procedure three weeks ago. No shortness of breath. He has told a local cardiologist about the bloating, who said probably just normal post-op recovery. But it is worrisome to my husband, and uncomfortable. He is 61, slightly overweight, works out regularly (prior to stent surgery, cardio and weight lifting), post-op he is now up to walking 2 miles each morning, and has kept a modest diet of lean meat and veg, not as much appetite as before, which he welcomes. But the bloating worries him, b/c that was the feeling he had during his heart attack, but this is not as severe. Suggestions?