Millions of patients with high blood pressure and heart failure take a class of drugs known as ACE (angiotensin-converting enzyme) inhibitors. These drugs prevent the body from processing angiotensin II, a hormone that constricts blood vessels. Scientists have shown that another enzyme present in the heart called chymase is also capable of processing angiotensin II. Adding drugs that interfere with chymase to ACE inhibitors significantly boosted recovery of heart function in animals after heart attack, the researchers found.