What is Diovan (Valsartan)? Valsartan is used to treat high blood pressure and heart failure. It is also used to improve the chance of living longer after a heart attack. In people with heart failure, it may also lower the chance of having to go to the hospital for heart failure. Valsartan belongs to a class of drugs called angiotensin receptor blockers (ARBs). It works by relaxing blood vessels so that blood can flow more easily. Lowering high blood pressure helps prevent strokes, heart attacks, and kidney problems.