Metoprolol tartrate (me TOE proe lole) treats high blood pressure. It also prevents chest pain (angina) or further damage after a heart attack. It works by lowering your blood pressure and heart rate, making it easier for your heart to pump blood to the rest of your body. It belongs to a group of medications called beta blockers. This medicine may be used for other purposes; ask your health care provider or pharmacist if you have questions.