The CARVTOP-ICD Trial is a national study comparing two guideline-approved treatments for heart failure. Carvedilol and metoprolol succinate are heart medications that belong to a group called beta-blockers. These medicines help protect the heart by making it work more slowly and with less strain. Your body releases stress hormones (like adrenaline) that make your heartbeat faster and harder. In patients with heart failure this extra stress can damage the heart, causing abnormal heart rhythms and can increase the need for hospitalization due to fluid buildup in the body. Both carvedilol and metoprolol succinate are standard, guideline-approved treatments for heart failure. Doctors use both every day, and both have been shown help people live longer and stay out of the hospital. However, until now these 2 medications have not been compared to each other to determine if one may be better than the other.