The American Heart Association grew out of a set of smaller precursor groups. The primary precursor was the Association for the Prevention and Relief of Heart Disease, formed in New York City in 1915, to study whether patients with heart disease could safely return to work. Several similar organizations formed or evolved in Boston, Philadelphia, and Chicago in the 1920s. Recognizing the need for a national organization to share research and promote findings, the American Heart Association was formed in 1924 by six cardiologists representing several of these precursor groups.