Demand for cardiologists remains strong, driven by an aging population and the increase of chronic illness including heart disease. Educational barriers to entry for cardiology remain high. A bachelor's degree with pre-medical coursework in biology, mathematics and chemistry is required. Following completion, a medical degree (MD) and several years of post-graduate supervised residency experience in a hospital or clinic is required. Some cardiologists who intend to pursue cardiology research choose to earn joint MD-PhD degrees, which require the additional completion of a dissertation.