General cardiologists diagnose and treat all forms of heart disease, as well as help patients avoid heart problems from occurring or worsening. They may use various types of tests, including electrocardiograms (EKG), echocardiograms, computed tomography (CT) scans, and nuclear imaging tests.
Invasive and interventional cardiologists perform highly advanced diagnoses and treatments in a cardiac catheterization (cath) lab, using minimally invasive techniques.
Electrophysiologists diagnose and treat patients with heart arrhythmias, by studying or altering the heart's electrical system.
Cardiothoracic surgeons treat diseases of the heart or heart vessels through surgery.