If your primary care doctor suspects that you might have a serious heart condition, you will be referred to a cardiologist for a more thorough examination. Symptoms like chest pain, dizziness and shortness of breath often call for a cardiologist to perform more in-depth diagnostic testing. Cardiologists treat heart disease, heart failure and cardiac rhythm disturbances. Their specialized training and skills make them the best candidates to decide when and how to perform major procedures like cardiac catheterization, balloon angioplasty and heart surgery.