Heart disease refers to a range of conditions that affect the heart and blood vessels, including coronary artery disease (CAD), which is characterized by narrowed or blocked blood vessels leading to reduced blood flow to the heart muscle. Other types of heart diseases include congenital heart defects, heart failure, cardiomyopathies, arrhythmias and heart valve disorders. These conditions can lead to a variety of symptoms such as chest pain, shortness of breath, dizziness or fainting, and may result in serious complications if left untreated.