Cardiology refers to the field of internal medicine that deals with the disorders of the cardiovascular system. It focuses on the diagnosis and treatment of heart-related conditions such as coronary artery disease, heart failure, congenital heart defects, valvular heart disease, and atheroma. High levels of low-density lipoprotein (LDL) cholesterol, obesity, high blood pressure, diabetes, physical inactivity, smoking, poor diet, and exposure to passive smoke are the major risk factors for cardiac diseases and strokes. Echocardiogram (ECHO), electrocardiogram (ECG), ambulatory ECG, and stress test are some of the most common diagnostic tests performed in cardiology. There are a variety of strategies for treating cardiovascular diseases including percutaneous coronary intervention, stenting, coronary artery bypass surgery, and percutaneous transluminal angioplasty. In order to manage heart health, people may also introduce certain lifestyle modifications such as consumption of balanced healthy diet (to lower cholesterol levels and blood pressure), regular exercise, taking prescribed medications, and maintaining a healthy body weight. In this book, using case studies, constant effort has been made to make the understanding of the difficult concepts of cardiology as easy and informative as possible. It is appropriate for students seeking detailed information in this area as well as for experts.