Coronary artery disease is caused by a buildup of fatty deposits in the arteries that supply the heart. Partial blockages can cause angina pain, while complete blockages result in a myocardial infarction. Major risk factors include age, male sex, family history, hypertension, smoking, diabetes, obesity, and physical inactivity. Diagnosis involves tests like ECG, cardiac enzymes, and imaging to determine the extent of blockages. Treatment focuses on pain relief, lifestyle changes, medications, and procedures like angioplasty or bypass surgery to restore blood flow.