Cardiac arrest is a serious heart condition. It is an abrupt loss of blood flow to the heart. It is triggered by an electrical malfunction in the heart which causes arrhythmia. With its pumping action disrupted, the heart cannot pump blood to brain, lungs and the person lose consciousness and the pulse declines. If the victim does not receive treatment the patient dies within minutes. The common cause of cardiac arrest is abnormal heart beat called ventricular fibrillation. Other causes of cardiac arrest are heart attack, cardiomyopathy, congenital heart disease, heart valve disease, acute myocarditis. The symptoms of cardiac arrest include unconsciousness, unresponsiveness, chest pain, shortness in breath, nausea etc. Coronary artery disease is the main cause of cardiac arrest. In cardiac arrest heart beat stops which may sometimes result in person death. Diagnostic tests for cardiac arrest are electrocardiogram, echocardiography, MUGA test, cardiac MRI, cardiac catheterization Treatment includes drugs, implanted medical devices. In case of medical emergency automated external defibrillator, immediate CPR is used.