Heart attack occurs when blood is reduced or completely block in the coronary arteries of heart. This may occurs by cholesterol and with eating fat or by eating other substances which contain fat that cause a making clot in coronary arteries. it is commonly known as atherosclerosis which means hardening of arteries. Often a plaque can be thick with the passage of time which stop the supply of blood.
Causes:

Smoking:
Smoking increases the risk of heart attack. When you smoke it disturbs your heart and blood vessels. It increases the rate of narrowing of arteries. Tobacco does not cause heart attack but it speeds up the blood clotting in the coronary arteries.
Hypertension:
High blood pressure increases the pressure of blood on the walls of arteries. When blood pressure is so high and is not controlled it damages the body organs.
Normal blood pressure in Children is <90th centile from 1 to 13 age. From 13 to 17 year children Normal Blood Pressure is <80 to <120 mm Hg. Uncontrolled High blood pressure can leads to:
1) Heart Attack
2) Stroke
Obesity:
Eating too much fat can lead to obesity and it produce plaques in arteries it results in the formation of multiple deposits called plaques within arteries. Plaques can form blood clots called thrombus within arteries. If a thrombus dislodges and becomes free floating, it is called an embolus.
Stress:
In psychology, Stress is an emotional strain and pressure on brain. Risk of attacks and arteries are narrowed by the Emotional Stress. Raise of risk stroke can be raise and change of clot and narrowed by the ongoing stress.
Diabetes:
Diabetes increases the risk of heart attack. High level of sugar can doubled the risk of CHD.
Symptoms:
Angina pectoris:

Angina pectoris is means chest pain. It is not severe as heart attack. The pain may occur in heart and often in left arm and shoulder it is a warning signs that blood supply to heart muscles is not sufficient but shortage is not enough to cause tissue death. Severe chest pain is the most common symptom of Mayo Cardial Infraction and may be in the form of sensation of tightness pressure and squeezing pain radiates most often to left arm but may also radiates to lower jaw neck right arm and back. Loss of consciousness and even sudden death can occur in mayo Cardial infraction. Preventions:
Immediate treatment for suspected acute myocardial infarction includes oxygen supply, aspirin, and sublingual tablet of glycerol tri Nitrate.

Surgeries:

Angioplasty (mechanical widening of a narrowed or totally obstructed blood vessel) or Bypass surgery (surgery in which arteries or veins from elsewhere in the patient’s body are grafted to the coronary arteries to improve blood supply to heart muscles).
World Health Day:
World Heart Day is held on 28th September every year throughout the world. Its objective is to help people better understand their personal risks of cardiovascular disorders.