A great number of heart attacks materialize as the result of Atherosclerosis. Atherosclerosis is a progressive build up of plaque in the arterial walls. As time passes, this build up will cause hardening of the arterial walls which will consequently decrease the room available for blood flow through the arteries. Therefore, the blood flow will be limited as the disease progresses. This will then lead to the lowered functioning of the organ that is affected and the circulatory system in general. If atherosclerosis is present in the legs the reduction of blood flow will likely cause leg pains when walking or exercising, leg ulcers, or an obvious decline in the ability for wounds to heal in that region. If atherosclerosis develops in the arteries that supply blood to the brain this may cause vascular dementia which is mental deterioration as a result of prolonged death of the brain tissue over a period of years. In some instances it may result in a stroke.

Atherosclerosis may be asymptomatic for several years for some persons with this condition. The disease can commence as early as the teenage/adolescent years, but the corresponding symptoms or health issues normally do not present themselves until later in adulthood when the constriction of the arteries have significantly intensified. Certain risk factors such as smoking cigarettes, high blood pressure, elevated cholesterol, and diabetes mellitus can worsen atherosclerosis and prompt the symptoms to be exhibited sooner. Complications may develop, especially in individuals who have a family history of developing atherosclerosis earlier in life.
Coronary atherosclerosis or as it is also known coronary artery disease pertains to atherosclerosis that is present within the arteries of the heart which results in the hardening and narrowing of these arteries. Diseases that are induced by the lessened blood supply to the cardiac muscle from coronary atherosclerosis are termed coronary heart diseases or CHD. Coronary heart diseases will encompass heart attacks, heart failure as a result of the deterioration of the heart muscle, cardiac arrest, chest pain or angina, and irregular heart rhythms.

At times, the surface of cholesterol plaque in the coronary artery may burst, and create a blood clot. The clot will hinder the flow of blood entering the artery and cause an imminent heart attack. The exact reason for the unforeseen rupture that becomes a clot has not been identified. Some probable factors will include cigarette smoking or other types of nicotine exposure, hypertension, elevated LDL cholesterol levels, higher than normal levels of blood catecholamines (adrenaline), among other risk factors.

Heart muscle will eventually die during the course of a heart attack. This muscle death will be irreversible, if the blood flow is not restored immediately.

Even though heart attacks may materialize at any time of day, most heart attacks will occur between the hours of 4:00 A.M. and 10:00 A.M. This is thought to be as a result of the higher blood levels of adrenaline emitted from the adrenal glands at this particular time during the morning. The rising adrenaline levels are typically accompanied by the rupture of cholesterol plaques.
About 50% of patients who experience heart attacks develop some warning signs which include angina from exertion or from resting, before they are affected by a heart attack. Sadly, these symptoms may be too insubstantial to be thought of as life threatening.

Subsequently, it is important to receive medical attention for any of the following symptoms that may signal a heart condition including chest pain most commonly angina pectoris, difficulty breathing, extreme tiredness, jaw pain and upper back pain. Immediate treatment of a heart attack will greatly improve the prognosis.