The most serious consequence of coronary artery disease is sudden death. When the heart stops, emergency resuscitation (CPR) is required. It is estimated that this devastating situation occurs in as many as 1 out of every 3 patients who are unaware that they have coronary artery disease.
In sudden death, a plaque may rupture suddenly (like the eruption of a pimple), which then triggers the release of clotting factors in the blood that cause a clot to form in a major artery. This blockage of the artery prevents crucial oxygen from reaching the heart, which can injure a large area of heart muscle. In this situation the person may die from what is called cardiogenic shock.
At other times, the blocked artery can cause a serious heart irregularity in the rhythm of the heartbeat (an arrhythmia), and if the patient is not rescued or does not receive resuscitation (CPR) then that person will die. Another consequence of narrowing or blockage of a coronary artery is a heart attack. A heart attack results from actual damage to the heart muscle, similar to a bruise. This damage causes severe pain and the release of chemicals or enzymes into the blood from the damaged heart muscle. Your doctor can measure the amount of these released enzymes (CPK or troponin) to determine the size or degree of heart muscle injury.
If the buildup or narrowing in the coronary arteries occurs more gradually, then a person may feel a warning that they have heart disease. This warning is usually in the form of chest pain (angina pectoris). This is a signal or symptom that the oxygen flow to the heart muscle is reduced, or that the heart muscle is not getting enough oxygen at that moment.