When atheroscerosis progresses the plaque begins to occlude the lumen of the coronary artery.The contractility of the artery is also lost.When about 75% of the lumen is occluded,the coronary artery is unable to supply enough blood to the heart when its needs are raised .eg. while performing strenous work.
Symptoms will appear.The symptoms usually last for about 1- 10 minutes and is relieved by rest or sublingual nitroglycerine.The symptoms are:-

Pain,pressure or discomfort at mid chest
The chest discomfort may radiate to the upper part of the body, arms,neck or jaw
These symptoms usually appear during or immediately after some physical activity or while experiencing sudden emotional tension.
breathlessness on moderate exertion

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