Answer:
a. His heart is protected by numerous collaterals
Explanation:
Coronary collaterals or natural bypasses are the anatomical connections between portions of same coronary artery and between different coronary arteries.
As in the given scenario, the patient is a bicyclist butubsequent cardiac catheterization and angiogram reveal severe occlusion of one of his coronary arteries that means the exercise (byccling) have seen to lead the growth and development of collateral coronary flow when blockages prevent original vessel from opening.
As a result, these collateral vessels can supply blood flow to the ischemic regions caused by occlusion of the arteries (the reason why he denies having anginal symptoms) .Collateral circulation provides alternate routes of blood flow to the heart in cases when heart isn't getting the blood supply it needs.