Fractional flow reserve (FFR) is a test that can be performed at the time of heart catheterization. It measures the change in pressure across a narrowing in the heart artery during high flow situation, and provides reliable information about the functional severity of the narrowing. FFR measurements accurately predict whether a stent is needed, and is considered an excellent test before placement of stents to treat narrowed heart arteries. However, FFR is not used in every case because of the extra time needed and the associated device costs. Cardiac Services BC (an agency of Provincial Health Services Authority) is sponsoring this study to find out if FFR should be used in most cases (routine), rather than the current selective approach.