 Measurement of coronary flow reserve CFR using the Volcano FloWire can assess physiological changes in the distal vascular bed. The primary endpoint of this study will evaluate coronary flow reserve after successful treatment of severely calcified coronary lesions using OAS and stent deployment. The secondary endpoint will measure the occurrence of post-procedural Major Adverse Cardiac Events MACE, including Cardiac death, acute myocardial infarction Q wave or non-Q wave, or target vessel revascularization. 