Inclusion Criteria:  Age 18 years or greater Willing and able to give informed consent. The patients must be able to comply with study procedures Undergoing clinically-indicated coronary angiography and OCT  Exclusion Criteria  Baseline electrocardiographic changes hindering interpretation (such as left bundle-branch block, and >1 mm ST segment depression) Emergency cardiac catheterization (for example in patients with ST-segment elevation acute myocardial infarction) Inability to provide symptomatic assessment Known allergy to contrast