Several potential explanations have been proposed for these conflicting views. Revascularization procedures may not alter the natural history of multicentric plaque rupture determined by complex arterial vascular biology. CAD exists diffusely in addition to segmental stenosis, so that localized mechanical intervention may fail to alter long-term disease progression or outcome. Additionally, anatomic severity on coronary angiography may not reflect the physiologic severity that directly determines ischemia, left ventricular function, and prognosis. Invasive physiologic criteria such as fractional flow reserve (FFR) can be utilized during invasive angiography to further educate decision making about whether to perform PCI, however FFR is performed in only 6% of percutaneous coronary interventions (PCI) in the United States. Consequently, percent stenosis on coronary angiography remains the main determinant when deciding to proceed with PCI.