Angiography Alone is Insufficient to Guide PCI: The Role of Direct Coronary Imaging

Coronary angiography is an invaluable tool for the detection and treatment of the coronary stenoses causing myocardial ischemia. It permits rapid assessment of the entire coronary circulation and can readily detect a localized stenosis. However angiography has serious limitations, as it provides only limited information about the properties of the wall of the artery, thereby underestimating the magnitude of atherosclerotic burden, particularly in earlier stage disease in which positive vascular remodeling may allow maintenance of “normal” lumen caliber despite substantial vascular wall plaque. In the quest to detect vulnerable and frankly unstable lesions, angiography detects only gross plaque ruptures, which comprise only a subset of those coronary lesions that are truly unstable and provides no insight regarding non-ruptured “vulnerable plaques,” the putative substrate for most acute coronary syndromes and many cases of sudden cardiac death. Importantly, angiography also has significant limitations in the precise delineation of coronary flow limitations in intermediate stenosis in the range of 50-70%. Furthermore, performance of PCI with guidance by angiography only is associated with sub-optimal stent expansion or lack of detection of edge complications in 15%-20% of cases, which has been associated with adverse events. This growing recognition of the need for more information about coronary atherosclerosis to inform clinical decisions and procedural performance of PCI has been the primary impetus for the development of novel intra-coronary imaging methods such as IVUS and OCT that facilitate precise determination of optimal vessel length disease and requires stenting, assure optimal stent deployment (expansion and apposition). Numerous studies now provide support for the concept that compared to PCI guided by angiography alone, direct imaging guidance is associated with lesser incidence of stent thrombosis and late stent restenosis.