Standardizing Definition and Methodology for Complete Revascularization

Ziad Ali, MD, discusses his recently published paper “Standardizing the Definition and Analysis Methodology for Complete Coronary Artery Revascularization” published in Journal of the American Heart Association (JAHA). His aim in this paper is provide a systematic method to assess complete revascularization after percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG) for clinical trials as well as practicing interventionalists. Dr. Ali is the director of the De Matteis Cardiovascular Institute, St. Francis Hospital and Heart Center in Roslyn, NY.

Dr. Ali defines both ‘anatomical’ and ‘ischemic’ revascularization. “Anatomical really is an assessment of the burden of atherosclerosis, not the impact of that atherosclerosis on the myocardium,” he explains. He and his colleagues define anatomic using a percent diameter stenosis consistent with previous literature where there is flow limitation on 50% stenosis. They also state that either a quantitative coronary angiography (QCA) diameter stenosis >50% or visual estimation (VE) diameter stenosis of 50% is considered an ‘anatomical lesion.’

Dr. Ali explains Figure 1 from his paper, which defines anatomic revascularization assessment. An anatomically significant lesion is a lesion with a residual diameter stenosis of ≤30% after treatment, in keeping with the ACC guidelines for standardization of success for a PCI. “What we do is we add up all the lesions,” he explains, “look at it on a vessel level, and then after looking at a vessel level, look on a patient level. And if all of the anatomic lesions are revascularized, we say that there’s complete anatomical revascularization.”

Next, Dr. Ali explains that the terms ‘ischemic,’ ‘functional,’ or ‘physiologic’ revascularization are all essentially the same, but he and his colleagues chose the term ‘ischemic’ because it is ischemia that they are trying to resolve. He walks through Figure 4 from the paper, which describes ischemic revascularization assessment. “One of the things that was very important in the ischemic assessment of complete revascularization,” he states, “is to use a hierarchy of assessment of ischemia.” He explains that invasive physiologic assessment by functional flow reserve (FFR), instantaneous-wave free ratio (iFR), resting full-cycle ratio (RFR), and diastolic pressure ratio (DPR) are considered the gold standard assessment of ischemia. In addition, they consider a stress test with a localizing territory or severe ischemia by exercise treadmill tests as ischemic. If none of these are available, a 70% lesion by QCA or an 80% lesion by visual estimation are also considered to be ischemic. 

Dr. Ali also discusses the timing of complete revascularization which they define not at the index procedure or index hospitalization, but out to 90 days. This, he explains, allows for staged interventions and, for example, failed chronic total occlusion (CTO) requiring healing time before bringing the patient back, or patients on a bypass waiting list. Dr. Ali acknowledges, however, “the earlier you achieve complete revascularization, the longer you have to reap the benefits of it.”

Looking into the future, Dr. Ali hopes that application of these definitions will help clinicians better understand complete anatomic versus complete ischemic revascularization and the goals of each. He also hopes that it will help clinicians identify the “sweet spot” in trials, such as PROTECT IV, where completeness of revascularization will be difficult.