The Use of Pressure Gradient in the Diagnosis of Restenosis

The limitation of coronary angiography to assess the functional significance of coronary stenosis as well as coronary restenosis has been recognized for years (1,2). It is well known that the angiographic assessment of an epicardial lesion correlates poorly with its physiological relevance (3,4). Coronary angiography with its inherent limitations may not reliably predict whether a stenosis produces ischemia (5). In addition, the determination of the severity of stenoses varies significantly among observers. In one study, experienced operators disagreed 30% of the time when deciding on the number of coronary arteries with a 70% stenosis (6). Despite these limitations the decision for performing an intervention is often based on the angiographic appearance of a coronary lesion. It is known from many angiographic studies that revascularization rate increases after scheduled control angiography meaning that repeat intervention is more often based on morphological criteria, i. e., quantitative coronary angiography or solely “eye balling” than on physiological considerations (7). Furthermore, as restenosis, which means in most of the cases in-stent restenosis may occur as a diffuse, proliferative process, the assessment of the hemodynamic significance is even more complex by angiography alone.