Author + information
- James K. Min, MD∗ ()
- ↵∗Weill Cornell Medical College, New York-Presbyterian Hospital, Dalio Institute of Cardiovascular Imaging, 413 East 69th Street, Suite 108, New York, New York 10021
We thank Dr. Ramanna for his interest in our paper (1) that details the relationship of atherosclerotic plaque characteristics (APCs) and coronary ischemia by fractional flow reserve (FFR). We identified a strong and positive relationship with % aggregate plaque volume, positive arterial remodeling and low attenuation plaque (a surrogate marker for lipid-laden plaque) with coronary ischemia by FFR. Dr. Ramanna commented on the potential mechanisms associated with these findings—impaired vasodilation, diffuse atherosclerosis, and microcirculatory dysfunction—as we discussed in detail in our paper. His hypothesis is that the increased ischemia associated with APCs is due to coexistent diffuse atherosclerosis, which is certainly a potential explanation. Dr. Ramanna also believes that it is unlikely that impaired vasodilation in diseased vessels is the cause of the observed coronary ischemia, as he suggests that impaired vasodilation will reduce overall hyperemic flow and thus increase FFR values. However, any particular coronary lesion with APCs may cause local rather than global impairment in adenosine-mediated vasodilation, which will serve to increase flow proximal to the stenosis and relatively decrease flow distal to the stenosis, thus reducing the FFR. In this regard, APCs by computed tomography may be anatomic surrogates of local physiological effects of plaque that impair vasodilation or cause vasoconstriction.
Dr. Ramanna raises very important points regarding the intrinsic relationship of FFR to vasodilation, flow, diffuse disease, and microvascular disease; and emphasizes the complexity of these relationships to identify coronary ischemia. Future metrics that can account for luminal narrowing and its effect on physiologically realistic ranges of coronary flow, while accounting for the totality of atherosclerosis burden and patient-specific microcirculatory function, will help elucidate the relative contributions of each of these variables.
Please note: Dr. Min is a consultant to HeartFlow and GE Healthcare.
- American College of Cardiology Foundation