Abstract 2545: Revisiting the Coronary Arterial ‘Hot-Spot’ Hypothesis with Angiography-IVUS Fusion Methodology: Is Proximal Vessel Plaque Accumulation More Closely Related to Vessel Location or Vessel Size?
Background: Previous work suggests that acute clinical events tend to cluster in the proximal third of the coronary vasculature. While myocardial-infarction causing events may occur at sites which have greater plaque burden, it may also be possible that the proximal location may be more important than the degree of atherosclerosis or plaque accumulation. Understanding whether absolute vessel location (as previously hypothesized) or vessel size is more relevant for the development of plaque accumulation would aid in our understanding of where clinical ischemic events are likely to occur.
Methods: Data from geometric 3-D fusion of angiography and IVUS in 60 patients (mean age 61, LAD 35%, LCX 27%, RCA 37%) undergoing PCI were analyzed, with frames in bifurcations excluded. Starting from the vessel ostium, luminal and vessel cross-sectional areas (CSA) were determined and plaque CSA calculated in 8237 frames. The measurements were clustered and averaged in 5mm distance intervals from the ostium. Linear regression was used to pair-wise correlate plaque CSA, vessel CSA, and distance from the ostium.
Results: For all vessels (LAD, LCX, RCA), correlation of the clustered measurements showed a tight relationship of both plaque CSA vs. absolute vessel location (R2=0.958) and plaque CSA vs. vessel CSA (R2=0.958). The regression analysis for plaque vs. vessel CSA indicated that plaque burden is proportionally higher in locations with large vessel CSA compared with those of small vessel CSA. The highest correlation was found between vessel CSA and location (R2=0.973), thus vessel CSA implicitly reflects distance from the ostium. All correlations were significant (p<0.001).
Conclusions: Plaque volume in atherosclerotic coronary vessels tends to accumulate in the proximal vasculature, similar to the known distribution of clinical events. However, the relationship between plaque area and vessel size is equally correlated, where plaque burden is generally higher in large vessel segments. Further studies are needed to confirm whether clinical events in individual patients occur preferentially in proximal vessels because of the local milieu including hemodynamic stresses, or whether clinical events follow plaque burden, which is tightly related to vessel size.