Abstract 2556: Understanding Spatial Location of ‘Glagov-Significant’ Coronary Plaque Accumulation as Measured with Angiography-IVUS Fusion: Is Significant Cross-Sectional Area Narrowing More Likely to Occur at Proximal Vessel Clinical ‘Hot Spots’?
Background: Angiographic and IVUS studies demonstrated that acute clinical events (Myocardial Infarction) tend to cluster in the proximal third of the coronary vasculature. Mechanisms for arterial remodeling are compromised once the vessel reaches the ‘Glagov-significant’ threshold (GST) of 40% cross sectional narrowing (CSN). Resolving if atherosclerotic CSN beyond the GST also cluster proximally would aid in our understanding of whether acute clinical events occur at sites with significant atherosclerosis or rather in specific vessel locations irrespective of CSN.
Methods: Geometric 3-D fusion of angiography and IVUS data from 60 patients (mean age 61, LAD 35%, LCX 27%, RCA 37%) undergoing PCI for stable or unstable CAD was performed. Bifurcations were excluded. Starting from the vessel ostium, %-area stenosis was computed and averaged over 5mm wide sets of IVUS frames, resulting in 871 measurements. The proportion of measurements significantly exceeding the GST (40% CSN), defined by CSN of >60%, was plotted in individual vessel types as a function of distance from ostium and clustered into 5 segments.
Results: The LAD showed the highest frequency of 53.2% highly stenotic (CSN >60%) locations in the 0 –25mm segment, with a mid-vessel decrease, and a slight distal increase. RCA follows an identical trend with overall higher incidence of plaque. LCX shows the least frequency of highly stenotic locations, dominant in the 0 –50mm ranges and below 60% CSN in the most distal segment. Locations with CSN >60%
Conclusions: There is a clear relationship between plaque severity and events attributed to proximal vessel segments. Significant coronary plaque accumulation, measured by CSN, occurs more commonly at proximal locations in a pattern similar to the previously established distribution of clinical events related to plaque rupture. In the RCA, the distribution of segments with significant CSN extends more distally, corresponding to previously established more diffuse occurrence of events.