Abstract 14049: Low Coronary Wall Shear Stress Occurs Most Frequently in Segments Immediately Distal to Lesions while High WSS occurs Most Frequently Within the Lesions: An Evaluation in Patients With Coronary Artery Disease
Introduction: Coronary atherosclerotic plaques result in alterations of focal wall shear stress (WSS). While computational and experimental studies have shown lower WSS values in segments immediately distal to lesions compared to segments proximal to and within the lesions, this phenomenon has not been demonstrated in patients with CAD.
Methods: Accordingly, 27 patients with non-obstructive CAD underwent intravascular ultrasound (IVUS) and Doppler velocity measurement for computation fluid dynamics modeling to calculate coronary WSS in each IVUS segment (n=3,581, each 0.5mm thickness). Atherosclerotic lesion segments were defined by segments with IVUS-derived plaque burden exceeding 40% over three consecutive IVUS segments. Low WSS was defined as <10 dynes/cm2 and high WSS as ≥25 dynes/cm2. We compared WSS in segments within the lesions, 5mm proximal and 5mm distal to lesions.
Results: Of total 3,581 IVUS segments, 1,390 resided within a lesion, 226 proximal to a lesion, and 252 segments distal to a lesion. Distal segments demonstrated the lowest mean WSS (p<0.001) and the highest percentage of segments with low WSS (p<0.001), while lesion segments demonstrated the highest mean WSS (p<0.001) and the highest percentage of segments with high WSS (p<0.001), Figure. Interestingly, the lower WSS in distal segments occurred despite similar amount of plaque burden (p=0.79) and smaller lumen (p<0.0001) compared to the proximal segments.
Conclusions: In patients with CAD, low WSS occurs most frequently in segments immediately distal to lesions, likely due to a localized effect of reduced WSS distal to a lesion, while high WSS occurs most frequently within the lesions. Our in vivo findings confirm the theoretical concepts of fluid dynamics and may provide an insight to the role of low WSS in distal progression of plaques in human coronary arteries.
- © 2011 by American Heart Association, Inc.