Compliance mismatch between stenotic and distal reference segment is associated with coronary artery disease instability.
OBJECTIVE
Inflammation and structural factors such as a thin fibrous cap, positive remodeling and large lipid pool have been established as factors associated with coronary plaque instability. This study aimed to investigate the hypothesis that the differential in coronary artery compliance between stenotic and adjacent arterial segments is another factor associated with unstable coronary disease.


METHODS
Forty-one patients undergoing a percutaneous coronary intervention were classified as unstable coronary syndrome (n=19) or stable angina (n=22). Intravascular ultrasound was used to assess external elastic lamina (EEL) cross-sectional area at diastole and systole. Aortic pressure was determined from the coronary guiding catheter. Coronary cross-sectional compliance (C) was calculated as the quotient of systolic-to-diastolic area differential and pulse pressure. C was measured within the stenosis and the adjacent reference segments.


RESULTS
EEL cross-sectional area was greater in systole than in diastole in the reference segments, but did not differ within the lesion site. C was greater in the distal reference than the stenotic segments (7.7+/-13.1 vs. 0.0+/-12.3mm(2)mmHg(-1)x10(3), p=0.003). When dichotomized by clinical presentation, the distal-to-stenosis compliance difference was only significant in the unstable coronary syndrome group (stable: distal 4.1+/-13.3 vs. stenosis -0.3+/-13.2mm(2)mmHg(-1)x10(3), ANOVA p=0.48; unstable: distal 11.9+/-11.9 vs. stenosis 0.1+/-11.6mm(2)mmHg(-1)x10(3), ANOVA p=0.006, distal-to-stenosis difference p=0.001).


CONCLUSIONS
A difference between stenotic and distal reference segment coronary compliance was evident in unstable, but not stable coronary artery disease patients. Coronary compliance differential would increase cyclical forces in the plaque shoulder region, which may contribute to plaque disruption.
Alfred Hospital and Baker IDI Heart and Diabetes Institute, St. Kilda Road Central, VIC 8008, Melbourne, Australia.
Anthony J
AJ
White
Stephen J
SJ
Duffy
Antony S
AS
Walton
Swati
S
Mukherjee
James A
JA
Shaw
Garry L R
GL
Jennings
Anthony M
AM
Dart
Bronwyn A
BA
Kingwell
D000368:Aged; D000787:Angina Pectoris / Q000000981:diagnostic imaging / Q000473:pathology; D000789:Angina, Unstable / Q000000981:diagnostic imaging / Q000473:pathology; D003187:Compliance; D017023:Coronary Angiography; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging / Q000473:pathology*; D023921:Coronary Stenosis / Q000000981:diagnostic imaging / Q000473:pathology; D003331:Coronary Vessels / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology; D003971:Diastole; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D013599:Systole; D018084:Ultrasonography, Interventional