Clinical study
Mechanical and structural characteristics of vulnerable plaques: analysis by coronary angioscopy and intravascular ultrasound

https://doi.org/10.1016/S0735-1097(01)01315-8Get rights and content
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Abstract

OBJECTIVES

Mechanical and structural characteristics of vulnerable plaques were evaluated using coronary angioscopy and intravascular ultrasound.

BACKGROUND

Mechanical stress and composition of plaques play an important role in plaque disruption.

METHODS

Thirty-eight lesions in 38 patients were examined pre-interventionally. The plaques were classified as either yellow or white using coronary angioscopy. Intravascular ultrasound imaging was performed simultaneously with electrocardiographic and intracoronary pressure recordings to calculate distensibility index and stiffness β. Moreover, the type of remodeling was classified.

RESULTS

We identified 27 patients with yellow plaques and 11 patients with white plaques. Patients with yellow plaques presented acute coronary syndromes more frequently than stable angina (85% vs. 36%, p < 0.01). The distensibility index in yellow plaques was significantly greater than it was in white plaques (2.7 ± 0.8 mm Hg−1vs. 0.7 ± 0.8 mm Hg−1, p < 0.0001), while stiffness β for white plaques was significantly greater than it was for yellow plaques (34.9 ± 16.3 vs. 8.7 ± 2.7, p < 0.0001). Compensatory enlargement occurred more frequently with yellow plaques than with white plaques (56% vs. 9%, p < 0.01), while paradoxical shrinkage occurred more frequently with white plaques than it did with yellow plaques (64% vs. 4%, p < 0.001).

CONCLUSIONS

Yellow plaques with an increased distensibility and a compensatory enlargement may be mechanically and structurally weak. As a result, mechanical “fatigue,” caused by repetitive stretching, may lead to plaque disruption. Plaques with a high distensibility and a compensatory enlargement may be vulnerable.

Abbreviations

CSA
cross-sectional area
DBP
diastolic intracoronary pressure
EEM
external elastic membrane
IVUS
intravascular ultrasound
RR
remodeling ratio
SBP
systolic intracoronary pressure

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