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Clinical and Angiographic Characteristics of Patients Likely to Have Vulnerable Plaques: Analysis From the PROSPECT Study
Study Questions:
Can clinical and angiographic findings identify patients who are more likely to have vulnerable coronary plaque?
Methods:
This study examined 609 patients admitted with acute coronary syndrome undergoing successful revascularization and three-vessel intravascular ultrasound (IVUS) imaging as part of the PROSPECT (Providing Regional Observations to Study Predictors of Events in the Coronary Tree) trial; the present analysis examined patient and angiographic characteristics to determine whether these could predict patients more likely to have at least one vulnerable plaque (defined as ≥2 high-risk features, including a thin-cap fibroatheroma, a plaque burden of ≥70%, and/or a minimal luminal area of ≤4 mm2).
Results:
Between patients with versus without at least one vulnerable plaque by IVUS, the only significant differences in age, gender, medical history, or presentation were Framingham risk score (7.5 ± 3.4 vs. 6.9 ± 3.3, p = 0.04) and serum triglycerides (138.0 vs. 121.5 mg/dl, p = 0.04). By quantitative coronary angiography, patients with versus without ≥1 vulnerable plaque had a larger number of vessels with culprit (1.4 ± 0.5 vs. 1.3 ± 0.4, p = 0.04) and nonculprit lesions (1.6 ± 1.0 vs. 1.3 ± 1, p = 0.01), as well as increased total length and number of nonculprit lesions, and lesions in side branches (p < 0.001 for each). Patients with vulnerable plaques had increased risk of future cardiovascular events associated with nonculprit lesions (hazard ratio, 2.6; 95% confidence interval, 1.6-3.7; p < 0.001). The ability of patient characteristics to identify patients with vulnerable plaque was limited (area under the curve [AUC], 0.55), and did not substantially improve with the addition of angiographic findings (AUC, 0.64).
Conclusions:
The authors concluded that patient and angiographic characteristics have limited ability to identify patients with vulnerable plaque.
Perspective:
The PROSPECT study has previously demonstrated that plaque burden, minimal luminal area, and the presence of thin-cap fibroatheroma by IVUS are associated with future cardiovascular events. Nevertheless, it may not be practical to routinely perform three-vessel IVUS in patients presenting with acute coronary syndrome, and there is a need for other methods to identify patients more likely to have high-risk plaque. This manuscript finds that clinical variables have poor accuracy to identify patients with vulnerable plaque characteristics observed by IVUS, and that addition of angiographic findings does not substantially improve discrimination of these individuals. It appears that additional testing may be needed to identify patients with vulnerable plaque, whether by IVUS or other potential alternatives such as coronary computed tomography angiography or nuclear imaging.
Keywords: Coronary Artery Disease, Acute Coronary Syndrome, Plaque, Atherosclerotic, Coronary Angiography, Tomography, Triglycerides, Cost of Illness
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