Elsevier

Atherosclerosis

Volume 219, Issue 2, December 2011, Pages 573-578
Atherosclerosis

Relationship of coronary artery plaque composition to coronary artery stenosis severity: Results from the prospective multicenter ACCURACY trial

https://doi.org/10.1016/j.atherosclerosis.2011.05.032Get rights and content

Abstract

Objectives

The purpose of this study was to determine the relationship of coronary artery plaque composition as detected by coronary computed tomographic angiography (CCTA) to luminal diameter stenosis severity quantified by quantitative coronary angiography (QCA) in individuals without known coronary artery disease (CAD) presenting with stable chest pain syndrome.

Background

While CCTA has been previously evaluated for its ability to detect and exclude coronary artery stenosis, CCTA also permits assessment of other important plaque characteristics, including plaque composition. Identification of the relationship between plaque composition by CCTA and plaque severity by invasive angiography may provide valuable insight into the pathophysiology of coronary artery plaque.

Methods

Patients enrolled in the ACCURACY trial, a 16-site multicenter study of patients with stable chest pain syndrome but without known CAD undergoing both CCTA and invasive coronary angiography (ICA), comprised the study population. CCTAs were scored on a per-segment basis for plaque composition and graded as non-calcified (>70% non-calcified), calcified (>70% calcified) or “mixed” (30–70% non-calcified or calcified) by concordance of ≥2 of 3 readers. CCTAs were also scored on a per-patient basis, and individuals were categorized as possessing primarily non-calcified plaques, primarily calcified plaques or primarily mixed plaques. Quantitative coronary angiography (QCA) was performed in all patients, used as the reference standard for stenosis severity, and interpreted blinded to patient characteristics and CCTA results.

Results

230 subjects comprised the study population (59.1% male, 57 ± 10 years). QCA was performed in all subjects following CCTA (mean inter-test interval 5.9 ± 4.3 days), and demonstrated obstructive CAD in 24.8% and 13.9% at the 50% and 70% stenosis severity threshold, respectively. On a per-segment based analysis, obstruction by QCA at both the 50% and 70% stenoses thresholds was more often for mixed composition plaques by CCTA (69.1% and 67.9%, respectively), as compared to non-calcified plaques (24.7% and 28.6%, respectively) and calcified plaques (6.1% and 3.6%, respectively) [p < 0.01 for comparisons]. On a per-patient basis, patients with mixed plaque or mixtures of plaque types more often exhibited obstructive coronary stenosis by QCA at the 50% level (39/96; 40.6%) compared to those with primarily non-calcified (12/43; 27.9%) or primarily calcified (4/29; 13.8%) plaques [p = 0.02].

Conclusions

In this multicenter trial of chest pain patients without known CAD, QCA-confirmed obstructive coronary stenosis was associated with mixed plaque composition by CCTA at both the per-segment and the per-patient levels. Coronary artery segments exhibiting calcified plaque were rarely associated with obstructive coronary stenosis.

Introduction

Coronary computed tomographic angiography (CCTA) has emerged as accurate non-invasive method for the detection and exclusion of obstructive coronary artery disease (CAD) [1], [2], [3]. Further, CCTA permits evaluation of numerous other coronary artery plaque characteristics, including plaque compositions, which are generally graded as non-calcified, calcified and mixed [4]. Classification of plaques by CCTA based upon composition has important clinical implications, with increasing numbers of mixed plaques possessing thin cap fibroatheroma, associated with myocardial ischemia and predictive of adverse CAD prognosis [5], [6], [7], [8]. To date, however, the relationship of plaque composition by CCTA to luminal diameter stenosis severity remains unknown.

The aim of this prospective multi-center study was to determine the relationship of coronary artery plaque composition by CCTA to QCA-confirmed luminal diameter stenosis severity in chest pain subjects without known CAD. We evaluated these relationships on a per-segment and per-patient basis.

Section snippets

Patients

The Assessment by coronary computed tomographic angiography of individuals undergoing invasive coronary angiography (ACCURACY) study was designed to prospectively evaluate adult subjects with chest pain who were being clinically referred for non-emergent invasive coronary angiography (ICA) [1]. Potential study subjects were screened and enrolled by a site research coordinator if they met all of the inclusion and none of the exclusion criteria. Study subjects were asked to undergo a research

Patient characteristics

230 subjects met study eligibility criteria, including completion of both CCTA and ICA (mean interval 5.9 ± 4.3 days). The mean Agatston score was 284 ± 538 (Table 1).

Segment-based evaluation

Amongst 2954 coronary segments identified, consensus was achieved for at least 2 of 3 readers in 98.8% (2918/2954). Amongst CCTA-identified plaques, mixed plaques were the most common (43.9%; 319/727), followed by calcified (28.3%; 206/727) and non-calcified (27.8%; 202/727) plaques. There was a significant relationship between plaque

Discussion

These results of the ACCURACY trial represent the first prospective multicenter data relating plaque composition by CCTA to QCA-confirmed measures of luminal diameter stenosis severity. The current data demonstrate a strong association between the presence of mixed plaque composition to obstructive coronary artery stenosis at a per-segment and per-patient level. In addition, these data establish a negative association between calcified plaque composition and stenosis severity, particularly on a

Conclusion

In this multicenter trial of chest pain patients without known CAD, QCA-confirmed obstructive coronary stenosis was associated with presence of mixed plaque composition by CCTA at both the per-segment and the per-patient levels. Coronary artery segments exhibiting calcified plaque were rarely associated with obstructive coronary stenosis.

Acknowledgements

GE Healthcare sponsored and coordinated the study to ensure that good clinical practices and data integrity were achieved (ClinicalTrials.gov Identifier: NCT00348569). In addition, GE Healthcare provided recommendations for computed tomography X-ray dosing and injection protocols, site training, and logistical support for data transfer from individual sites to the core laboratories. GE Healthcare allowed the Principal Investigators to direct the data analysis, manuscript preparation, and review

References (15)

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