Low-attenuated plaques and positive vessel remodeling associated with ACS

Patients with plaques that have low attenuation and also have positive coronary segment remodeling as assessed by computed tomography angiography are more likely to develop an acute coronary syndrome.

Researchers examined 1,059 patients who underwent CTA. Atherosclerotic lesions were analyzed for the presence of positive vessel remodeling and low-attenuation plaques. Plaque characteristics of lesions resulting in ACS during the 27 ± 10 month follow-up period were evaluated.

The researchers reported that 15 of the 1,059 patients who underwent CTA developed an ACS during the follow-up period. Forty-five patients had plaques with both positive vessel remodeling and low attenuation, and 10 of those patients developed an ACS (22.2%). Of the 27 patients who displayed plaques with at least one feature, only one developed ACS (3.7%). The researchers also reported an increased likelihood of developing an ACS in patients with either one-feature or two-feature positive plaques compared with patients with two-feature negative plaques or no plaques (22.2% vs. 3.7% vs. 0.49%, P<.001). A multivariable Cox regression analysis revealed that the presence of one-feature or two-feature positive plaques was the only independent predictor of ACS (HR=22.8; 95% CI, 6.9-75.2).

“The present CTA study demonstrates that coronary plaques that are likely to result in subsequent ACS during follow-up are often voluminous and contain large areas of low attenuation; these coronary plaques are associated with positive vascular remodeling,” concluded the researchers. “Although larger and longer follow-up studies will be necessary for establishing the role of CTA in high-risk asymptomatic subjects, these CT characteristics confirm previously reported pathologic features of unstable plaques.”

In an accompanying editorial, Eugene Braunwald, MD,chairman of the TIMI Study Group at Brigham and Women’s Hospital in Boston, noted that CTA has recently emerged an important approach for the noninvasive evaluation of the coronary anatomy and the characterization of plaques.

“The widespread clinical application of the approach of Motoyama et al for the detection of vulnerable plaques at risk of future rupture (namely, locking the barn door before the horse is stolen) would require the development of measures for the prevention of plaque rupture that are more potent than those currently employed, in what we currently refer to as intensive prevention,” Braunwald, also a member of the Cardiology Today editorial board, wrote in the editorial. “When more effective therapies for these plaques do become available, the paper by Motoyama et al will surely become a landmark in the effort to prevent ACS.”

For more information:

Motoyama S. J Am Coll Cardiol. 2009;54:49-57.