Can CTCA-derived Plaque Characteristics Predict MACE?

A systematic review and meta-analysis recently published in the journal, Circulation, showed a strong association between computed tomographic coronary angiography (CTCA) defined high risk plaque (HRP) features and major adverse cardiovascular events (MACE) in patients with suspected coronary artery disease (CAD).

Dr. Adam Brown, who is the senior author of this study commented, “Our study was the first meta-analysis to investigate the strength of the association between individual CTCA plaque characteristics and future cardiovascular events.” He also added, “By pooling data from thirteen studies, we have shown that the napkin-ring sign appears to confer the highest risk of future events. Importantly, future cardiovascular risk appears to be increased when high-risk plaque features are found in combination.”

This meta-analysis included 13 published studies that enrolled patients with stable cardiovascular disease, had assessment of plaque characteristics including plaque morphology (calcified, noncalcified, and partially calcified) and individual HRP features (low-attenuation plaque, napkin-ring sign, spotty calcification, and positive remodeling), had evaluation of the association between plaque characteristics and future MACE at least 1 year after CTCA.

 

MACE was defined as the composite of cardiac death and nonfatal MI, including unstable angina requiring either hospitalization or revascularization. The primary end point of this study was the association between plaque morphology and subsequent MACE. Secondary end points included the association between specific HRP features on CTCA and MACE.

Overall, MACE occurred in 3.9% of 13977 patients included in this analysis with a mean study follow up ranging from 1.3 to 8.2 years. Among all the CTA assessed plaque characteristics, the strongest association was found between non-calcified plaque and MACE with a 45% increased risk of events; whereas a weaker association was observed between calcified or partly calcified plaque and MACE with a 23% and 37% increased risk of events, respectively.

Of the pre-defined HRP features, the napkin-ring sign was associated with the highest risk of MACE with a 5-fold increased risk. Additionally, low-attenuation plaques and positive remodeling demonstrated an approximately 3 –fold increased risk of MACE. Spotty calcification was associated with the lowest increase in future MACE (2-fold). Patients having 2 or more HRP features were found to be at the highest risk of MACE with a 9-fold increase in cardiovascular events.

When asked about the consensus of the evidence concerning CTA guided plaque characteristics in predicting MACE, Dr. Brown commented, “There is a large and growing body of evidence to suggest a clear link between CTCA plaque characteristics and the risk of future cardiovascular events. However, the strength of this association remains questionable and it is still unclear whether the presence of HRP features adds incremental prognostic information to other CTCA markers of risk, including stenosis severity, total atheroma burden and calcium scoring.”

The study also highlighted the importance of reporting HRP features in a clinical setting for better understanding and risk assessment of MACE. However, further studies need to be done to establish clinical implications of HRP reporting.

When asked about the implications of this study on his clinical practice, Dr. Brown told Cardiology Now, “Our findings support the inclusion of plaque characteristics in the standardized reporting of CTCA datasets and highlight that the presence and extent of high-risk plaque acts as a marker for future cardiovascular risk.” He also added, “Though there remains no consensus on how patients with non-obstructive coronary artery disease on CTCA should be managed, the presence of high-risk plaque may push clinicians to consider the initiation of preventative therapies.”