Combined PCAT Attenuation and High-Risk Plaque Predicts MI

Quick Takes

  • PCAT attenuation measured around the proximal RCA can identify patients who are at an increased risk of MI.
  • This study suggests a complementary predictive value of LAP burden and PCAT attenuation for 5-year risk of fatal or nonfatal MI.
  • Since there were only a modest number of MIs and relatively low event rate in this study, further independent validation of the results is indicated.

Study Questions:

What are the relative and additive values of pericoronary adipose tissue (PCAT) attenuation and low-attenuation noncalcified plaque (LAP) to predict future risk of myocardial infarction (MI)?

Methods:

The investigators conducted a post hoc analysis of the multicenter SCOT-HEART (Scottish Computed Tomography of the Heart) trial. They investigated the relationships between the future risk of fatal or nonfatal MI and PCAT attenuation measured from computed tomography coronary angiography (CTCA) using multivariable Cox regression models including plaque burden, obstructive coronary disease, and cardiac risk score (incorporating age, sex, diabetes, smoking, hypertension, hyperlipidemia, and family history).

Results:

In 1,697 evaluable participants (aged 58 ± 10 years), there were 37 MIs after a median follow-up of 4.7 years. Mean PCAT was -76 ± 8 HU and median LAP burden was 4.20% (interquartile range, 0%-6.86%). PCAT attenuation of the right coronary artery (RCA) was predictive of MI (hazard ratio [HR], 1.55; p = 0.017, per 1 standard deviation increment) with an optimum threshold of -70.5 HU (HR, 2.45; p = 0.01). In multivariable analysis, adding PCAT-RCA of ≥-70.5 HU to an LAP burden of >4% (the optimum threshold for future MI; HR, 4.87; p < 0.0001) led to improved prediction of future MI (HR, 11.7; p < 0.0001). LAP burden showed higher area under the curve (AUC) compared to PCAT attenuation for the prediction of MI (AUC = 0.71 [95% CI, 0.62-0.80] vs. AUC = 0.64 [95% CI, 0.54-0.74]; p < 0.001), with increased AUC when the two metrics are combined (AUC = 0.75 [95% CI, 0.65-0.85]; p = 0.037).

Conclusions:

The authors concluded that CTCA–defined LAP burden and PCAT attenuation have marked and complementary predictive value for the risk of fatal or nonfatal MI.

Perspective:

This post hoc analysis of a prospective multicenter study reports that PCAT attenuation measured around the proximal RCA can identify patients who are at an increased risk of MI. Furthermore, this association persisted following adjustment for clinical cardiovascular risk score, coronary artery calcium score, and the presence of obstructive coronary artery disease. This study also suggests a complementary predictive value of LAP burden and PCAT attenuation for 5-year risk of fatal or nonfatal MI. There were only a modest number of MIs, and given the relatively low event rate in this study, further independent validation of the results is indicated.

Clinical Topics: Acute Coronary Syndromes, Cardiovascular Care Team, Dyslipidemia, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Prevention, Atherosclerotic Disease (CAD/PAD), Interventions and ACS, Interventions and Coronary Artery Disease, Interventions and Imaging, Angiography, Computed Tomography, Nuclear Imaging, Hypertension, Smoking

Keywords: Acute Coronary Syndrome, Adipose Tissue, Computed Tomography Angiography, Coronary Angiography, Coronary Artery Disease, Diabetes Mellitus, Diagnostic Imaging, Heart Disease Risk Factors, Hyperlipidemias, Hypertension, Myocardial Infarction, Plaque, Atherosclerotic, Risk Factors, Secondary Prevention, Smoking


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