What is the clinical evidence from this study?

Study design: Case-Control. Population: Acute Coronary Syndrome (n=231). Intervention: CT radiomics of coronary artery calcification (kurtosis and median attenuation) vs. Standard Agatston score and traditional risk factors. Primary outcome: Association of higher kurtosis of CAC attenuation with acute coronary syndrome (OR 18.7, 95% CI 5.86-60.0, p=<0.001).

What does this research mean for the field?

Higher kurtosis and lower median attenuation of coronary artery calcification are independently associated with acute coronary syndrome and vulnerable plaques, providing better risk assessment than the standard Agatston score. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

March 27, 2023Open Access

Lower attenuation and higher kurtosis of coronary artery calcification associated with vulnerable plaque – an agatston score propensity-matched CT radiomics study

Q: What are the key findings of this study?

Higher kurtosis (OR 18.7) and lower median attenuation (OR 0.969) of coronary artery calcification were independently associated with acute coronary syndrome compared to asymptomatic controls.

Q: What does this research mean for the field?

Higher kurtosis and lower median attenuation of coronary artery calcification are independently associated with acute coronary syndrome and vulnerable plaques, providing better risk assessment than the standard Agatston score. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

EHEric HuangNational Yang Ming Chiao Tung University HLHuey‐Shyan LinFooyin University YCYi‐Chun ChenTaipei Medical University Hospital

Key Result

Higher kurtosis (OR 18.7) and lower median attenuation (OR 0.969) of coronary artery calcification were independently associated with acute coronary syndrome compared to asymptomatic controls.

Study Design

Type

Case-Control (n=231)

Multicenter

Structured PICO

Do CT radiomics features of coronary artery calcification differentiate vulnerable plaques in ACS patients from stable plaques in asymptomatic subjects?

Population

261 subjects (77 ACS patients matched 1:2 with 154 asymptomatic subjects, plus a validation cohort of 10 ACS and 20 asymptomatic subjects), mean age 61.5 years, predominantly male, in Taiwan. Key inclusion: ACS patients with a CAC scan before percutaneous coronary intervention, matched for traditional risk factors and Agatston score ranks.

Intervention

CT radiomics analysis of coronary artery calcification (CAC) plaques on non-contrast ECG-gated CT

Comparator

Asymptomatic subjects matched for traditional risk factors and Agatston score ranks

Outcome

Association of CAC radiomics features (median attenuation and kurtosis) with acute coronary syndrome statussurrogate

CT radiomics of coronary artery calcification reveals that lower median attenuation and higher kurtosis are independent characteristics of vulnerable plaques in patients with acute coronary syndrome.

Main Result

Effect estimate: OR 18.7 (95% CI 5.86-60.0)

p-value: p=<0.001

Limitations

Biases outside the propensity scoring, such as precise medication and laboratory data, could not be eliminated.
Manual analysis of CAC radiomics using LIFEx software.
Some plaques were insufficient in size and shape for 2nd-order texture analysis, limiting analysis to 1st-order parameters.
Medication information (e.g., statins) was not included or matched between cohorts.
The interval time between the CAC scan and the diagnosis of acute coronary syndrome was not evaluated.
All participants were enrolled in a single medical center, limiting generalizability.

Abstract

BACKGROUND: Coronary artery calcification (CAC) burden assessed by Agatston score (AS) is currently recommended to stratify patients at risk for future acute coronary syndrome (ACS). Besides the CAC burden, the biostructure of CAC may also play a vital role in the vulnerability of CAC, which CT radiomics could reveal. Propensity-score matching of the traditional risk factors and CAC burden between the ACS and asymptomatic groups could radically remove biases and allow the exploration of characteristic features of CAC in ACS. METHODS: We retrospectively identified 77 patients with ACS who had a CAC scan before percutaneous coronary intervention between 2016 and 2019. These 77 patients were one-to-two propensity-score matched for traditional risk factors of ACS and AS ranks to select 154 subjects from 2890 asymptomatic subjects. A validation cohort of 30 subjects was also enrolled. Radiomics features of each plaque were extracted and averaged in each person. Conditional logistic regression and area-under-curve analysis were used for statistical analysis. RESULTS: A higher number of coronary segments involved, lower mean, median, first quartile, and standard deviation of attenuation, and increased kurtosis of attenuation of CAC were associated with the ACS group compared to the control group (p < 0.05 for all). Multivariable analysis showed that the lower median attenuation (OR = 0.969, p < 0.001) and higher Kurtosis (OR = 18.7, p < 0.001) were associated with the ACS group. The median attenuation and kurtosis significantly increase across AS ranks 1 to 4 (p = 0.001). The AUC of kurtosis (0.727) and median attenuation (0.66) were both significantly higher than that of the standard AS (AUC = 0.502) and the number of TRF (AUC = 0.537). The best cut-off of kurtosis at 2.74 yielded an accuracy of 74%, and the cut-off of median attenuation at 196 yielded an accuracy of 68%. The accuracy of kurtosis was 64%, and the accuracy of median attenuation was 55% in the validation cohort. CONCLUSION: After propensity-matching traditional risk factors and CAC burden, CT radiomics highlighted that lower median attenuation and higher kurtosis were the CAC characteristics of vulnerable plaques. These features improve the understanding of the biomechanics of CAC evolution and enhance the value of CAC scan in ACS risk assessment.

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