Inter- and Intra-Observer Variability for the Assessment of Coronary Artery Tree Description and Lesion Evaluation (CatLet©) Angiographic Scoring System in Patients with Acute Myocardial Infarction
The Coronary Artery Tree description and Lesion EvaluaTion (CatLet©) angiographic scoring system represents a novel approach to assessing coronary anatomy and stratifying risk in patients with acute myocardial infarction (AMI). This system was developed to address the limitations of existing scoring tools, such as the SYNTAX score, by incorporating variability in coronary anatomy and providing a more comprehensive evaluation of lesions. The CatLet score has shown promise in predicting clinical outcomes for AMI patients, but its reproducibility among different observers and over time remained to be validated. This study aimed to evaluate the inter- and intra-observer variability of the CatLet scoring system, ensuring its reliability for clinical application.
The CatLet scoring system is based on a 17-myocardial segment model, the law of flow conservation, and the law of competitive blood supply. It classifies the right coronary artery (RCA) into six types, the left anterior descending artery (LAD) into three types, and the diagonal arteries (Dx) into three types, resulting in 54 possible coronary circulation patterns. This classification accounts for the variability in coronary anatomy, which is a significant improvement over the SYNTAX score. The CatLet score assigns weights based on the number of myocardial segments supplied by each coronary artery, and only lesions with a diameter stenosis of 50% or more in vessels larger than 1.5 mm are scored. Adverse characteristics of lesions, such as bifurcation or calcification, are qualitatively recorded but not scored, simplifying the process and potentially improving reproducibility.
To assess the reproducibility of the CatLet score, the study included two separate cohorts of AMI patients. The first cohort consisted of 30 patients admitted in September 2015, who were independently evaluated by two experienced interventional cardiologists to determine inter-observer variability. The second cohort included 49 patients admitted between September and October 2014, who were evaluated by one cardiologist on two occasions, three months apart, to assess intra-observer variability. The weighted kappa statistic was used to measure the degree of agreement between observers and over time.
The results demonstrated excellent reproducibility for the CatLet score. The weighted kappa values for intra-observer and inter-observer agreement were 0.82 and 0.86, respectively, indicating almost perfect agreement. These values were higher than those reported for the SYNTAX score, which typically range from 0.45 to 0.78. The high reproducibility of the CatLet score can be attributed to its systematic approach to classifying coronary anatomy and its simplified scoring criteria, which minimize subjectivity.
In addition to the overall CatLet score, the study evaluated the reproducibility of specific adverse lesion characteristics and dominance parameters. For inter-observer variability, the kappa values were 0.80 for the total number of lesions, 0.57 for bifurcation lesions, 0.69 for heavy calcification, 1.00 for tortuosity, 0.54 for thrombus, 0.69 for RCA dominance, 0.69 for LAD length, and 0.22 for Dx size. Intra-observer variability showed similar results, with kappa values ranging from 0.54 to 1.00. These findings indicate that the CatLet scoring system performs well in assessing both lesion characteristics and coronary dominance, with the exception of Dx size, which showed only fair agreement between observers.
The study also highlighted the challenges in evaluating certain lesion characteristics, such as bifurcation and Dx size. The lower reproducibility for these parameters may be due to differences in interpretation or the lack of standardized views in coronary angiography. However, the overall reproducibility of the CatLet score for adverse lesion characteristics was still better than that of the SYNTAX score, which struggles with similar issues.
The CatLet scoring system’s ability to account for variability in coronary anatomy is a significant advantage over the SYNTAX score. By classifying coronary circulation patterns and assigning weights based on myocardial segment supply, the CatLet score provides a more accurate and consistent assessment of coronary disease severity. This is particularly important in AMI patients, where rapid and reliable risk stratification is critical for guiding treatment decisions.
The study’s findings have important implications for clinical practice. The high reproducibility of the CatLet scoring system supports its use as a reliable tool for evaluating coronary anatomy and stratifying risk in AMI patients. Its simplified scoring criteria and systematic approach make it easier to use than the SYNTAX score, potentially reducing the learning curve for interventional cardiologists. Furthermore, the CatLet score’s ability to predict clinical outcomes more accurately than the SYNTAX score underscores its potential to improve patient care.
Despite its strengths, the study has some limitations. The evaluation of borderline lesions (around 50% diameter stenosis) remains challenging and could affect scoring results. Incorporating fractional flow reserve (FFR) measurements may improve reproducibility in these cases. Additionally, the study focused exclusively on AMI patients, and further research is needed to validate the CatLet score in other populations with coronary artery disease. Finally, the exclusion of small vessels (1.5–2.0 mm in diameter) from scoring may limit the system’s applicability in certain cases, although this approach is consistent with the SYNTAX score.
In conclusion, the CatLet angiographic scoring system demonstrates excellent reproducibility for both inter- and intra-observer assessments, making it a reliable tool for evaluating coronary anatomy and stratifying risk in AMI patients. Its ability to account for variability in coronary anatomy and predict clinical outcomes more accurately than the SYNTAX score highlights its potential to improve patient care. Future studies should explore the integration of FFR measurements and validate the CatLet score in broader populations to further enhance its clinical utility.
doi.org/10.1097/CM9.0000000000001208
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