Welcome to accessing the CatLet score calculator ©



Software-based CatLet score algorithm

The CatLet score calculation is feasible by use of a computer program consisting of sequential and interactive self-guided questions (available at http://www.catletscore.com).

The algorithm includes 15 main questions. The first question includes 3 sub questions: RCA dominance, Dx size and LAD length. Answering these 3 sub-questions will define one of 54 types of coronary artery circulations proposed in this angiographic scoring system (different from the SYNTAX score) (13). The second question includes two options: option 1 is for recording normal coronary artery anatomy; and option 2 (most important) is for evaluating the lesions. Question 3 addresses lesion-based unlimited segment selection. Question 4 addresses 2 native or in-stent lesion types, including non-occlusions and acute total occlusion (ATO).

For non-occlusion or ATO lesions, questions 5-12 address the lesion-based evaluation, including involved segments, calcifications, angulations, and thrombus, which are most similar to those adopted in the SYNTAX score (13), but differ in only qualitatively recording these adverse characteristics as “Yes” or “No” in our scoring system (table 7). Question 12 addresses scoring modification if necessary. Upon completion of question 12, the algorithm proceeds to the last question or to another cycle of “add another lesion”. The last question of the CatLet score algorithm, diffuse disease/small vessels, similar to those in the SYNTAX score, is also only qualitatively recorded (table 7). For a patient with coronary artery disease, it takes around 5-10 minutes to process a patients depending on the complexity and severity of coronary artery disease.

Table 7. Scoring and describing of lesion’s adverse characteristics.

In the CatLet score, only the lesion's stenosis was scored, and the lesion's remaining adverse characteristics were instead qualitatively recorded. CTO is defined an occluded coronary segment with TIMI flow 0 for ≥3 months duration. Definitions for lesions' adverse characteristics are the same as listed in the Syntax score (13). In-stent lesions are defined as angiographic diameter stenosis >50% at the stent segment or its adjacent edges within 5 mm (15).

Scoring of a sample patient according to the CatLet angiographic scoring system

As shown in Figure 16, coronary circulation pattern was first evaluated overall according to LAD length, Dx size and RCA size (Figure 16A-C) before the non-occlusive lesion on proximal LAD (segment 6) was scored. Average RCA was judged according to the presence of a significant branch arising from LCX. The lesion was amplified right upper in the Figure 16C. Adverse non-stenotic characteristics pertinent to the lesion were no longer scored and qualitatively recorded as Yes or No. Detailed information on the lesion was displayed in Figure 16D.

Figure 16. Scoring of a sample patient according to the CatLet score algorithm. 

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