Several trials have been conducted comparing coronary artery bypass grafting (CABG) versus percutaneous coronary intervention (PCI) in patients with multi-vessel disease (MVD). CABG has done better mainly because there is a higher rate of revascularization in the percutaneous intervention arm of the studies. One recurring criticism has been that there was no measurable way to take into account the severity or complexity of the CAD. Obviously a patient with left main disease involving the ostium of the left anterior descending artery (LAD) and circumflex is a higher risk than a patient with mid right coronary artery (RCA), mid LAD and mid circumflex lesions. Yet both would be considered 3VD.

The SYNTAX Score was developed for use in the SYNTAX (SYNergy between PCI with TAXus and cardiac surgery) trial.1 It is lesion-based (limit 12 lesions) and each lesion can have one or more segments (no limit).

The score is calculated via a computer program. You enter each lesion and answer questions, of which there are twelve. The program totals the score for each lesion and then calculates a SYNTAX score. The higher the score, the more complex the lesions, and risk. The score takes into account total occlusions, age of TO, side branches, ostial and aorto stenosis, bifurcations, trifurcation, calcified lesions, thrombus, length of lesion, tortuosity, and diffuse disease.

As my own facility looks at implementing this score, I find myself asking:

How will the SYNTAX Score impact the cardiac cath lab, the interventional cardiologists and the surgeons? Who is going to be responsible for entering the data used to calculate the score? Should it be cath lab staff in the room at the time of the diagnostic procedure? Should it be only physicians entering the information? Should it be only one person?

Are the results of the score going to impact volume for interventions and surgery? Patients who have a low to medium score and have left main or three-vessel disease can have percutaneous interventions. Does this mean that many patients who previously would have gone for CABG are now gong to be treated with multivessel stenting in the cath lab? And, if so, how is acuity of patients and length of procedures in the lab going to be impacted? Radiation exposure and contrast volumes are sure to increase — how will this alter patient outcomes?

Challenges include:

• Many of the questions are yes or no; for example, is the lesion heavily calcified? All individuals are not going to answer this question the same, even though they are looking at the same artery.

• Each data element in the scoring has specific criteria and definitions. It will be imperative that the person doing the data is knowledgeable about these so the score accurately reflects the lesion complexity.

In the future, perhaps the program could be linked to the actual images of the arteries and automatically score each lesion, thereby eliminating the human error possibilities. Regardless, it seems that the SYNTAX Score, when completed accurately, could become acceptable standard guidelines to determine a patient’s treatment.

Reference
1. Sianos G, Morel MA, Kappetein AP, et al. The SYNTAX Score: an angiographic tool grading the complexity of coronary artery disease. EuroIntervention 2005:219-227.