Abstract
In recent years an angiographic score was introduced in clinical practice to stratified different levels of risk after percutaneous coronary interventions (PCI) with drug eluting stents. The SYNTAX score (SS) classified patients in three different risk levels and was included in revascularization guidelines that patients allocated with low SS could be equally treated with either PCI or CABG, whereas those with intermediate or high SS were better off with CABG. However, using original SS each coronary lesion with a diameter stenosis ≥ 50% in vessels ≥ 1.5 mm was scored.
In ERACI IV registry we used a revascularization strategy during PCI where operators were advised to only treat lesions ≥ than 70% in a ≥ 2.0 mm reference vessel; therefore, no intermediate lesions should be treated, and severe stenosis in vessels < 2.0 mm was discouraged as well.
If we recalculated SS using the above-mentioned operators’ advices all intermediate lesions were not scored, and severe stenosis in vessels < 2.0 mm were excluded for the analysis, including bifurcations, trifurcations and chronic total occlusions; after this new scoring, the original SS dropped significantly which is in accordance with the goal of complete functional revascularization strategy of the ERACI IV study and the low one year adverse events of such study. In conclusion, if we performed an SS scoring, only severe stenosis in vessels with a reference diameter ≥ 2.0 mm would allow a more rational assessment of coronary anatomy, and the use of a more conservative PCI strategy.
Highlights
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The SYNTAX score (SS) was calculated by grading 11 types of lesions and classified patients in three different risk levels: low SS equally treated with PCI or CABG, and intermediate or high and better treated by CABG. However, each coronary lesion with a diameter stenosis ≥ 50% in vessels ≥ 1.5 mm was scored.
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In ERACI IV we modified SS scoring only lesion with a diameter stenosis ≥ 70% and in vessel ≥ of 2 mm. All intermediate lesions or severe lesions in vessel < 2 mm were not scored.
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After this new scoring original SS dropped from 27.7 to 22, and 54.8% of patients had low SS.
In recent years an angiographic score was introduced in clinical practice to stratified different levels of risk after percutaneous coronary interventions (PCI) with drug eluting stents (DES).
Investigators from the SYNTAX trial — which was a randomized comparison between PCI with implantation of a 1st generation DES (Taxus, Express, Boston Scientific, Marlborough, MA, USA) versus coronary artery bypass graft (CABG) in patients with three-vessel coronary artery disease (CAD) or unprotected left main — designed and created an anatomic angiographic score to identified different risk levels in the outcome from those patients included and treated in the SYNTAX trial. This score was called Syntax Score (SS), and almost immediately after SYNTAX trial released the results, SS started being used as a risk score worldwide.
The SYNTAX lesion score was calculated by grading 11 types of lesions, answering sequential interactive questions taking into account: number of disease segments, tortuosity, heavy calcification, presence of thrombus, lesion length, dominance, bifurcation, trifurcation, aorto ostial lesions, diffuse disease, and total occlusion , and each coronary lesion with a diameter stenosis ≥ 50% in vessels ≥ 1.5 mm was scored.
The SS classified patients in three different risk levels: low SS, when they scored 22 or less; intermediate, when they were between 23 and 32; and high when the score was 33 or higher.
Despite the fact that SINTAX was not designed and powered to stratified outcomes with PCI and CABG according to SS, it was concluded that patients allocated with low SS could be equally treated with either PCI or CABG, whereas those with intermediate or high SS were better off with CABG. These findings were rapidly included in revascularization guidelines .
However, this score had some limitations. First, it was only an anatomic score, and functional assessment of lesions during PCI was correlated with better patient outcome . Also, SS did not have any predictive value if patients were treated with CABG; in fact it had no relationship with other risk scores such as Euroscore. Also, since the SS was not validated in other large randomized trials such as FREEDOM , authors from the original paper recently published new SS, adding new clinical and anatomic variables .
The SYNTAX trial was designed to achieve complete anatomic revascularization either with PCI or CABG, therefore all lesions with diameter stenosis larger or equal than 50% in vessels ≥ 1.5 mm should be treated accordingly. In the trial, stent length was 84.6 mm. For the past three years, we conducted a prospective, multicenter, controlled registry called ERACI IV, using a 2nd generation DES (Firebird 2, Microport Inc, Shangai, China) in patients with two or three-vessel CAD and unprotected left main . One year follow-up was recently reported .
In contrast with SYNTAX, in ERACI IV the stent length immediately after PCI was only 41.4 mm in spite of the 27.7 SS shown in the study .
The differences in stent length observed in both studies (86.4 mm vs. 41.4 mm in SYNTAX and ERACI IV respectively, p < 0.001) were not correlated with the differences in SS (p = 0.04), suggesting large variability in PCI strategy. In fact, in ERACI IV, the goal was to achieve complete functional revascularization , and operators were advised to only treat lesions ≥ than 70% in a ≥ 2.0 mm reference vessel, provisional stent in all bifurcations was recommended, no intermediate lesions were treated and, finally, severe stenosis (≥ 70%) in vessels < 2.0 mm was discouraged as well .
Taking into account the original high SS found in ERACI IV, total stent length of this study appears to be quite low, and, for this reason, we recalculated SS now following the above-mentioned operator advice for the study , thus, with these new measures, all intermediate lesions were not scored, and severe stenosis in vessels < 2.0 mm were excluded for the analysis, including bifurcations, trifurcations and chronic total occlusions. In-stent restenosis, allowed to enter in ERACI IV, was scored as heavy calcified lesion; all other angiographic variables were measured according to the original SS. As an example, if a patient had intermediate stenosis (50% to 69%) in a heavy calcified, tortuous and diffuse major epicardial vessel, these angiographic characteristics — which were scored in the original SS — had no value now, within the new assessment, due the presence of an intermediate stenosis. Therefore, all the above-mentioned variables, together with intermediate stenosis, were not scored ( Fig. 1 ).
