Reasonable incomplete revascularisation after percutaneous coronary intervention: the SYNTAX Revascularisation Index

Incomplete revascularisation is common after percutaneous coronary intervention (PCI). While the absolute amount of residual coronary artery disease (CAD) after PCI has been shown to be associated with worse outcomes, whether the proportion of treated CAD is prognostically important remains to be determined. We sought to quantify the proportion of CAD burden treated by PCI and to evaluate its impact on outcomes using a new prognostic instrument - the SYNTAX Revascularisation Index (SRI).The baseline SYNTAX score (bSS) and residual SYNTAX score (rSS) were determined from 2,618 angiograms of patients enrolled in the prospective ACUITY trial. The SRI was then calculated for each patient using the following formula: SRI=(1-[rSS/bSS])×100. Outcomes were examined according to three SRI groups (SRI=100% [complete revascularisation], 50-99%, and <50%). The median bSS was nine (IQR 5, 16), and after PCI the median rSS was one (IQR 0, 6). The median SRI was 85% (IQR 50, 100), and was 100% in 1,079 patients (41.2%), 50-99% in 907 patients (34.6%), and <50% in 632 patients (24.1%). One-year adverse outcomes, including death, were inversely proportional to the SRI. An SRI cut-off of <80% (present in 1,189 [45.4%] patients after PCI) had the best prognostic accuracy for prediction of death (area under the curve 0.60, 95% confidence interval [CI]: 0.53-0.67, p<0.0001). By multivariable analysis, SRI was an independent predictor of one-year mortality (hazard ratio [HR] 2.17, 95% CI: 1.05-4.35, p=0.03). However, when compared to other scores, the rSS showed superior accuracy and predictive capability for one-year mortality.The SRI is a newly described method for quantifying the proportion of CAD burden treated by PCI. Given its correlation with mortality, and pending external validation, the SRI may be useful in assessing the degree of revascularisation after PCI, with SRI ≥80% representing a reasonable goal. However, the rSS showed superior predictive capability for one-year mortality.