A quantification and impact of incomplete revascularization using residual syntax score in NSTEMI patients after percutaneous coronary intervention

Objectives: The aim of this study was to assess the prognostic significance of rSS after PCI for NSTEMI in terms of all-cause mortality and MACE (Major adverse cardiac event) at 3 years of follow-up.Methodology: A retrospective analysis of 115 consecutive NSTEMI patients who underwent PCI at the Aga Khan University Hospital Karachi between January 2016 and December 2016 was performed. 7 patients were excluded from the final analysis due to missing data (n=108). The SYNTAX scores before (baseline syntax=bSS) and after PCI (rSS) were calculated. Patients were stratified as CR if rSS =0, RICR if rSS \u3e0 and ≤8 and ICR if rSS \u3e8.Results: Patients that achieved CR were 44 (40.7%), RICR were 40 (37.7%) and ICR were 24 (22.2%). After three-year follow-up, ICR patients had the highest incidence of both all-cause mortality [(CR) 4.5% vs. (RICR) 5% vs. (ICR) 37.5% respectively; p\u3c0.001] and major adverse cardiovascular (MACE) defined as composite of follow up cardiac death, MI and revascularization [(CR) 5% vs. (RICR) 10% vs. (ICR) 50% respectively; p\u3c0.001]. There was no difference in the incidence of all-cause death (4.5% vs. 5%; p=0.92) or MACE (4.5% vs 10%, p=0.332) in patients with CR and ICR respectively.Conclusion: The residual SYNTAX score (rSS) is a useful tool in quantifying incomplete revascularization in patients undergoing PCI for NSTEMI. ICR appears to confer a higher three-year mortality and MACE, however outcomes for RICR and CR were comparable. Hence the calculation of rSS in daily practice may also be used to determine a reasonable level of revascularization in patients where complete revascularization may not be possible