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 >0 and ≤8 and ICR if rSS >8. 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<0.001] 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<0.001]. 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 (Table 1). Table 1: Outcomes at two years of follow-up according to residual SYNTAX score MACE- Major Adverse cardiac event (Cardiac death,MI or Revascularisation); CR- complete revascularization; RICR- Reasonable incomplete revascularization; ICR- Incomplete revascularization   CR (rSS=0) N= 44 RICR (rSS >0 and ≤8) N= 40 ICR (rSS>8) N= 24 P value CR vs RICR p value CR vs ICR P value RICR vs ICR P value All cause death 2 (4.5) 2 (5) 9 (37.5) <0.001 0.92 <0.001 0.001 Cardiac death 1 (2.3) 2 (5) 7 (29.2) 0.001 0.50 0.001 0.007 MI 1 (2.3) 1 (2.5) 8 (33.3) <0.001 0.949 <0.001 0.001 Revascularization 1 (2.3) 3 (7.5) 3 (12.5) 0.25 0.261 0.087 0.51 MACE 2 (4.5) 4 (10) 12 (50) <0.001 0.332 <0.001 <0.001 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.