Quantification and Impact of Untreated Coronary Artery Disease After Percutaneous Coronary Intervention: The Residual SYNTAX (Synergy Between PCI With Taxus and Cardiac Surgery) Score

Study Questions:

What is the impact of the extent and complexity of residual coronary stenoses following percutaneous coronary intervention (PCI) on adverse ischemic outcomes?


The baseline Synergy Between PCI With Taxus and Cardiac Surgery (SYNTAX) score (bSS) from 2,686 angiograms from patients with moderate- and high-risk acute coronary syndrome (ACS) undergoing PCI enrolled in the prospective ACUITY (Acute Catheterization and Urgent Intervention Triage Strategy) trial was determined. The SS after PCI was also assessed, generating the “residual” SS (rSS). Patients with rSS >0 were defined as having incomplete revascularization (IR) and were stratified by rSS tertiles, and their outcomes were compared to the complete revascularization (CR) group.


The bSS was 12.8 ± 6.7, and after PCI, the rSS was 5.6 ± 2.2. Following PCI, 1,084 patients (40.4%) had rSS = 0 (CR), 523 (19.5%) had rSS >0 but ≤2, 578 (21.5%) had rSS >2 but ≤8, and 501 patients (18.7%) had rSS >8. Age, insulin-treated diabetes, hypertension, smoking, elevated biomarkers or ST-segment deviation, and lower ejection fraction were more frequent in patients with IR compared with CR. The 30-day and 1-year rates of ischemic events were significantly higher in the IR group compared with the CR group, especially those with high rSS. By multivariable analysis, rSS was a strong independent predictor of all ischemic outcomes at 1 year, including all-cause mortality (hazard ratio, 1.05; 95% confidence interval, 1.02-1.09; p = 0.006).


The authors concluded that the rSS is useful to quantify and risk-stratify the degree and complexity of residual stenosis after PCI.


This study suggests that in moderate- and high-risk ACS patients with IR following PCI, the newly described rSS may be an independent predictor of 1-year mortality, cardiac mortality, myocardial infarction, and unplanned revascularization. The rSS has a good discriminatory power for risk prediction of 1-year ischemic outcomes, and may be a useful tool to stratify the extent and complexity of residual coronary stenoses after PCI, and identify patients who could benefit from further revascularization. Additional prospective randomized trials are required to further evaluate the clinical importance of the rSS score before its use in clinical practice.

Clinical Topics: Acute Coronary Syndromes, Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention, Prevention, Aortic Surgery, Interventions and ACS, Interventions and Coronary Artery Disease, Hypertension, Smoking

Keywords: Acute Coronary Syndrome, Myocardial Infarction, Coronary Artery Disease, Coronary Disease, Angioplasty, Balloon, Coronary, Smoking, Percutaneous Coronary Intervention, Coronary Stenosis, Cardiology, Catheterization, Cardiac Surgical Procedures, Hypertension, Diabetes Mellitus

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