Quantification and impact of untreated coronary artery disease after percutaneous coronary intervention: the residual SYNTAX (Synergy Between PCI with Taxus and Cardiac Surgery) score

Abstract

Objectives: The purpose of this study was to quantify the extent and complexity of residual coronary stenoses following percutaneous coronary intervention (PCI) and to evaluate its impact on adverse ischemic outcomes.

Background: Incomplete revascularization (IR) after PCI is common, and most studies have suggested that IR is associated with a worse prognosis compared with complete revascularization (CR). However, formal quantification of the extent and complexity of residual atherosclerosis after PCI has not been performed.

Methods: 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 IR and were stratified by rSS tertiles, and their outcomes were compared to the CR group.

Results: 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 to 1.09, p = 0.006).

Conclusions: The rSS is useful to quantify and risk-stratify the degree and complexity of residual stenosis after PCI. Specifically, rSS >8.0 after PCI in patients with moderate- and high-risk ACS is associated with a poor 30-day and 1-year prognosis. (Comparison of Angiomax Versus Heparin in Acute Coronary Syndromes; NCT00093158).

Figure 1. Correlation Between bSS and rSS

Relationship between the baseline SYNTAX score (bSS) (x-axis) and the residual SYNTAX score (rSS) (y-axis) after percutaneous coronary intervention in 2,686 patients. Each point may represent more than 1 value. A strong correlation was present between bSS and rSS, although for any level of bSS, the range of post-PCI rSS varied considerably. SYNTAX = Synergy Between Percutaneous Coronary Intervention With Taxus and Cardiac Surgery.

Figure 2. Completeness of Revascularization Stratified by rSS According to bSS

Distribution of level of completeness of revascularization stratified by rSS score according to bSS score. Complete revascularization was infrequent in the 2 upper tertiles of the bSS. Abbreviations as in Figure 1.

Figure 3. Kaplan-Meier Curves Showing Cumulative Event Rates Through 1 Year

(A) MACE, (B) death, (C) myocardial infarction, and (D) unplanned revascularization, stratified by tertiles of rSS score. Adverse ischemic events were significantly higher in incomplete revascularization compared with complete revascularization groups and across all the rSS tertiles. Abbreviations as in Figure 1.

Figure 4. Kaplan-Meier Curves Showing Cumulative Death Rate Through 1 Year

One-year cumulative death rate for each level of completeness of revascularization stratified by true tertiles of baseline SS. Low risk, 0 to 7 (A); intermediate risk, >7 to 13 (B); and high risk, >13 (C). In the intermediate- and high-risk tertiles, incomplete revascularization with rSS >8 was associated with greater mortality than complete revascularization. Abbreviations as in Figure 1.