1. The revalidated SYNTAX score II 2020 was effective at predicting 10-year all-cause mortality in patients undergoing percutaneous coronary intervention (PCI) vs. coronary artery disease bypass graft (CABG).
2. The SYNTAX score II 2020 proved effective at predicting major cardiovascular events (all-cause death, non-fatal stroke, non-fatal myocardial infarction) 5-years post-procedure.
Evidence Rating Level: 2 (Good)
Study Rundown: As one of healthcare’s most studied topics, myocardial revascularization benefits from a robust history of predictive models and algorithms. The Synergy Between PCI with TAXUS and Cardiac Surgery (SYNTAX) study was one such landmark study that compared CABG procedures with PCI in patients with de-novo three-vessel disease, left main coronary artery disease, or both. While subgroup analyses in these predictive models may be helpful, they are often limited in scope due to their inability to consider many important clinical considerations. Multivariable risk predictive models, on the other hand, address this shortcoming by account for many variables at once. This study was based off of the SYNTAX and SYNTAXES trials, which were multicenter, randomized controlled trial comparing outcomes from CABG vs. PCI in 1800 patients. Using the data obtained with the SYNTAX trial, researchers constructed a multivariate predictive model that could estimate 10-year all-cause mortality and 5-year major cardiovascular adverse events in patients undergoing CABG or PCI with good consistency. Overall, there was no difference at 10-years in all-cause mortality in either group. When externally validated with other trials studying treatment of patients with coronary artery disease, the SYNTAX score II 2020 showed excellent predictive ability in both determining 10-year all-cause mortality, and 5-year major cardiovascular event risk. An important consideration of this trial is that the original SYNTAX study was performed with medical technology that would now be considered outdated. Given that sufficient contemporary data is not available for the development of new multivariate models, this is a necessary shortcoming. Ultimately, however, the strong predictive efficacy and objectivity of this model places it in good standing to be used as one tool among many in clinical decision-making for patients with complex coronary artery disease.
In-Depth [randomized controlled trial]: This extension follow-up of a multicenter, randomized controlled trial utilized data from 1800 patients randomized to either PCI or CABG treatment between March 2005 and April 2007. Patients with triple-vessel or left main coronary artery disease who had a clinical equipoise between PCI or CABG were randomly assigned to either intervention. This data was extrapolated to create a multivariate predictive model capable of estimating all-cause 10-year mortality, an important and robust clinical endpoint for clinicians, as well as 5-year major cardiovascular events. The SYNTAX score II 2020 utilized data from this patient group, comparing the result of their model to other large studies of patients with coronary artery disease as external validation. The predictive model consisted of the prognostic index (includes age, creatinine clearance, left ventricular ejection fraction, smoking status, medically treated-diabetes, receipt of insulin, COPD, and peripheral vascular disease), initial revascularization strategy (PCI vs. CABG), and two treatment interactions (three-vessel disease or left main coronary artery disease and anatomical SYNTAX score). At 10 years post-procedure, there was no significant difference in mortality between the PCI and CABG groups (hazard ratio [HR] = 1.19 [95% CI 0.99-1.43], log-rank p value=0.066). At 5 years, however, patients in the CABG group experienced significantly fewer major adverse cardiovascular events (HR = 1.27 [95% CI 1.02-1.59], log-rank p value =0.030). Additionally, CABG was found to have favourable outcomes in patients with three-vessel disease (HR = 0.67 [95% CI 0.53-0.86]), but not those with left main coronary artery disease (HR = 1.02 [95% CI 0.77-1.36], pinteraction=0.028). The model showed good discriminative ability in determining 10-year mortality (concordance index=0.73 [95% CI 0.69-0.76] for PCI and 0.73 [0.69-0.76] for CABG) as well as for major cardiovascular adverse events (concordance-index=0.67 [95% CI 0.63-0.70] for PCI and 0.62 [95%CI 0.58-0.66] for CABG). Overall, the prognostic performance of the SYNTAX score II 2020 was significantly better than the performance of their previous model, the SYNTAX score II.
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