Validation of SYNTAX Score II 2020 for CABG vs. PCI in CAD Patients
- Although randomized controlled trials have deemed CABG and PCI ‘equivalent’ treatment options for patients with multivessel CAD, some patients may be better candidates for one treatment over another.
- SYNTAX score II 2020 aims to individualize risks and benefits of revascularization strategies (CABG vs. PCI) for patients with multivessel disease.
Can the SYNTAX score II be redefined to predict the benefit of coronary artery bypass grafting (CABG) vs. percutaneous coronary intervention (PCI) over a 10-year period?
The SYNTAX Extended Survival (SYNTAXES) study is an investigator-driven extension follow-up of a multicenter, randomized controlled trial done in 85 hospitals across 18 North American and European countries between March 2005 and April 2007. Patients with de novo three-vessel and left main coronary artery disease (CAD) were randomly assigned (1:1) to either the PCI group or CABG group. The SYNTAXES study ascertained 10-year all-cause deaths. They used Cox regression to develop a clinical prognostic index for predicting death over a 10-year period, which was combined, in a second stage, with assigned treatment (PCI or CABG) and two prespecified effect-modifiers, which were selected on the basis of previous evidence: disease type (three-vessel disease or left main CAD) and anatomical SYNTAX score.
They used similar techniques to develop a model to predict the 5-year risk of major adverse cardiovascular events (defined as a composite of all-cause death, nonfatal stroke, or nonfatal myocardial infarction) in patients receiving PCI or CABG. The investigators then assessed the ability of these models to predict the risk of death or a major adverse cardiovascular event, and their differences (i.e., the estimated benefit of CABG vs. PCI by calculating the absolute risk difference between the two strategies) by cross-validation with the SYNTAX trial (n = 1,800 participants) and external validation in the pooled population (n = 3,380 participants) of the FREEDOM, BEST, and PRECOMBAT trials. The concordance (C)-index was used to measure discriminative ability, and calibration plots were used to assess the degree of agreement between predictions and observations.
At cross-validation, the newly developed SYNTAX score II, termed SYNTAX score II 2020, showed a helpful discriminative ability in both treatment groups for predicting 10-year all-cause deaths (C-index = 0.73 [95% confidence interval, 0.69–0.76] for PCI and 0.73 [0.69–0.76] for CABG) and 5-year major adverse cardiovascular events (C-index = 0.65 [0.61–0.69] for PCI and C-index = 0.71 [0.67–0.75] for CABG). At external validation, the SYNTAX score II 2020 showed helpful discrimination (C-index = 0.67 [0.63–0.70] for PCI and C-index = 0.62 [0.58–0.66] for CABG) and good calibration for predicting 5-year major adverse cardiovascular events. The estimated treatment benefit of CABG over PCI varied substantially among patients in the trial population, and the benefit predictions were well calibrated.
The SYNTAX score II 2020 for predicting 10-year deaths and 5-year major adverse cardiovascular events can help to identify individuals who will benefit from either CABG or PCI, thereby supporting heart teams, patients, and their families to select optimal revascularization strategies.
The SYNTAX score II 2020 contains eight prognostic factors (age, diabetes, insulin use, creatinine clearance, left ventricular ejection fraction, chronic obstructive pulmonary disease, peripheral vascular disease, current smoker) and two effect modifiers (three-vessel disease vs. left main only disease and anatomical SYNTAX score). Findings from this impressive study aim to refine which patients may benefit from PCI versus CABG based on their individual risk. With the SYNTAX score II 2020, there is personalization of treatment recommendations which move away from both treatment options being equal (based on randomized controlled trial results) to which of the treatment options may be better for a given patient.
Keywords: Cardiac Surgical Procedures, Coronary Artery Bypass, Coronary Artery Disease, Myocardial Infarction, Myocardial Revascularization, Percutaneous Coronary Intervention, Risk Assessment, Stroke
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