Mis-estimation of Coronary Lesions and Rectification by SYNTAX Score Feedback for Coronary Revascularization Appropriateness
Introduction
The decision to perform coronary revascularization, whether through percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG), is heavily influenced by the interpretation of coronary angiograms. However, studies have shown that visual assessment of coronary angiography can lead to mis-estimation of lesion severity, potentially resulting in inappropriate revascularization. For instance, Leape et al. found that imprecise reading of angiograms led to an overestimation of appropriate use of CABG by 17% and PCI by 10%. Although quantitative coronary angiography (QCA) has been developed to address this issue, it only assesses stenosis and lesion length, leaving room for improvement in evaluating overall lesion severity.
The SYNTAX (Synergy Between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery) score is a comprehensive tool designed to evaluate the complexity of coronary lesions based on visual interpretation of angiograms in patients with at least one ≥50% coronary stenosis. Despite its utility, prior studies have noted discrepancies in SYNTAX score calculation between angiographic core laboratories and cardiologists, as well as inter- and intra-observer variability among cardiologists. Such discrepancies can significantly affect therapeutic decisions.
This study hypothesized that real-time SYNTAX score feedback from trained image analysts could rectify mis-estimation of coronary lesion severity and improve the appropriateness of revascularization in patients with stable coronary artery disease (CAD). The study aimed to investigate whether real-time SYNTAX score feedback could reduce inappropriate coronary revascularization and assessed its impact on clinical outcomes.
Methods
Ethical Approval and Study Design
The study protocol was approved by the Institutional Review Board of the National Center for Cardiovascular Diseases in Beijing, China. All eligible patients provided informed consent before undergoing coronary angiography. The study was designed as a single-center, historical control study and was registered at ClinicalTrials.gov. Study recruitment occurred concurrently with an angiographic registry.
Participants
Twelve cardiologists, each with more than 100 PCIs per year, participated in the study. Patients with stable CAD according to the National Cardiovascular Data Registry CathPCI criteria (stable angina, no or silent myocardial ischemia) and at least one coronary lesion stenosis ≥50% based on elective coronary angiography were eligible for inclusion. Exclusion criteria included prior CABG, staged PCI, and revascularization with no corresponding indication in the Chinese Appropriate Use Criteria for coronary revascularization (AUC).
Study Groups and Intervention
Patients were consecutively enrolled in an angiography registry for data collection, which included baseline questionnaires and medical record abstraction. Eligible patients were subsequently enrolled in the SYNTAX score feedback study. From August 2016 to March 2017 (the control period), patients were assigned to the control group, where SYNTAX scores were calculated by treating cardiologists based on visual estimation immediately after coronary angiography. From March 2017 to September 2017 (the intervention period), patients were assigned to the intervention group, where SYNTAX scores were calculated by image analysts immediately after coronary angiography and provided to cardiologists in real-time to aid decision-making. All participating cardiologists maintained autonomy in the decision-making process.
Data Collection
Patients’ demographic, clinical, and procedural characteristics were collected via baseline questionnaires and medical record abstraction. During the control period, cardiologists’ subjective assessments of the SYNTAX score were collected, and the scores were recalculated by image analysts blinded to the patients’ baseline characteristics. During the intervention period, SYNTAX scores were calculated and recorded by the image analysts.
Follow-up Process
All participants were followed up by telephone or mail at 1 year. In the event of reported adverse events, medical records were reviewed for confirmation by independent clinicians.
Outcome Measures
The primary outcome was inappropriate coronary revascularization (PCI or CABG) according to the Chinese AUC for coronary revascularization. Secondary outcomes included inappropriate PCI, inappropriate CABG, PCI utilization, CABG utilization, medical therapy utilization, and major adverse cardiac events (MACE; death from any cause, myocardial infarction, repeat revascularization) throughout the 12-month period after angiography.
Statistical Analysis
Data were presented as mean ± standard deviation for continuous variables and as percentages for discrete variables. Baseline characteristics between the intervention and control groups were compared using Chi-squared or Fisher exact tests for categorical variables and t-tests for continuous variables. Hierarchical logistic regression models and logistic regression models were used to examine the association between SYNTAX score feedback and decision-making, with adjustment for demographic and AUC scenario variables. Multi-variable proportional hazards models were used to calculate hazard ratios and 95% confidence intervals (CIs) for relative risks in relation to the potential impact of confounding factors between SYNTAX score feedback and 1-year outcomes.
Results
Study Participants
A total of 3245 patients were enrolled, with 1525 assigned to the control group and 1720 to the intervention group. Patients in the intervention group were more likely to smoke, have a high Canadian Cardiovascular Society class, and receive no or minimal anti-ischemic medical therapy, and were less likely to have hyperlipidemia.
SYNTAX Score Mis-estimation
Among 1525 patients in the control group, subjective SYNTAX score tertiles assessment was collected from cardiologists for 1233 patients. Cardiologists’ subjective SYNTAX score tertiles assessment were identical to the calculations by the image analysts in 77.8% of patients, underestimated in 4.3% of patients, and overestimated in 17.9% of patients.
Appropriateness and Utilization of Coronary Revascularization
The rate of inappropriate coronary revascularization was lower in the intervention group than in the control group (12.6% vs. 15.7%; unadjusted odds ratio [OR]: 0.77, 95% CI: 0.64–0.94; P = 0.011). This difference persisted after adjusting for patient and cardiologist characteristics (adjusted OR: 0.83, 95% CI: 0.73–0.95; P = 0.007). The intervention group also had reduced odds of inappropriate PCI compared with the control group (unadjusted OR: 0.76, 95% CI: 0.63–0.93; P = 0.008), which remained significant after adjustment (adjusted OR: 0.82, 95% CI: 0.74–0.92; P < 0.001). Additionally, the odds of PCI utilization were lower in the intervention group (adjusted OR: 0.88, 95% CI: 0.79–0.98; P = 0.016). There were no differences in inappropriate CABG or CABG utilization. The odds of medical therapy significantly increased in the intervention group (adjusted OR: 1.18, 95% CI: 1.03–1.36; P = 0.017).
Subgroup Analyses
The effect of SYNTAX score feedback on inappropriate revascularization varied by SYNTAX score tertiles and patient symptomatic status. The score feedback significantly reduced the odds of inappropriate coronary revascularization in patients with low-risk SYNTAX scores (adjusted OR: 0.79, 95% CI: 0.68–0.93; P = 0.004) and those with angina symptoms (adjusted OR: 0.10, 95% CI: 0.01–0.67; P = 0.018). Additionally, the score feedback reduced inappropriate PCI in patients with one-vessel disease (adjusted OR: 0.83, 95% CI: 0.68–0.99, P = 0.049) and angina symptoms (adjusted OR: 0.09, 95% CI: 0.01–0.67; P = 0.018). The score feedback was associated with decreased odds of PCI utilization in patients with low-risk lesions (SYNTAX score 0–22; adjusted OR: 0.83, 95% CI: 0.72–0.95; P = 0.008) and increased odds of PCI utilization in patients with triple-vessel disease (adjusted OR: 1.32, 95% CI: 1.12–1.54; P < 0.001).
One-year Clinical Outcomes
The 1-year follow-up rate was 98.0% in the overall patients. At 1 year, there was no significant difference in MACE, death, myocardial infarction, and repeat revascularization between the intervention and control groups after adjusting for patient characteristics.
Discussion
This study found that SYNTAX score tertiles were overestimated in 17.9% of patients and underestimated in 4.3% of patients. Real-time SYNTAX score feedback by image analysts significantly reduced the risk of inappropriate coronary revascularization in patients with stable CAD, particularly for patients with low-risk lesions (SYNTAX score <23). The score feedback also significantly reduced the rates of inappropriate PCI and PCI utilization, especially for inappropriate PCI in one-vessel lesions and PCI utilization in low-risk lesions (SYNTAX score <23). There was no significant difference in 1-year MACE between the control and intervention groups.
Previous studies have noted the underestimation of SYNTAX scores by cardiologists in patients with three-vessel or left main diseases. However, this study is the first to assess score mis-estimation in all-comer, real-world practice, revealing more overestimation than underestimation. This indicates that overestimation of low-risk or simple lesions should also be noted in clinical practice.
Although the SYNTAX score was primarily recommended for guiding decision-making in patients with complex CAD, this study hypothesized that score feedback could influence decision-making in all-comer CAD patients, including those with one or two-vessel diseases. The results showed that score feedback significantly reduced the risk of inappropriate coronary revascularization, particularly for low-risk lesions (SYNTAX score <23), which were more frequently mis-estimated. This suggests that SYNTAX score feedback rectified cardiologists’ overestimation of lesion complexity, supporting its broader use in clinical practice.
The study also found that score feedback reduced both inappropriate PCI and overall PCI utilization, indicating that cardiologists were better able to recognize patients who would most benefit from revascularization. This represents a valuable strategy to reduce PCI overutilization and increase guideline adherence.
Despite more patients being treated with medical therapy rather than PCI in the intervention group, there was no difference in 1-year outcomes between the control and intervention groups. This result is consistent with the COURAGE and ORBITA trials, which showed no benefit in overall clinical outcomes between patients with stable CAD who underwent PCI and optimal medical therapy. The study’s results suggest that SYNTAX score feedback reduced invasive PCI procedures and saved medical resources without increasing adverse clinical events, further supporting its use for optimal decision-making in patients with stable CAD.
The heart team approach, emphasized by the latest guidelines for optimal decision-making in complex coronary disease, was rarely used in real-world practice. However, this study found that SYNTAX score feedback promoted multi-disciplinary decision-making in patients with complex lesions. The rate of surgical consultation increased in patients with three-vessel or left main coronary disease, and the rate of ad hoc PCI decreased in patients with left main disease. This suggests that SYNTAX score feedback may rectify cardiologists’ underestimation of lesion complexity and encourage interdisciplinary discussion for optimal decision-making.
Ad hoc PCI, although common in clinical practice, is controversial in guidelines. The study found that SYNTAX score feedback significantly decreased inappropriate PCIs, especially in patients with one-vessel disease, who accounted for nearly 60% of ad hoc PCIs. This suggests that SYNTAX score feedback may be particularly valuable for these patients.
Limitations
This study has several limitations. First, it is a single-center, historical control study, not a multi-center, randomized controlled trial. Although confounding factors were adjusted for, the results may not be generalizable to other centers. Second, cardiologist selection bias may influence the outcomes, as all participating cardiologists were experienced operators (>100 PCIs per year). Third, the primary outcome was evaluated using the Chinese AUC rather than the widely known American AUC, which may limit the comparability of the results.
Conclusions
Real-time SYNTAX score feedback by image analysts reduced the proportion of inappropriate coronary revascularization in patients with stable CAD. Both inappropriate PCI and overall PCI utilization also decreased. The score feedback was not associated with 1-year clinical outcomes. SYNTAX score feedback may be a practical approach to improve decision-making regarding coronary revascularization. Further study involving a more diverse pool of cardiologists and centers is warranted.
doi.org/10.1097/CM9.0000000000000827
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