Percutaneous Coronary Intervention versus Coronary Artery Bypass Grafting for Chronic Total Occlusion of Coronary Arteries: A Systematic Review and Meta-Analysis

Chronic total occlusion (CTO) of coronary arteries, affecting 15-20% of coronary artery disease (CAD) patients, presents a significant clinical challenge. Historically managed with medical management and CABG, advancements in interventional technology have significantly improved PCI success rates, making it a primary treatment option. While PCI for CTO lesions is more challenging than for non-CTO lesions, success rates in experienced centers reach 80-90%. Studies have shown that successful CTO-PCI improves symptoms and quality of life compared to optimal medical therapy (OMT) alone, and is associated with lower mortality, stroke, repeat revascularization, and recurrent angina compared to failed CTO-PCI. However, data on the long-term prognostic impact of CTO-PCI remains limited. This meta-analysis aims to comprehensively compare PCI and CABG outcomes in CTO patients using available cohort studies to address the ongoing controversy surrounding optimal revascularization strategies.

The introduction section provides a comprehensive overview of the existing literature on CTO, PCI, and CABG. It highlights the prevalence of CTO, the challenges associated with PCI for CTO, and the improved success rates achieved in experienced centers due to technological advancements. The review also mentions studies demonstrating the benefits of successful CTO-PCI in symptom relief, quality of life improvement, and reduced short-term adverse events compared to OMT and failed PCI. However, it emphasizes the limited data on the long-term prognostic effects of CTO-PCI, setting the stage for the meta-analysis.

This meta-analysis systematically searched PubMed, Embase, and Web of Science databases (2000-March 2023) for studies comparing PCI and CABG in CTO patients. The search included MeSH terms and keywords like "chronic total occlusion," "percutaneous coronary intervention," "coronary artery bypass grafting," and "revascularization." The study was registered with PROSPERO. Inclusion criteria included studies comparing PCI and CABG outcomes in CTO patients, assessing all-cause mortality, myocardial infarction (MI), cardiac death, repeat revascularization, and MACE. Exclusion criteria included studies comparing successful vs. unsuccessful PCI, studies including patients with other illnesses, studies focusing on only one treatment strategy, and animal studies. Nine studies (8,674 patients) met the inclusion criteria, with a mean follow-up of 4.3 years. Data extraction was performed by two researchers, with discrepancies resolved through discussion. The Newcastle-Ottawa Scale assessed study quality. Weighted risk ratios (RRs) and 95% confidence intervals (CIs) were calculated. Fixed-effects or random-effects models were used depending on heterogeneity (I²). Sensitivity analysis and funnel plots assessed robustness and publication bias. RevMan 5.3 software was used for analysis.

The meta-analysis of 7723 patients showed PCI was associated with a lower incidence of all-cause mortality (RR: 0.78, 95% CI: 0.66-0.92; P < 0.003) and cardiac death (RR: 0.55; 95% CI: 0.31-0.96; P < 0.03) compared to CABG. However, PCI showed a higher incidence of repeat revascularization (RR: 7.42, 95% CI: 5.78-9.53; P < 0.00001). Analysis of six studies revealed no statistically significant difference in MACE between PCI and CABG (RR: 1.11, 95% CI: 0.69-1.81; P = 0.66). Analysis of eight studies showed PCI resulted in a higher incidence of MI compared to CABG, though this difference did not reach statistical significance. Sensitivity analysis showed that results were robust and stable. Funnel plots were used to assess publication bias.

This meta-analysis provides evidence suggesting that PCI is superior to CABG in reducing all-cause mortality and cardiac death in CTO patients. This could be attributed to advancements in interventional techniques, including improved guidewire design, operating techniques, and the use of the J-CTO score. The use of IVUS in PCI has also been shown to improve outcomes. However, the study also found that PCI resulted in higher rates of MI and repeat revascularization. These findings align with results from the BEST and SYNTAX trials. The higher rate of repeat revascularization in the PCI group might be due to the use of IMA grafts in CABG, known for improved long-term patency. The choice of revascularization strategy involves several factors including patient risk profile and physician preference. This study highlights that CABG does not demonstrate clear superiority over PCI in treating CTO, and suggests that PCI may be a favorable option for reducing mortality and cardiac death.

This meta-analysis, the first to specifically compare PCI and CABG outcomes in CTO patients, demonstrates that PCI is superior to CABG in reducing all-cause mortality and cardiac death, but inferior in reducing MI and repeat revascularization. No significant difference in MACE was observed. Further research is needed to define optimal revascularization strategies for CTO patients, considering patient-specific factors and technological advancements.

This meta-analysis has limitations. It did not account for patient-specific factors like ACEF, SYNTAX I, and SYNTAX II scores, which might influence revascularization strategy choice. Heterogeneity among included studies (different follow-up times, clinical outcomes, enrollment criteria) could affect generalizability. The limited number of RCTs and potential influence of non-random factors (patient characteristics, physician preference) might impact results. The number of CTO vessels, potentially affecting outcomes, was not addressed due to lack of data in the original studies.