Main Findings
In this observational study, we identified that the incidence of all-cause death, stroke, or MI in patients with LMCAD undergoing either PCI or CABG was similar, even in those with a high SS I. Additionally, the rates of MI and repeat revascularization were significantly higher in the PCI group, corroborating the NOBLE trial’s results15.
The original SYNTAX trial suggested CABG as the preferable method for patients with LMCAD with high SS I16,17. Technological advancements, such as new drug coatings for DES and thinner metallic platforms18, have improved stent design, reducing the rate of in-stent restenosis and target lesion revascularization.
Moreover, the prevalent use of intravascular imaging, such as IVUS or OCT, has improved PCI outcomes17,19,20. The success of PCI for LMCAD relies on thorough pre-procedural planning, correct stent apposition, optimal stent expansion, and appropriate wire positioning during rewiring. Both IVUS20–22 and OCT23,24 can provide valuable information when performing PCI for LMCAD. Our cohort reported that 89.1% of patients undergoing PCI for LMCAD used intravascular imaging, higher than the 77.2% reported in the EXCEL trial25. Current guidelines recommend IVUS for LMCAD as a Class IIA intervention26.
These advancements in PCI techniques and technology have improved clinical outcomes, a conclusion supported by the results of the SYNTAX II study27. This progress also allows for a greater likelihood of complete revascularization, further improving clinical outcomes28. In our study, most patients in the PCI group received DES (96.5%), all of which were second-generation or third-generation DES. This contemporary PCI approach for patients with LMCAD might explain the comparable short-term and mid-term outcomes between the PCI and CABG groups. As such, the applicability of only using the SS I to guide decision making on revascularization is questionable. It is noteworthy that real-world data show the advancements have made PCI an alternative choice for patients with LMCAD and high SS I29. Moreover, clinical factors such as diabetes or EuroSCORE were more relevant to outcomes instead of the SS I30.
Likewise, the mean SS I was 32.0 ± 11.6 in our study and 45.5% of patients had high SS I (SS I ≥ 33), supported PCI as a reasonable choice in high anatomical complexity cases who are ineligible for CABG.
Regarding the SS II 2020, the predicted 5-year MACE rates with PCI/CABG were both significantly higher in our PCI group than in the CABG group. This observation may reflect the fact that patients with a high risk may prefer PCI over CABG or even were not suitable for CABG after heart team evaluation.
Nevertheless, the PCI group had higher risks for MI and repeat revascularization, aligning with prior research27,31–33. Among the eight patients experiencing MI in the PCI group of our study, five incidents related to target lesion revascularization (TLR). In contrast, the CABG group reported a markedly lower MI rate. PCI primarily addresses flow-limiting lesions, but further events may occur due to either target lesions or non-target lesions. With CABG treatment, graft vessels usually bypass the entire disease vessels which might help avert future MI events34. Beside the diseased part of the target vessel, previous study suggested left internal mammary artery (LIMA) grafting was associated with lower risk of down-stream disease progression compared to PCI35. The EXCEL trial also confirmed significantly higher non-periprocedural MI rates in the PCI group compared with the CABG group at five years (6.8% vs. 3.5%)3.
In our cohort, most patients in the PCI group underwent repeat revascularization non-emergently, often for non-left main lesions. The risk of repeat revascularization and TLR did not vary between high and low to intermediate SS I group (supplementary table S3). Furthermore, we suggest implementing standardized postoperative care after revascularization (PCI or CABG) in future studies due to potential disparities in postoperative care among surgeons and interventionalists.
The SS II and SS II 2020 incorporate clinical factors to predict long-term outcomes after revascularization. In our study, SS II recommendations did not significantly discriminate the risk of MACE in the PCI group. Similarly, a cut off value of ARD ≥ 4.5% or < 4.5% calculated from the SS II 2020 did not associate with MACE. These observations may be influenced by a limited sample size without adequate statistical power. In addition, we used categorical variables rather than the absolute estimated mortality in this study, which limited the prognostic prediction. Patients with high estimated mortality in both PCI and CABG could be classified as equipoise in SS II and as ARD < 4.5% in SS II 2020, although their prognosis was expected to be poorer. The utility of SS II 2020 warrants further evaluation.
We acknowledge that our study, being retrospective and observational, may have inherent limitations, including potential selection bias and confounding factors. Periprocedural MI was not included due to debates over its definition after revascularization. Clinical events were obtained by reviewing medical records without formal adjudication.