Graft Failure After Coronary Artery Bypass Grafting and Its Association With Patient Characteristics and Clinical Events: A Pooled Individual Patient Data Analysis of Clinical Trials With Imaging Follow-Up

Cardiac Surgery 2023 Reviewed

We reviewed the cardiac surgical literature for 2023. PubMed displayed almost 34,000 hits for the search term "cardiac surgery AND 2023." We used a PRISMA approach for a results-oriented summary. Key manuscripts addressed the mid- and long-term effects of invasive treatment options in patient populations with coronary artery disease (CAD), comparing interventional therapy (percutaneous coronary intervention [PCI]) with surgery (coronary artery bypass graft [CABG]). The literature in 2023 again confirmed the excellent long-term outcomes of CABG compared with PCI in patients with left main stenosis, specifically in anatomically complex chronic CAD, but even in elderly patients, generating further support for an infarct-preventative effect as a prognostic mechanism of CABG. For aortic stenosis, a previous trend of an early advantage for transcatheter (transcatheter aortic valve implantation [TAVI]) and a later advantage for surgical (surgical aortic valve replacement) treatment was also re-confirmed by many studies. Only the Evolut Low Risk trial maintained an early advantage of TAVI over 4 years. In the mitral and tricuspid field, the number of interventional publications increased tremendously. A pattern emerges that clinical benefits are associated with repair quality, making residual regurgitation not irrelevant. While surgery is more invasive, it currently generates the highest repair rates and longest durability. For terminal heart failure treatment, donor pool expansion for transplantation and reducing adverse events in assist device therapy were issues in 2023. Finally, the aortic diameter related to adverse events and technical aspects of surgery dominated in aortic surgery. This article summarizes publications perceived as important by us. It cannot be complete nor free of individual interpretation, but provides up-to-date information for patient-specific decision-making.

No-touch saphenous vein: current understanding of the conduit 'less handled'

PURPOSE OF REVIEW

The no-touch technique is an established method to harvest the saphenous vein (NT-SV), which is the most commonly used conduit in coronary artery bypass grafting. Herein, we summarize the foundational evidence, as well as highlight recent innovations and ongoing clinical trials involving NT-SV.

RECENT FINDINGS

Through preservation of perivascular tissue for atraumatic handling and omission of manual distension, the NT-SV maintains endothelial nitrous oxide synthase levels and experiences less vascular smooth muscle cell activation, which translates to slower progression of atherosclerosis and less size mismatch of the graft and target vessel. These biomolecular advantages allow NT-SV to provide superior graft patency compared to conventional skeletonized saphenous vein and approximating that of the radial artery. Nonetheless, the clinical benefits of NT-SV for mortality and reduction in major adverse cardiac and cerebrovascular events are insufficiently studied in the long-term. The drawback of NT-SV is the short-term harvest site complications, which may potentially be addressed by the advent of endoscopic no-touch technique.

SUMMARY

NT-SV is a promising conduit, and its role will be further clarified in upcoming clinical trials and as follow-up lengthens. However, conduit selection and harvest technique should ultimately be personalized to the individual patient.

Statistical primer: individual patient data meta-analysis and meta-analytic approaches in case of non-proportional hazards

Individual patient data (IPD) meta-analyses build upon traditional (aggregate data) meta-analyses by collecting IPD from the individual studies rather than using aggregated summary data. Although both traditional and IPD meta-analyses produce a summary effect estimate, IPD meta-analyses allow for the analysis of data to be performed as a single dataset. This allows for standardization of exposure, outcomes, and analytic methods across individual studies. IPD meta-analyses also allow the utilization of statistical methods typically used in cohort studies, such as multivariable regression, survival analysis, propensity score matching, uniform subgroup and sensitivity analyses, better management of missing data, and incorporation of unpublished data. However, they are more time-intensive, costly, and subject to participation bias. A separate issue relates to the meta-analytic challenges when the proportional hazards assumption is violated. In these instances, alternative methods of reporting time-to-event estimates, such as restricted mean survival time should be used. This statistical primer summarizes key concepts in both scenarios and provides pertinent examples.

One-month DAPT with ticagrelor and aspirin for patients undergoing coronary artery bypass grafting: rationale and design of the randomised, multicentre, double-blind, placebo-controlled ODIN trial

The optimal antiplatelet strategy after coronary artery bypass graft (CABG) surgery in patients with chronic coronary syndromes (CCS) is unclear. Adding the P2Y12 inhibitor, ticagrelor, to low-dose aspirin for 1 year is associated with a reduction in graft failure, particularly saphenous vein grafts, at the expense of an increased risk of clinically important bleeding. As the risk of thrombotic graft failure and ischaemic events is highest early after CABG surgery, a better risk-to-benefit profile may be attained with short-term dual antiplatelet therapy followed by single antiplatelet therapy. The One Month Dual Antiplatelet Therapy With Ticagrelor in Coronary Artery Bypass Graft Patients (ODIN) trial is a prospective, randomised, double-blind, placebo-controlled, international, multicentre study of 700 subjects that will evaluate the effect of short-term dual antiplatelet therapy with ticagrelor plus low-dose aspirin after CABG in patients with CCS. Patients will be randomised 1:1 to ticagrelor 90 mg twice daily or matching placebo, in addition to aspirin 75-150 mg once daily for 1 month; after the first month, antiplatelet therapy will be continued with aspirin alone. The primary endpoint is a hierarchical composite of all-cause death, stroke, myocardial infarction, revascularisation and graft failure at 1 year. The key secondary endpoint is a hierarchical composite of all-cause death, stroke, myocardial infarction, Bleeding Academic Research Consortium (BARC) type 3 bleeding, revascularisation and graft failure at 1 year (net clinical benefit). ODIN will report whether the addition of ticagrelor to low-dose aspirin for 1 month after CABG reduces ischaemic events and provides a net clinical benefit in patients with CCS. (ClinicalTrials.gov: NCT05997693).

Comparative Analysis of Coronary Artery Bypass Grafting Outcomes in Women Using Different Conduits in the National UK Data Set

BACKGROUND

There is limited report of outcomes in women undergoing isolated coronary artery bypass grafting (CABG) with left internal thoracic artery and different second conduits (saphenous vein graft [SVG], radial artery [RA], and right internal thoracic artery [RITA]).

METHODS

The National Adult Cardiac Surgery Audit database was queried for women undergoing isolated CABG with left internal thoracic artery graft in the United Kingdom from 1996 to 2019. Propensity score-based pairwise comparisons were performed between graft types. The primary outcome was in-hospital mortality.

RESULTS

The study included 58,063 women (SVG, n = 48,881 [84.2%]; RA, n = 6136 [10.6%]; RITA, n = 2445 [4.2%]). SVG use was stable over the years; RA and RITA use decreased. In-hospital mortality was similar between the RA and RITA grafts (2.3% vs 2.8%; odds ratio [OR], 0.80; 95% CI, 0.53-1.22; P = .39) and between the RA and SVG (2.3% vs 2.0%; OR, 1.20; 95% CI, 0.93-1.55; P = .17) but higher in the RITA group compared with the SVG (2.7% vs 1.4%; OR, 2.04; 95% CI, 1.27-3.36; P = .004). Women receiving the RITA graft were more likely to have sternal wound infection (SWI) compared with the RA (0.6% vs 0.06%; P = .004) and the SVG (0.6% vs 0.2%; P = .032). SWI was consistently associated with higher risk of in-hospital mortality.

CONCLUSIONS

Conduit selection may affect operative outcomes in women undergoing CABG. The RA shows similar mortality and risk of deep SWI as the SVG.

Thirteen Years of Impactful, Minimally Invasive Coronary Surgery: Short- and Long-Term Results for Single and Multi-Vessel Disease

OBJECTIVES

Minimally invasive coronary surgery (MICS) via lateral thoracotomy is a less invasive alternative to the traditional median full sternotomy approach for coronary surgery. This study investigates its effectiveness for short- and long-term revascularization in cases of single and multi-vessel diseases.

METHODS

A thorough examination was performed on the databases of two cardiac surgery programs, focusing on patients who underwent minimally invasive coronary bypass grafting procedures between 2010 and 2023. The study involved patients who underwent either minimally invasive direct coronary artery bypass grafting (MIDCAB) for the revascularization of left anterior descending (LAD) artery stenosis or minimally invasive multi-vessel coronary artery bypass grafting (MICSCABG). Our assessment criteria included in-hospital mortality, long-term mortality, and freedom from reoperations due to failed aortocoronary bypass grafts post-surgery. Additionally, we evaluated significant in-hospital complications as secondary endpoints.

RESULTS

A total of 315 consecutive patients were identified between 2010 and 2023 (MIDCAB 271 vs. MICSCABG 44). Conversion to median sternotomy (MS) occurred in eight patients (2.5%). The 30-day all-cause mortality was 1.3% (n = 4). Postoperative AF was the most common complication postoperatively (n = 26, 8.5%). Five patients were reoperated for bleeding (1.6%), and myocardial infarction (MI) happened in four patients (1.3%). The mean follow-up time was six years (±4 years). All-cause mortality was 10.3% (n = 30), with only five (1.7%) patients having a confirmed cardiac cause. The reoperation rate due to graft failure or the progression of aortocoronary disease was 1.4% (n = 4).

CONCLUSIONS

Despite the complexity of the MICS approach, the results of our study support the safety and effectiveness of this procedure with low rates of mortality, morbidity, and conversion for both single and multi-vessel bypass surgeries. These results underscore further the necessity to implement such programs to benefit patients.

The Year in Cardiothoracic and Vascular Anesthesia: Selected Highlights From 2023

This special article is the 16th in an annual series for the Journal of Cardiothoracic and Vascular Anesthesia. The authors thank the editor-in-chief, Dr. Kaplan, and the editorial board for the opportunity to continue this series, namely the research highlights of the past year in the specialty of cardiothoracic and vascular anesthesiology. The major themes selected for 2023 are outlined in this introduction, and each highlight is reviewed in detail in the main article. The literature highlights in the specialty for 2023 begin with an update on perioperative rehabilitation in cardiothoracic surgery, with a focus on novel methods to best assess patients in the preoperative and postoperative periods, and the impact of rehabilitation on outcomes. The second major theme is focused on cardiac surgery, with the authors discussing new insights into inhaled pulmonary vasodilators, coronary revascularization surgery, and discussion of causes of coronary graft failure after surgery. The third theme is focused on cardiothoracic transplantation, with discussions focusing on bridge-to-transplantation strategies. The fourth theme is focused on mechanical circulatory support, with discussions focusing on both temporary and durable support. The fifth and final theme is an update on medical cardiology, with a focus on outcomes of invasive approaches to heart disease. The themes selected for this article are only a few of the diverse advances in the specialty during 2023. These highlights will inform the reader of key updates on various topics, leading to improved perioperative outcomes for patients with cardiothoracic and vascular disease.

Multi-slice CT coronary angiography versus invasive coronary angiography in the assessment of graft patency after coronary artery bypasses graft surgery

BACKGROUND

The long-term patency of arterial and venous grafts is crucial for the success of CABG. This study was designed to investigate graft patency using 128-slice coronary computed tomography angiography (CCTA) and compared the results with those obtained using invasive coronary angiography (ICA). In this observational cross-sectional study, we included 40 symptomatic post-CABG patients underwent CCTA and ICA within the same month.

RESULTS

Fifty-five percent were aged more than 60 years, and 80% were males. 67.5% had diabetes, 90% had hypertension, and 30% were smokers. Mean body mass index was 28.89 ± 5.17 kg/m2. Mean duration since CABG was 5.25 ± 4.04 years. In total, 124 native vessels and 97 grafts were assessed using CCTA and ICA. CCTA delineated 8 non-cannulated venous grafts and 6 non-cannulated left internal mammary artery grafts. CCTA required a significantly lower radiation dose (1165.77 ± 123.54 vs. 47,589.78 ± 6967.53, p < 0.001).

CONCLUSION

CCTA can be as accurate as ICA in assessing bypass grafts with less radiation dose, providing a non-invasive reliable tool for evaluation.

Integrative multiomics analysis of neointima proliferation in human saphenous vein: implications for bypass graft disease

Introduction

Human saphenous veins (SV) are widely used as grafts in coronary artery bypass (CABG) surgery but often fail due to neointima proliferation (NP). NP involves complex interplay between vascular smooth muscle cells (VSMC) and fibroblasts. Little is known, however, regarding the transcriptomic and proteomic dynamics of NP. Here, we performed multi-omics analysis in an ex vivo tissue culture model of NP in human SV procured for CABG surgery.

Methods and results

Histological examination demonstrated significant elastin degradation and NP (indicated by increased neointima area and neointima/media ratio) in SV subjected to tissue culture. Analysis of data from 73 patients suggest that the process of SV adaptation and NP may differ according to sex and body mass index. RNA sequencing confirmed upregulation of pro-inflammatory and proliferation-related genes during NP and identified novel processes, including increased cellular stress and DNA damage responses, which may reflect tissue trauma associated with SV harvesting. Proteomic analysis identified upregulated extracellular matrix-related and coagulation/thrombosis proteins and downregulated metabolic proteins. Spatial transcriptomics detected transdifferentiating VSMC in the intima on the day of harvesting and highlighted dynamic alterations in fibroblast and VSMC phenotype and behavior during NP. Specifically, we identified new cell subpopulations contributing to NP, including SPP1 + , LGALS3 + VSMC and MMP2 + , MMP14 + fibroblasts.

Conclusion

Dynamic alterations of gene and protein expression occur during NP in human SV. Identification of the human-specific molecular and cellular mechanisms may provide novel insight into SV bypass graft disease.