From a Position of Known Angiographic Perfect Patency: What Happens Next?

BACKGROUND AND AIM

The biological behaviour of coronary graft conduits over time may be considered by serial angiography.

METHODS

A single institution retrospective cohort received mostly clinically indicated angiography between 1997 and 2020, following coronary bypass surgery. Only perfectly patent grafts (absence of any lumen irregularity) for each conduit type at the first postoperative angiogram were selected for a later comparison. The latest angiograms were at least 5 years postoperatively, and at least 1 year after first postoperative angiogram. Analysis was done according to each graft (anastomosis). Comparisons used generalised estimating equations, adjusted for binary logistic regression.

RESULTS

Of 143 patients, there were 410 of 468 (87.6%) perfectly patent grafts at the first angiogram, analysed at 6.8±4.0 years postoperative, of which 157 were internal mammary arteries, 228 were radial arteries, and 25 were saphenous veins. At the latest angiogram (12.2±3.8 years postoperative), comparison with the first angiogram for each individual graft found preserved perfect patency for internal mammary arteries, 156 of 157 (99.4%), and for radial arteries, 227 of 228 (99.6%) but saphenous veins deteriorated considerably, 13 of 25 (52.0%). The two arterial grafts (internal mammary and radial) were superior to vein grafts (odds ratio 163; 95% confidence interval [CI] 22-1,211; p<0.001), but not different from each other (odds ratio 0.95; 95% CI 0.78-1.16; p=0.584).

CONCLUSIONS

From a position of known angiographic perfect patency post-CABG, internal mammary artery and radial artery grafts retained their perfect patency in the longer term, but saphenous vein grafts did not.

Twenty-year outcomes of free and I-composite radial artery grafts for coronary artery revascularization

PURPOSE

To compare the 20-year outcomes of coronary artery grafting (CABG) using radial artery (RA) grafts (free and I-composite) and internal thoracic artery (ITA) grafts.

METHODS

Long-term graft patency was evaluated in patients who underwent isolated CABG between August, 1996 and January, 2022. The long-term graft patency of free RA grafts, I-composite ITA-RA grafts, and saphenous vein (SV) grafts were compared.

RESULTS

The RA was used as a coronary bypass conduit in 111 of the 246 patients enrolled in this study. The RA patency after 10 and 20 years was 94.2% and 76.6%, respectively. Landmark analysis showed that although graft patency for up to 10 years did not differ between the RA and ITA grafts (hazard ratio = 0.87; P = 0.8), patency of the ITA grafts was better from 10 to 20 years post-surgery (hazard ratio = 0.19; P = 0.013). The 20-year graft patency of the I-composite RA grafts was better than that of the free RA grafts (80.0% vs. 72.4%; P = 0.029), but not significantly different from that of the ITA grafts (80.0% vs. 90.7%; P = 0.24).

CONCLUSIONS

The 20-year patency of the I-composite ITA-RA graft was better than that of the free RA graft; therefore, the I-composite graft may be an effective conduit for CABG.

The use of free versus in situ right internal mammary artery in coronary artery bypass grafting

INTRODUCTION

Coronary artery bypass grafting (CABG) continues to be the most commonly performed cardiac surgical procedure in the world. The use of multiarterial grafting may confer a long-term survival benefit over the use of vein grafts. However, there is a paucity of data comparing the use of in situ versus free right internal mammary artery (RIMA) in isolated CABG.

METHODS

Patients that underwent isolated CABG between 2010 and 2018 where RIMA was used in addition to a left internal mammary artery graft. Patients with prior cardiac surgery or percutaneous coronary intervention were excluded. Propensity matching was used for subanalysis. Mortality and major adverse cardiac and cerebrovascular events (MACCE) were analyzed with Kaplan-Meier survival curves and Cox multivariable regression. Heart failure-specific readmissions were assessed with cumulative incidence curves with Fine and Gray competing risk regression.

RESULTS

A total of 667 patients underwent isolated CABG. Of those, 422 had free RIMA and 245 had in situ RIMA utilized. Mortality was similar between cohorts (p = 0.199) with 5-year mortality rates of 6.6% (free) and 4.1% (in situ). MACCE was similar between cohorts, with 5-year event rates of 33.6% and 33.9% (p = 0.99). RIMA style was not a significant predictor of any outcome.

CONCLUSION

There was no difference in long-term mortality, complications, MACCE, or heart failure readmissions when comparing a contemporary cohort of patients undergoing isolated CABG utilizing RIMA as a conduit. These data may allow surgeons to consider using RIMA either as an in situ or a free conduit.

The Risk Factor Analysis for the Late Graft Failure of Radial Artery Graft in Coronary Artery Bypass Grafting

Objective: The aim of this retrospective study was to investigate the early operative results and detect the factors influencing the fate of radial artery grafts (RAGs) by evaluating the mid-term patency.

Methods: We retrospectively reviewed 410 patients who underwent isolated coronary artery bypass grafting using RAG. RAGs were anastomosed to 526 coronary arteries. Mid-term angiography was performed in 214 patients at an average 4.9 years after the operation.

Results: The early patency of RAGs was 97.6%. Cumulative 5-year patency was 86.5% for RAG, 94.1% for LITA graft, and 81.0% for saphenous vein graft (SVG). RAG was significantly superior to SVG in mid-term patency. Individual grafting (not sequential grafting) (hazard ratio [HR]: 2.535; 95% confidence interval [CI]: 1.293–5.281; p = 0.006) and grafting to the target coronary artery with ≤75% proximal stenosis (HR: 1.947; 95% CI: 1.090–3.484; p = 0.025) were found to be independent risk factors influencing late RAG patency.

Conclusions: The patency of RAGs was superior to that of SVGs in the studied population. When using RAGs, grafting to the target vessel with severe proximal stenosis is favorable. The RAG is suitable for sequential grafting.

Strategies for the coronary surgeon to remain "competitive and co-operative" in the PCI era

BACKGROUND

The advent of percutaneous intervention has made surgical treatment of coronary artery disease less favored by patients though the evidence that supports CABG in certain patient subsets is strong.

METHODS

Literature review was done using Pubmed, Scopus, Google and Google Scholar with MeSH terms-coronary artery bypass grafting, internal mammary artery, drug eluting stent, stroke, myocardial revascularization.

RESULTS

The adoption of evolving techniques like anaortic off pump grafting, bilateral internal mammary artery use, hybrid and minimally invasive coronary revascularization techniques, intra-operative graft assessment, and heart team approach can lead to better outcomes following surgery as is evidenced by recent literature.

CONCLUSIONS

Though the adoptability of the newer strategies may vary between centers a close coalition between coronary surgeons and cardiologists would ensure that the management of coronary artery disease is based on evidence for the benefit of the patient.

Cells and stimuli in small-caliber blood vessel tissue engineering

The absence of successful solutions in treatments of small-caliber vessel diseases led to the Vascular Tissue Engineering approach to develop functional nonimmunogenic tissue engineered blood vessels. In this context, the choice of cells to be seeded and the microenvironment conditioning are pivotal. Biochemical and biomechanical stimuli seem to activate physiological regulatory pathways that induce the production of molecules and proteins stimulating stem cell differentiation toward vascular lineage and reproducing natural cross-talks among vascular cells to improve the maturation of tissue engineered blood vessels. Thus, this review focuses on (1) available cell sources, and (2) biochemical and biomechanical stimuli, with the final aim to obtain the long-term stability of the endothelium and mechanical properties suitable for withstanding physiological load.

Graft pathology at the time of harvest: impact on long-term survival

Objective

This study aims to present the graft pathology at the time of harvest and its impact on long-term survival.

Methods

The remnants of the bypass grafts from 66 consecutive patients with coronary artery disease receiving a coronary artery bypass grafting were investigated pathologically, and pertinent predictive risk factors and survival were analyzed.

Results

Medial degenerative changes with or without intimal proliferation were present in 36.8%, 37.8% and 35.6% of left internal mammary artery (IMA), radial artery and saphenous vein grafts. There were 2 (3.0%) hospital deaths and 9 (14.1%) late deaths. Multinomial logistic regression revealed left IMA pathological changes, dyslipidemia, history of percutaneous transluminal coronary angioplasty/stent deployment and Y-graft were significant predictive risk factors negatively influencing the patients’ long-term survival. Kaplan-Meier survival analysis revealed that the long-term survival of patients with left IMA pathological changes were significantly reduced compared with those without (74.1% vs. 91.4%, P=0.002); whereas no differences were noted in long-term survivals between patients with and without pathological changes of the radial arterial or saphenous vein grafts.

Conclusion

Pathological changes may be seen in the bypass graft at the time of harvest. The subtle ultrastructural modifications and the expressions of vascular tone regulators might be responsible for late graft patency. The pathological changes of the left IMA at the time of harvest rather than those of the radial artery or saphenous vein graft affect significantly longterm survival. Non-traumatic maneuver of left IMA harvest, well-controlled dyslipidemia and avoidance of using composite grafts can be helpful in maintaining the architecture of the grafts.

Mid-Term Patency in Radial Artery and Saphenous Vein After Coronary Artery Bypass Grafting in Asymptomatic Patients Using 128-Slice CT Coronary Angiography

Background:

Patency of the revascularization conduit is an essential predictor of long-standing survival after coronary artery bypass grafting.

Objectives:

We have conducted this study to compare the mid-term patency rates of radial artery (RA), left internal thoracic artery (LITA) and also saphenous vein (SV) grafts in asymptomatic patients following coronary artery bypass graft surgery (CABG) undergoing total IV anesthesia.

Patients and Methods:

In this study, 30 three-vessel disease patients with 104 RA, LITA, and SV grafts used concomitantly for primary isolated non-emergent CABG surgery were assessed. The primary end point was CT angiographic graft patency rate. After 53.5 (24-97) months’ follow-up, graft patency was assessed using 128-slice CT coronary angiography. Logistic regression analysis was used to detect the independent predictors of graft failure.

Results:

A total of 104 grafts, including 30 LITA, 44 SV, and 30 RA grafts, were studied. Cumulative graft patency rates were 93.3% in LITA, 83.3% in RA, and 70.5% in SV grafts. Statistically significant difference was found between the LITA and the SV graft patency rates (P = 0.019), whereas the difference between the RA conduit patency and the LITA or SV graft patency rates did not have any statistical significance (P = 0.424 and P = 0.273, respectively). Independent predictors of RA grafts occlusion were native coronary stenosis < 70% and female gender.

Conclusions:

In our patients, the RA grafts had an acceptable patency rate in 2 to 5 years’ follow-up. Although the SV grafts had a relatively higher patency rate than RA grafts in our asymptomatic patients, the patency rates in RA and SV grafts were close to each other. The RA graft function was poor in the patients with a higher number of risk factors and in the females.

Novel potential targets for prevention of arterial restenosis: insights from the pre-clinical research

Restenosis is the pathophysiological process occurring in 10-15% of patients submitted to revascularization procedures of coronary, carotid and peripheral arteries. It can be considered as an excessive healing reaction of the vascular wall subjected to arterial/venous bypass graft interposition, endarterectomy or angioplasty. The advent of bare metal stents, drug-eluting stents and of the more recent drug-eluting balloons, have significantly reduced, but not eliminated, the incidence of restenosis, which remains a clinically relevant problem. Biomedical research in pre-clinical animal models of (re)stenosis, despite its limitations, has contributed enormously to the identification of processes involved in restenosis progression, going well beyond the initial dogma of a primarily proliferative disease. Although the main molecular and cellular mechanisms underlying restenosis have been well described, new signalling molecules and cell types controlling the progress of restenosis are continuously being discovered. In particular, microRNAs and vascular progenitor cells have recently been shown to play a key role in this pathophysiological process. In addition, the advanced highly sensitive high-throughput analyses of molecular alterations at the transcriptome, proteome and metabolome levels occurring in injured vessels in animal models of disease and in human specimens serve as a basis to identify novel potential therapeutic targets for restenosis. Molecular analyses are also contributing to the identification of reliable circulating biomarkers predictive of post-interventional restenosis in patients, which could be potentially helpful in the establishment of an early diagnosis and therapy. The present review summarizes the most recent and promising therapeutic strategies identified in experimental models of (re)stenosis and potentially translatable to patients subjected to revascularization procedures.

Nitric oxide and the CABG patient

The post surgery success of coronary artery bypass grafting (CABG) is counteracted by thrombosis and de-endothelialization, intimal hyperplasia and, over the long term, atherosclerosis. There are many reasons to assume that in CABG patients vascular bioavailability of NO generated by the endothelium plays an important role for graft function. This holds true for factors such as graft type, harvesting and storage, the type of surgery, non-pharmacologic prevention of risk factors, for example, regular physical activity (if feasible), and drug therapy. Although the precise role of graft endothelial NO bioavailability for graft patency and clinical endpoints is still uncertain, current data rather speak in favor of NO indicating that the potential of vasoprotective activities of NO in the CABG patient deserves further investigation.