The Use of Intraoperative Transit Time Flow Measurement for Coronary Artery Bypass Surgery: Systematic Review of the Evidence and Expert Opinion Statements.

Transit time flow measurement (TTFM) allows quality control in coronary artery bypass grafting but remains largely underused, probably because of limited information and the lack of standardization. We performed a systematic review of the evidence on TTFM and other methods for quality control in coronary artery bypass grafting following PRISMA standards and elaborated expert recommendations by using a structured process. A panel of 19 experts took part in the consensus process using a 3-step modified Delphi method that consisted of 2 rounds of electronic voting and a final face-to-face virtual meeting. Eighty percent agreement was required for acceptance of the statements. A 2-level scale (strong, moderate) was used to grade the statements based on the perceived likelihood of a clinical benefit. The existing evidence supports an association between TTFM readings and graft patency and postoperative clinical outcomes, although there is high methodological heterogeneity among the published series. The evidence is more robust for arterial, rather than venous, grafts and for grafts to the left anterior descending artery. Although TTFM use increases the duration and the cost of surgery, there are no data to quantify this effect. Based on the systematic review, 10 expert statements for TTFM use in clinical practice were formulated. Six were approved at the first round of voting, 3 at the second round, and 1 at the virtual meeting. In conclusion, although TTFM use may increase the costs and duration of the procedure and requires a learning curve, its cost/benefit ratio seems largely favorable, in view of the potential clinical consequences of graft dysfunction. These consensus statements will help to standardize the use of TTFM in clinical practice and provide guidance in clinical decision-making.

Arterial Grafts for Coronary Bypass: A Critical Review After the Publication of ART and RADIAL.

Observational and randomized evidence shows that arterial grafts have better patency rates than saphenous vein grafts (SVGs) in coronary artery bypass grafting. Observational studies suggest that the use of multiple arterial grafts is associated with longer postoperative survival, but this must be interpreted in the context of treatment allocation bias and hidden confounders intrinsic to the study designs. Recently, a pooled analysis of 6 randomized trials comparing the radial artery with the SVG as the second conduit and the largest randomized trial comparing the use of single and bilateral internal thoracic arteries have provided apparently divergent results about a clinical benefit with the use of >1 arterial conduit. However, both analyses have methodological limitations that may have influenced their results. At present, it is unclear whether the well-documented increased patency rate of arterial grafts translates into clinical benefits in the majority of patients undergoing coronary artery bypass grafting. A large randomized trial testing the arterial grafts hypothesis (ROMA [Randomized Comparison of the Clinical Outcome of Single Versus Multiple Arterial Grafts]) is underway and will report the results in a few years.

Impact of preoperative fractional flow reserve on arterial bypass graft anastomotic function: the IMPAG trial.

AIMS: Visual estimation is the most commonly used method to evaluate the degree of coronary artery stenosis prior to coronary artery bypass grafting. In interventional cardiology, the use of fractional flow reserve (FFR) to guide revascularization decisions has become routine. We investigated whether the preoperative FFR measurement of coronary lesions is associated with anastomosis function 6 months after surgical revascularization using a multiarterial grafting strategy. METHODS AND RESULTS: In this prospective double-blind study, 67 patients were enrolled from two institutions in Europe and Canada. From these patients, 199 coronary lesions were assessed visually and with FFR at the time of the preoperative angiogram. All patients received coronary revascularization using multiple arterial grafts. A post-operative 6-month angiogram was performed to assess anastomosis functionality using a described angiographic method. The primary outcome was the association between preoperative FFR values and anastomosis function 6 months after surgery. Preoperative FFR was significantly associated with 6-months anastomotic function for all conduits and for all targets (P < 0.001). An FFR value of ≤0.78 was associated with an anastomotic occlusion rate of 3%. CONCLUSION: We found a significant association between the preoperative FFR measurement of the target vessel and the anastomotic functionality at 6 months, with a cut-off of 0.78. Integration of FFR measurement into the preoperative diagnostic workup before multiarterial coronary surgical revascularization leads to improved anastomotic graft function. CLINICAL TRIALS. GOV IDENTIFIER: NCT02527044.

Myocardial Revascularization Trials.

This article reviews the context and evidence of recent myocardial revascularization trials that compared percutaneous coronary intervention with coronary artery bypass grafting for the treatment of left main and multivessel coronary artery disease. We develop the rationale that some of the knowledge synthesis resulting from these trials, particularly with regard to the claimed noninferiority of percutaneous coronary intervention beyond nondiabetic patients with low anatomic complexity, may have been affected by trial design, patient selection based on suitability for percutaneous coronary intervention, and end point optimization favoring percutaneous coronary intervention over coronary artery bypass grafting. We provide recommendations that include holding a circumspect interpretation of the currently available evidence, as well as suggestions for the collaborative design and conduct of future clinical trials in this and other fields.

Mechanisms, Consequences, and Prevention of Coronary Graft Failure.

Graft failure occurs in a sizeable proportion of coronary artery bypass conduits. We herein review relevant current evidence to give an overview of the incidence, pathophysiology, and clinical consequences of this multifactorial phenomenon. Thrombosis, endothelial dysfunction, vasospasm, and oxidative stress are different mechanisms associated with graft failure. Intrinsic morphological and functional features of the bypass conduits play a role in determining failure. Similarly, characteristics of the target coronary vessel, such as the severity of stenosis, the diameter, the extent of atherosclerotic burden, and previous endovascular interventions, are important determinants of graft outcome and must be taken into consideration at the time of surgery. Technical factors, such as the method used to harvest the conduits, the vasodilatory protocol, the storage solution, and the anastomotic technique, also play a major role in determining graft success. Furthermore, systemic atherosclerotic risk factors, such as age, sex, diabetes mellitus, hypertension, and dyslipidemia, have been variably associated with graft failure. The failure of a coronary graft is not always correlated with adverse clinical events, which vary according to the type, location, and reason for failed graft. Intraoperative flow verification and secondary prevention using antiplatelet and lipid-lowering agents can help reducing the incidence of graft failure.

Three Arterial Grafts Improve Late Survival: A Meta-Analysis of Propensity-Matched Studies.

BACKGROUND: Little evidence shows whether a third arterial graft provides superior outcomes compared with the use of 2 arterial grafts in patients undergoing coronary artery bypass grafting. A meta-analysis of all the propensity score-matched observational studies comparing the long-term outcomes of coronary artery bypass grafting with the use of 2-arterial versus 3-arterial grafts was performed. METHODS: A literature search was conducted using MEDLINE, EMBASE, and Web of Science to identify relevant articles. Long-term mortality in the propensity score-matched populations was the primary end point. Secondary end points were in-hospital/30-day mortality for the propensity score-matched populations and long-term mortality for the unmatched populations. In the matched population, time-to-event outcome for long-term mortality was extracted as hazard ratios, along with their variance. Statistical pooling of survival (time-to-event) was performed according to a random effect model, computing risk estimates with 95% confidence intervals. RESULTS: Eight propensity score-matched studies reporting on 10 287 matched patients (2-arterial graft: 5346; 3-arterial graft: 4941) were selected for final comparison. The mean follow-up time ranged from 37.2 to 196.8 months. The use of 3 arterial grafts was not statistically associated with early mortality (hazard ratio, 0.93; 95% confidence interval, 0.71-1.22; P=0.62). The use of 3 arterial grafts was associated with statistically significantly lower hazard for late death (hazard ratio, 0.8; 95% confidence interval, 0.75-0.87; P<0.001), irrespective of sex and diabetic mellitus status. This result was qualitatively similar in the unmatched population (hazard ratio, 0.57; 95% confidence interval, 0.33-0.98; P=0.04). CONCLUSIONS: The use of a third arterial conduit in patients with coronary artery bypass grafting is not associated with higher operative risk and is associated with superior long-term survival, irrespective of sex and diabetic mellitus status.

Percutaneous coronary intervention versus coronary artery bypass grafting: where are we after NOBLE and EXCEL?

PURPOSE OF REVIEW: The publication of the NOBLE and EXCEL trials, with seemingly conflicting results, brought into question whether percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG) is better for low-risk patients with left main coronary artery stenosis (LMCAS). This review appraises the methods and results of NOBLE and EXCEL, contextualizes them within the literature, and determines how they may affect clinical practice. RECENT FINDINGS: We appraised the trials and describe differences in methodology and results. NOBLE recruited primarily isolated LMCAS, and found that CABG was superior to PCI. EXCEL's population included patients LMCAS in the context of multivessel CAD, and found PCI and CABG were comparable. Both trials enrolled young patients with few comorbidities, and there was more protocol-mandated consistency in the procedural techniques and medical therapy of patients receiving PCI. SUMMARY: The generalizability of these trials is limited by the use of young, healthy patients at highly skilled centres that rarely reflect typical clinical practice. If these studies are to maintain relevance, trialists must address the lack of protocolization of surgical interventions and inconsistent medical therapies. Unfortunately, the limitations of NOBLE and EXCEL mean that we are no closer to answering the question of what is the optimal treatment for patients with LMCAS.

Clampless versus clamped coronary bypass grafting: does it make a difference?

PURPOSE OF REVIEW: The techniques of coronary artery bypass grafting (CABG) have evolved remarkably over the last two decades since the introduction of off-pump coronary artery bypass (OPCAB). This article focuses on the clinical outcomes of 'clampless' CABG strategies, that include OPCAB with a partial clamp, OPCAB with a proximal suture device, and aorta no-touch OPCAB. RECENT FINDINGS: Observational studies have shown the superiority of OPCAB for preventing strokes and pulmonary complications. Conversely, recent large-scale randomized controlled trials (RCTs) have been unable to demonstrate the benefits of OPCAB. Because of these differing results across numerous studies, the debate about the overall superiority of OPCAB versus on-pump CABG remains controversial. However, the literature regarding the OPCAB technique with minimized manipulation of the aorta suggests this has likely benefits, especially for high-risk patients. SUMMARY: Previous large RCTs did not focus on specific approaches of OPCAB or the importance of the experience of surgeons and institutions, and so further studies are needed. Observational studies and meta-analyses have indicated that improved outcomes can be achieved by applying specific OPCAB approaches according to each patient's characteristics.

Left main coronary stenosis: surgery still reigns.

PURPOSE OF REVIEW: Coronary artery bypass grafting (CABG) has been regarded as the mainstream treatment for unprotected left main coronary artery (ULMCA) stenosis. However, the results of the Evaluation of XIENCE versus Coronary Artery Bypass Surgery for Effectiveness of Left Main Revascularization (EXCEL) trial, in which percutaneous coronary intervention (PCI) was deemed noninferior to CABG, have raised a question whether the guidelines should be changed. This article provides a critical appraisal of recent randomized control trials (RCTs) on ULMCA stenosis. RECENT FINDINGS: In contrast to EXCEL trial, another large RCT named the Nordic-Baltic-British Left Main Revascularization trial showed that PCI is inferior to CABG in patients treated for ULMCA stenosis. The reason for the discrepancy between these two RCTs may be due to differences in study design. In EXCEL trial, the adoption of new periprocedural myocardial infarction definition, the noninclusion of target vessel revascularization as a primary endpoint component, and the timeline of the study may have helped claim that PCI is noninferior to CABG. SUMMARY: The long-term efficacy of PCI for ULMCA stenosis has not yet been demonstrated. Further studies and follow-up data are needed before the indications for PCI are expanded in this scenario.

Bilateral internal thoracic artery graft configuration and coronary artery bypass grafting conduits.

PURPOSE OF REVIEW: Bilateral internal thoracic arteries (BITAs) have demonstrated their superiority over all other types of graft in terms of patency and survival benefit. BITA implementation requires the surgeon's evaluation of the patient's coronary anatomy and demographics. There is no single ideal approach to BITA utilization, but instead a variety of configurations that can be implemented based on the patient characteristics. RECENT FINDINGS: This article details the advantages and disadvantages of several BITA configurations in the setting of left-sided myocardial revascularization and right-sided myocardial revascularization. Different BITA configurations will be described and will ultimately serve as a guide to avoiding technical difficulties and helping surgeons construct decision-making trees to direct the implementation of BITA grafts. SUMMARY: BITA grafting provides long-term clinical benefit over conventional grafting. Efforts should be directed toward a more efficient use of internal thoracic arteries, reducing the need for a third complementary graft, and toward identification of the best alternative to the saphenous vein graft as the third graft material for complete revascularization. Surgeons should ask their cardiologists to be as accurate as possible regarding the severity of the coronary lesion. If the severity of the lesion is not obvious upon an informal qualitative assessment, a functional flow reserve of the lesion should be performed, in order to identify the optimal graft.

Operative mortality with coronary artery bypass graft: where do we stand in 2015?

PURPOSE OF REVIEW: Coronary artery bypass graft (CABG) surgery has evolved and become much safer since its inception. This article outlines recent strategies in optimizing CABG mortality. RECENT FINDINGS: Improving operative mortality around CABG relates to five components. These include the role of relevant quality indicators; improved CABG techniques, such as multiple arterial grafting with less manipulation of the aorta; improvements in cardiopulmonary bypass; refinements in cardiac anaesthesia along with postoperative care; and the development of centres of excellence. SUMMARY: The development of advanced surgical revascularization techniques raises the question as to whether CABG expertise should be considered a sub-specialty of cardiac surgery. An expert CABG surgeon should be able to appropriately utilize several different revascularization techniques to adjust the operation to the patient, rather than the contrary.

Mitral Valve Repair is Feasible Following Extensive Decalcification and Reconstruction of the Atrioventricular Groove.

BACKGROUND AND AIM OF THE STUDY: Mitral annular calcification (MAC) represents a significant challenge in mitral valve (MV) surgery. Techniques to decalcify the mitral annulus significantly increase operative complexity and risk. MV repair can be particularly difficult in this setting. Mid-term outcomes following MV surgery with extensive annular decalcification were examined, with attention focused on the feasibility and outcomes of MV repair in this setting. METHODS: Among 1,485 patients undergoing MV surgery between 1999 and 2008 at the authors' institutions, 24 (1.6%) underwent complete posterior MV annular decalcification associated with either MV repair (n = 19) or replacement (n = 5). Extensive decalcification was performed from commissure to commissure in all patients. The annulus was reconstructed with pledgeted compression sutures in 17 patients, and with a bovine pericardial patch in seven. RESULTS: In-hospital mortality was 12.5%. One patient died in the operating room from atrioventricular groove rupture, and two patients died from low cardiac output postoperatively. During a mean follow up of 4.4 ± 2.7 years, eight patients died; five of these deaths were cardiovascular in nature. After five years the actuarial survival was 56 ± 11%, and freedom from cardiac death 63 ± 11%. Four patients underwent' reoperation because of failure of MV repair (n = 2), endocarditis (n = 1) or hemolysis (n = 1). All survivors were in NYHA class ≤ 2, with none to trivial mitral regurgitation in all MV repairs. The five-year freedom from MV reoperation was 82 ± 8%. CONCLUSION: After aggressive decalcification of the posterior MV annulus, both MV repair and replacement were feasible, with acceptable procedure-related mortality. It was clear however, that decalcification increased both complexity and risk. In well-selected patients, an aggressive approach to MV repair might facilitate a high rate of repair with acceptable midterm outcome in this patient population.

Total Arterial Revascularization: Evaluating the Length of the Radial Artery in a Composite Graft Configuration.

PURPOSE: Reimplanting the radial artery in the left internal thoracic artery as a composite graft allows total arterial revascularization (TAR) without aortic manipulation. The limitation of this strategy is the length of the radial artery required to reach distal right coronary artery (RCA) branches. Our analysis focuses on the feasibility of this strategy. METHODS: A total of 169 patients underwent TAR using the radial artery in a composite grafting configuration. Length of the radial artery, number of sequential anastomoses, heart size, target location, length of the arm, patient height, body surface area, and flow in the composite graft were prospectively collected. RESULTS: The mean length of the radial artery was 18.02 cm. Patients with a mean length of the radial artery of 15.9 cm needed an extension of the radial artery with another conduit to reach the RCA distal branches. When T-configuration is used, the length of the radial artery should be 0.53 cm per sequential anastomosis to reach the RCA distal branches. CONCLUSIONS: Our study shows that an average length of 18.02 cm of radial artery is needed to reach targets on the RCA distal branches in composite grafting. In T-configuration, we need 0.53 cm more length per anastomosis to achieve TAR.

Cerebral embolization during percutaneous valve implantation does not occur during balloon inflation valvuloplasty: prospective diffusion-weighted brain MRI study.

BACKGROUND AND AIM OF THE STUDY: The study aim was to define the timing of cerebral embolization events during transcatheter aortic valve implantation (TAVI), and to determine if events were more closely associated with valve implantation or with balloon inflation. METHODS: Between January 2008 and November 2011, a total of 114 patients underwent TAVI at the author's institution. Of these patients, 44 had previously undergone imaging before and after TAVI, and were included in the study (26 transfemoral (TF); 18 transapical (TA)). Eleven patients who had only balloon valvuloplasty (BV) during the same period were included, as were 22 patients who had open aortic valve replacement (AVR), as controls. All 77 patients underwent neurological examination, and all had cerebral MRIs before and after their procedures. RESULTS: Fifty of the 77 patients who underwent postprocedural MRI had new cerebral lesions, as follows: 24/26 (92%) in TF patients; 17/18 (94%) in TA patients; 3/11 (27%) in BV patients; and 6/22 (27%) in AVR patients (TF and TA versus BV and AVR, p < 0.0001). The mean number and volume of embolic lesions per patient were respectively 5.4/438 mm3 for TF, 11.6/3414 mm3 for TA, 0.7/46 mm3 for BV, and 0.4/48 mm3 for AVR (TF versus TA and BV versus AVR, p = NS; TF and TA versus BV and AVR, p < 0.0001). No association was found between either the EuroSCORE or patient age and the number of events. CONCLUSION: In the present study, an incidence of silent cerebral embolic lesions after TAVI was identified which was significantly higher than that for BV or AVR. This indicated an association of embolism with valve implantation rather than with balloon inflation.

Fibrinogen concentration significantly decreases after on-pump versus off-pump coronary artery bypass surgery: a systematic point-of-care ROTEM analysis.

OBJECTIVES: Studies have emphasized the importance of normal fibrinogen concentrations in surgical patients. The primary hypothesis of this study was that fibrinogen levels significantly decrease in on-pump coronary artery bypass graft (CABG) surgery versus off-pump coronary artery bypass graft (OPCAB) surgery. The second objective was to show that ROTEM (TEM International, GmbH, Munich, Germany) rapidly detects these abnormalities compared with standard tests. DESIGN: A prospective, nonrandomized study. SETTING: A university hospital. PARTICIPANTS: Forty-two and 62 patients in the CABG and OPCAB groups, respectively, undergoing first-time bypass surgery were included. INTERVENTIONS: CABG versus OPCAB surgery. MEASUREMENTS AND MAIN RESULTS: Routine coagulation tests and ROTEM values were measured before anesthesia (T0), after the first dose of heparin (T1), after protamine (T2), upon intensive care unit arrival (T3), and 4 hours postoperatively (T4). The outcome measures were followed until 4 hours postoperatively. Fibrinogen concentrations were significantly lower in the CABG versus the OPCAB group at T2 (170 ± 44 v 243 ± 73 mg/dL, p < 0.001) and T3 (179 ± 42 v 232 ± 68 mg/dL, p < 0.001). This was confirmed by significantly lower FIBTEM maximal clot firmness values at T2 (9 ± 4 v 14 ± 5 mm, p < 0.001) and T3 (9 ± 4 v 13 ± 6 mm, p < 0.001). In the CABG group, patients received significantly more transfusions of all blood products except fresh frozen plasma. CONCLUSIONS: Fibrinogen concentration significantly decreases after cardiopulmonary bypass. ROTEM helps in its fast detection.

Long-term survival, cardiovascular, and functional outcomes after minimally invasive coronary artery bypass grafting in 566 patients.

OBJECTIVE: Sternotomy has been the gold standard incision for surgical revascularization but may be associated with chronic pain and sternal malunion. Minimally invasive coronary artery bypass grafting allows for complete surgical revascularization through a small thoracotomy in selected patients. There is a paucity of long-term data, particularly functional outcomes, for patients who underwent minimally invasive coronary artery bypass grafting. METHODS: Patients (N = 566) who underwent minimally invasive coronary artery bypass grafting at a single institution over a 17-year period were prospectively followed. The primary outcome was survival. At late follow-up, patients were contacted for a questionnaire on functional outcomes. Multivariable Cox proportional hazard model identified correlates of the primary outcome. RESULTS: Clinical follow-up was complete for 100% of patients (mean 7.0 ± 4.4 years); a follow-up questionnaire was also completed for 83.9% (N = 427) of live patients. Fifty percent of patients (N = 283) had undergone multivessel grafting. At 12 years, survival for the entire cohort was 82.2% ± 2.6%. On late follow-up questionnaire, 12 patients (2.8%) had greater than Canadian Cardiovascular Score Class II angina and 19 patients (4.5%) had greater than New York Heart Association Class II symptoms. More than 98% of patients did not have pain related to the incision site. Cox proportional hazards analysis identified older age, peripheral vascular disease, prior myocardial infarction, left ventricular dysfunction, cancer in the past 5 years, intraoperative transfusion, and hybrid revascularization as correlates of mortality during follow-up. CONCLUSIONS: Minimally invasive coronary artery bypass grafting is a safe and durable alternative to sternotomy coronary artery bypass grafting in selected patients, with excellent short- and long-term outcomes, including for multivessel coronary disease. At long-term follow-up, the proportion of patients with significant symptoms and incisional pain was low.

Competitive flow in coronary bypass surgery: is it a problem?

PURPOSE OF REVIEW: Competition flow is a common finding in arterial grafting. This phenomenon can lead to graft occlusion. RECENT FINDINGS: Internal thoracic arteries are the best equipped arterial conduit to withstand the competition flow thanks to their endothelial function. Radial as well as right gastroepiploic arteries support much less flow competition because of their different anatomy, histology and endothelial function than that of internal thoracic artery, leading to spasm and occlusion. Therefore, these two arterial conduits should be used only in case of critical lesion to avoid graft occlusion. Saphenous vein graft is the only conduit that is not significantly affected by flow competition, mainly because of its nonresistivity and common reimplantation in the aorta. Graft configuration is the second important factor influencing the equation between graft flow and native coronary flow. Therefore, composite grafting should be reserved for the case of severely stenotic coronary target, especially if multiple arterial sequential anastomoses have to be performed on the lateral-inferior wall of the heart. Finally, an accurate tool such as the fractional flow reserve to evaluate the stenosis severity should be the milestone of coronary surgery in order to decrease the rate of flow competition and improve arterial grafting functionality. CONCLUSION: Competition flow plays a crucial role in arterial grafting functionality. Grafting strategy should address this by appropriate graft choice and configuration in order to avoid graft attrition.

An increase in endogenous erythropoietin concentrations has no cardioprotective effects in patients undergoing coronary artery bypass graft surgery.

OBJECTIVE: Preliminary data showed an increase in endogenous erythropoietin (EPO) concentrations after acute normovolemic hemodilution (ANH) in patients undergoing coronary artery bypass graft (CABG) surgery. Numerous studies have shown the organ protective properties of EPO. The aim of this study was to investigate the cardioprotective effects of these increased EPO concentrations that resulted from ANH during cardiac surgery. DESIGN: A prospective, randomized, blind study. SETTING: A university hospital. PARTICIPANTS: A total of 93 patients undergoing isolated CABG surgery with or without cardiopulmonary bypass (CPB). INTERVENTIONS: Subjects with CPB were randomized into the control (C) or ANH group. Those in the off-pump coronary artery bypass group underwent no treatment. In the ANH group, a precalculated amount of blood was withdrawn and replaced by colloids after the induction of anesthesia. MEASUREMENTS AND MAIN RESULTS: Hemodynamic parameters were recorded intra- and postoperatively. Troponin concentrations were measured as a routine parameter postoperatively. Upon intensive care unit arrival, the EPO levels were higher in the ANH group than in the C group. There was no significant difference between the troponin values of the C and the ANH groups at 4 hours postoperatively. CONCLUSIONS: In patients undergoing CABG surgery on CPB, an increase in endogenous EPO concentrations in the physiologic range has no cardioprotective effects.