Asian Cardiovasc Thorac Ann 2008;16:164-178
© 2008 Asia Publishing EXchange Ltd
Current Status of Off-pump Coronary Artery Bypass Surgery
Shahzad G Raja, MRCS,
Gilles D Dreyfus, PhD1
Glasgow Royal Infirmary, Glasgow
1 Harefield Hospital, Harefield, United Kingdom
For reprint information contact: Shahzad G Raja, MRCS, Tel: 44 141 211 4503, Fax: 44 141 211 4845, Email: drrajashahzad{at}hotmail.com, Glasgow Royal Infirmary, Department of Cardiac Surgery (Ward 65), Queen Elizabeth Building, Alexandra Parade, Glasgow, G31 2ER, Scotland, United Kingdom.
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ABSTRACT
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The expanding indications for angioplasty coupled with the successful short and mid-term results of randomized controlled trials of drug-eluting stents have already had an unquestionable impact on the practice of coronary revascularization operations. However, coronary artery bypass grafting remains a major mode of therapy for coronary artery disease. It is likely that surgery will continue to be preferred for more complex subsets and that surgeons will have to continue to maintain good results in patients with more complex problems. Concerns regarding morbidity associated with conventional surgical myocardial revascularization on cardiopulmonary bypass have led to a resurgence of interest in off-pump bypass surgery during the last decade, with the expectation that it would be safer if cardiopulmonary bypass could be avoided. This review summarizes the impact of off-pump bypass surgery in reducing the morbidity and mortality associated with conventional coronary artery bypass on cardiopulmonary bypass by evaluating the current best-available evidence from randomized controlled trials and meta-analyses comparing off-pump surgery with conventional bypass grafting.
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INTRODUCTION
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Trials comparing percutaneous coronary intervention and coronary artery bypass grafting (CABG) in patients deemed candidates for either procedure have found no significant difference in the rates of death or myocardial infarction during follow-up.1–7 However, repeat revascularization is required more frequently after percutaneous coronary interventions with or without the use of stents.8 Prior to the development of drug-eluting stents, patients with multivessel coronary artery disease requiring revascularization would often undergo CABG rather than a percutaneous intervention because of concern about the likelihood of restenosis. Other factors such as left main coronary artery disease, diabetes mellitus and technical feasibility also influenced the decision to proceed with CABG.8–10
Although CABG performed with cardiopulmonary bypass (CPB), owing to less frequent need for repeat revascularization or re-intervention, has become a well-established treatment modality for patients with coronary artery disease, there is increasing evidence that CPB may be responsible for some of the morbidity associated with CABG. The systemic inflammatory reaction initiated by the extracorporeal circuit results in mechanical trauma to blood, activation of various immunological cascades (complement, cytokines), impaired hemostasis, neurological, renal and gastrointestinal dysfunction.11 Furthermore, aortic cannulation, cross clamping and CPB can result in microembolization and macroembolization, with subsequent neurological and other end-organ injury, including global myocardial ischemia/reperfusion injury.12 Recently, short and mid-term results of randomized controlled trials (RCTs) comparing drug-eluting stents with bare metal stents have shown significant reductions in the incidence of instent restenosis with drug-eluting stents.13–24 These encouraging results coupled with the less invasive nature of percutaneous coronary techniques and the concerns regarding CPB associated morbidity have led to a decline in referral for surgical myocardial revascularization and prompted surgeons to undertake off-pump coronary artery bypass (OPCAB) in the hope that CABG would be safer if CPB could be avoided. Off-pump coronary artery bypass is currently the focus of scientific scrutiny and a vast amount of research related to this technique has been reported.25 We are currently practicing in an era of evidence-based medicine where double-blinded RCTs have been allotted the highest level of evidence.26 This review summarizes the current best-available evidence from RCTs and meta-analyses to assess the status of OPCAB as a safe technique for myocardial revascularization.
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METHODS
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SEARCH METHODOLOGY
MEDLINE, EMBASE, the Cochrane Controlled Trials Register, Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects, Science Citation Index, Current Contents, NHS Economic Evaluation Database, and the International Network of Agencies for Health Technology Assessment databases were searched from the date of their inception to the first week of May 2005 using Medical Subject Headings (MeSH) search terms "off-pump coronary artery bypass", "coronary artery bypass surgery", "beating heart coronary artery bypass", and the non-MeSH search term "minimally invasive direct coronary artery bypass (MIDCAB)". Searching was undertaken in accordance with the Cochrane Collaboration recommendations to identify all published randomized trials comparing OPCAB with conventional CABG.27 English and non-English language articles were included. Tangential electronic exploration of related articles and hand searches of bibliographies, scientific meeting abstracts and related journals were also performed.
INCLUSION CRITERIA
All blinded or unblinded RCTs comparing OPCAB or MIDCAB on the beating heart with conventional CABG on CPB using cardioplegic arrest, recruiting adult patients undergoing single or multivessel bypass and reporting at least one pertinent clinical or economic outcome were included. Studies reporting outcomes of hybrid (OPCAB plus balloon angioplasty) procedures, robotically assisted surgery or those using circulatory assist devices were excluded.
DATA EXTRACTION AND VALIDATION OF STUDIES
The papers found by the search strategy were appraised in a structured format using critical appraisal checklists. These are widely available in several formats and aid in assessing the paper for methodological and analytical soundness, and help to uncover any significant methodological flaws.28 The following information was extracted from each study: first author, year of publication, study population characteristics, selection and exclusion criteria, number of patients operated on with each technique and key outcomes. Finally, for each outcome or aspect of OPCAB evaluated, a conclusion was formulated based on the validity of the studies identified, taking into consideration the source and strength of the evidence using the grading system proposed by the Centre for Evidence-Based Medicine (Table 1
).29
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RESULTS
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Seventy RCTs fulfilling the inclusion criteria were retrieved for evaluation after screening 3,389 citations.30–99 One paper reported pooled analysis of two trials.55 Most RCTs had a selection bias toward lower-risk cases. Only the trial by Carrier and colleagues49 recruited high-risk patients with at least 3 of the following risks: age > 65 years, high blood pressure, diabetes, serum creatinine > 2.0 mg•dL–1, ejection fraction < 45%, pulmonary disease, unstable angina, congestive heart failure, repeat bypass surgery, anemia and significant carotid atherosclerosis. Most other RCTs excluded high-risk patients. The trials by Puskas and colleagues48 and Legare and colleagues50 recruited a patient population that was more representative of current CABG practice, although these also excluded emergency procedures (requiring immediate surgery), concomitant major cardiac procedures, ejection fraction < 30% and reoperation. In addition, 4 meta-analyses and 3 systematic reviews were also retrieved.100–106
Several large case series have suggested a morbidity benefit, cost benefit, reduced length of hospitalization and even mortality benefit for patients undergoing beating-heart CABG compared with CABG performed with CPB.50 More recent retrospective studies, using more sophisticated statistical tools such as case matching and propensity score analysis, have also suggested that beating-heart surgery is associated with decreased morbidity manifested by reductions in transfusion requirements, infection, length of hospitalization, renal failure and encephalopathy as well as mortality.107–113 However, in the hierarchy of clinical evidence, the RCT is generally considered the best approach to ascertain the value of a particular therapy.114 The current best-available evidence from RCTs was systematically used to assess the impact of OPCAB on systemic inflammation, organ damage, quality of life and graft patency.
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IMPACT ON SYSTEMIC INFLAMMATION
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Cardiopulmonary bypass brings relative technical ease to cardiac surgery, tremendously facilitating surgery inside and on the surface of the heart. Unfortunately, in doing so it induces a whole-body inflammatory response that has important clinical implications. In a report from the Society of Thoracic Surgeons National Database, 20% of 22,000 "low-risk" patients developed postoperative complications.115 The incidence of multiorgan dysfunction following CPB was 11%, with a mortality rate of 41% in these patients in another study.116 The deleterious effects of CPB have been termed systemic inflammatory response syndrome (SIRS), post-pump syndrome and post-perfusion syndrome. Systemic inflammatory response syndrome is a complex response resulting from the stimulation of both cellular and humoral natural defense mechanisms and involving several pathways. The triggers include surgical trauma, contact of blood with nonphysiological surfaces in the CPB machine, ischemia and reperfusion injury. Activation of a cascade of physiological mechanisms involving the complement, coagulation, kallikrein, fibrinolytic systems, cellular interactions of leucocytes, platelets and endothelial cells result in the elaboration of mediators such as cytokines, nitric oxide, oxygen free radicals, tumor necrosis factor-
(TNF-), the nuclear factor 
B and cell adhesion molecules.25 The direct physiological insult from the CPB-related systemic inflammatory response has been associated with postoperative multiorgan dysfunction involving cardiac, vascular, pulmonary, neurologic, renal, gastrointestinal and hematologic systems.25,117 Current evidence from RCTs suggests that despite comparable surgical trauma, the OPCAB procedure without CPB and cardioplegic arrest significantly reduces the incidence of SIRS and its associated sequelae (Table 2). This reduced rate of SIRS may contribute to improved organ function and subsequently improved postoperative recovery from surgical revascularization procedures, particularly in critically ill patients.114
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IMPACT ON BLOOD LOSS AND TRANSFUSION REQUIREMENTS
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CPB-induced hemostatic defects may contribute significantly to perioperative morbidity. Potential mechanisms include direct-contact activation of the coagulation and fibrinolytic cascades by the bypass circuit, platelet dysfunction and capillary leakage due to endothelial damage. The inflammatory response may be central to the development of these hemostatic defects. The amount of postoperative blood loss has been correlated with the degree of activation of the complement cascade.117,118 Off-pump coronary artery bypass is associated with a significant reduction in postoperative blood loss, transfusion requirements and transfusion-related cost compared with conventional CABG on CPB (Table 3). This is perhaps secondary to the avoidance of extracorporeal surfaces, the bubble oxygenator, cardiotomy suction, filters, as well as the low level of intraoperative heparinization and markedly reduced systemic inflammatory response in OPCAB patients.119,120
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IMPACT ON RENAL FUNCTION
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Perioperative renal dysfunction occurs in 7%–13% of patients, with 1%–1.5% requiring some form of dialytic therapy. Renal insufficiency following cardiac surgery increases intensive care unit and hospital lengths of stay and greatly increases mortality (27% vs 0.9%).121 The mortality rate in patients requiring postoperative dialysis ranges from 28%–64%.117,121 The incidence of renal dysfunction is directly related to the duration of CPB.122 Ischemia-reperfusion-induced renal injury combined with the inflammatory response to CPB may be important causes of renal dysfunction after CPB.117 Hypoperfusion of the superficial renal cortex has been demonstrated during the rewarming phase of CPB in an animal model. The inflammatory response may exacerbate renal hypoperfusion, both indirectly as a result of hemodynamic instability, and directly via renal arteriolar vasoconstriction and altered intrarenal distribution of perfusion due to changes in catecholamines and nitric oxide concentrations. Tumor necrosis factor- released during CPB induces glomerular fibrin deposition, cellular infiltration, renal cell apoptosis and vasoconstriction, leading to a reduction in glomerular filtration.117,123 According to the current evidence from RCTs (Table 4), OPCAB seems to exert a renal protective action through avoidance of nonpulsatile flow, renal hypoperfusion and hypothermia.
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IMPACT ON MYOCARDIAL FUNCTION
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Major perioperative cardiovascular complications (cardiac death, myocardial infarction, heart failure) occur in at least 10% of CABG patients.117 The Multicenter Study of Perioperative Ischemia Research Group, in a study involving 566 patients after CABG, found that up to 25% fulfilled either electrocardiographic (i.e., presence of Q waves), creatine kinase-MB or autopsy criteria for myocardial infarction; nearly 10% of patients had a Q-wave infarct, while 20.5% fulfilled the creatine kinase-MB criterion of myocardial infarction.124
The inflammatory response may be involved in the pathogenesis of post-CPB cardiovascular dysfunction. Increased hemodynamic instability during cardiac surgery may result from systemic spillover of pro-inflammatory cytokines as well as alterations in nitric oxide homeostasis.125,126 Furthermore, there appears to be a clear link between CPB-induced inflammatory mediators and post-bypass myocardial stunning, ischemia, dysfunction and β-adrenergic desensitization.127 Tumor necrosis factor-, interleukin-1 (IL-1), and IL-6 have been implicated in cardiac myocyte refractoriness to adrenergic stimulation following CPB. Myocardial performance after CPB in elderly patients is suppressed by TNF-, while left ventricular wall motion abnormalities and myocardial ischemic episodes correlate with IL-6 or IL-8 concentrations.127,128 Several RCTs (Table 5) have shown comparable incidences in postoperative myocardial infarction after OPCAB and CABG with CPB, with a more rapid recovery of myocardial oxidative metabolism, better myocardial function, and decreased inotropic requirement following OPCAB. This is secondary to the fact that conventional CABG on CPB with cardioplegic arrest and aortic cross clamping results in global myocardial ischemia, whereas OPCAB leads to local ischemia.62
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IMPACT ON ATRIAL FIBRILLATION
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Atrial fibrillation (AF) occurs in 25%–60% of patients after cardiac surgery.129 The etiology of postoperative AF is multifactorial with the exact pathogenesis of postoperative AF in CABG patients still not understood. However, CPB with cardioplegic arrest has been shown to be the main independent predictor of postoperative AF in patients undergoing coronary revascularization.73 Regional ischemia due to atrial incisions, and acute or chronic myocardial hypoperfusion, contribute to the development of AF by altering atrial conduction and refractoriness. Atrial ischemia may also be the consequence of inadequate cardioplegic protection during CPB.130
Hypomagnesemia, which frequently occurs after CPB, may induce postoperative AF. Administration of magnesium intraoperatively has been demonstrated to decrease the incidence of postoperative arrhythmias.131 Inflammatory events are also suggested to play a role in the pathogenesis of postoperative AF. The development of SIRS with or without clinically proven infection has been shown to be an independent risk factor for new onset of tachyarrhythmias, in particular AF, after cardiac surgery.132 Recently, gene polymorphism modulating IL-6 levels postoperatively has been found to influence the development of postoperative AF, suggesting an inflammatory component and a genetic predisposition to postoperative atrial arrhythmias. Off-pump coronary artery bypass reduces the incidence of postoperative AF compared with CABG on CPB.73,100,102,133–135 This is probably secondary to the blunted systemic inflammatory response, avoidance of atrial cannulation, and reduced myocardial ischemia in OPCAB.
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IMPACT ON NEUROCOGNITIVE DYSFUNCTION
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Neurologic complications increase perioperative morbidity following cardiac surgery, resulting in longer hospitalization, and may increase mortality by up to 10-fold.136 Focal cerebral deficits, such as transient ischemic attacks and stroke, occur in 1%–3% of patients, while less severe clinical abnormalities, such as seizures, are observed in 5%–10%.117 The microembolic phenomenon, a recognized unwanted complication of CPB, has been implicated as a possible source of the neurologic complications associated with CPB.137 Although cannulation and the manipulations required during CPB account for some of the measured cerebral microemboli, the CPB circuit itself has been shown to introduce a significant number of microemboli.138
The inflammatory response also plays a pivotal role in the pathogenesis of post-CPB neurologic injury. The role of endothelial dysfunction and the endothelial-neutrophil interaction in neurologic injury after CPB is well documented. Loss of cerebrovascular endothelial-mediated vasodilation may contribute to the pathogenesis of postoperative perfusion deficits.139 Cerebral microembolization is significantly reduced by avoidance of CPB.74,140 However, the reduction in cerebral microembolization by avoiding CPB has not translated into a significant decrease in the incidence of postoperative stroke and neurocognitive dysfunction. Available evidence from RCTs does not show unequivocal superiority of OPCAB over conventional CABG with respect to the occurrence of stroke and postoperative neurocognitive dysfunction (Table 6), although OPCAB significantly reduces the release of s100 protein and neuron-specific enolase.76–78 The comparable incidence of postoperative stroke after OPCAB may be attributed to aortic manipulation and the use of a tangential (side-biting) clamp that is applied during construction of the proximal anastomoses.141 Adoption of the aortic "no-touch" technique may improve neurologic outcomes after OPCAB.142
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IMPACT ON PULMONARY DYSFUNCTION
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Acute lung injury, defined as the triad of hypoxemia, bilateral pulmonary infiltrates, and normal pulmonary capillary wedge pressure, is a serious and poorly understood complication following cardiac surgery.117 The risk and severity of acute lung injury have been consistently linked to the duration of CPB. Other issues related to CPB, such as the type of oxygenator used, may also contribute to the risk of acute lung injury. Severe lung injury following CPB, while relatively uncommon (1%–3%), has been associated with a 50% mortality.117 Lesser degrees of lung injury, such as reduced oxygenation index, increased ventilation-perfusion mismatch and decreased lung compliance, are seen in up to 12% of patients. Pulmonary injury is detectable even following uncomplicated CPB using sensitive measures of lung injury, such as protein accumulation index and bronchoalveolar lavage neutrophil and myeloperoxidase concentrations.143,144 Early pulmonary dysfunction after cardiac surgery increases morbidity, including renal, neurologic and infectious complications, duration of mechanical ventilation, intensive care unit and hospital stays, and the risk of mortality.143 In theory, avoiding CPB should translate as less postoperative pulmonary dysfunction. However, existing RCTs (Table 7) provide conflicting evidence in this regard. Whereas most RCTs recruiting low-risk patients show a definite reduction in duration of ventilation, with earlier extubation after OPCAB, the effects on respiratory mechanics, oxygenation and work of breathing are similar. On the other hand, the benefits of OPCAB are more pronounced in patients with preexisting pulmonary disease.90,91
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IMPACT ON GASTROINTESTINAL COMPLICATIONS
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Gastrointestinal complications secondary to cardiac surgery are rare (0.4% to 2%) but result in a high mortality rate. This is mainly because such complications are difficult to diagnose and symptoms can be masked in the early postoperative period due to sedation and mechanical ventilation, causing a delay in diagnosis.145 Cardiopulmonary bypass with cardioplegic arrest is the main independent predictor of postoperative gastrointestinal complications in patients undergoing cardiac surgery.146 Gastrointestinal complications are attributed to the period of visceral ischemia, the inflammatory response to CPB and the adverse effects of cardioplegia. Cardiac surgery with CPB is associated with a low-flow state, with subsequent hypoperfusion of end-organs. Perioperative hypotension, hypovolemia, prolonged CPB time, use of vasoconstrictors and postoperative arrhythmias all aggravate end-organ hypoperfusion and could explain the relatively high number of gastrointestinal complications in patients undergoing conventional surgery.146 Off-pump coronary artery bypass significantly reduces the incidence of gastrointestinal complications compared with conventional CABG on CPB, by avoiding prolonged periods of visceral ischemia, the inflammatory response to CPB and the adverse effects of cardioplegia.94
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IMPACT ON MORTALITY AND LENGTH OF HOSPITAL STAY
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The heightened mortality rate documented after on-pump CABG is related to the postoperative organ dysfunction triggered by CPB and the systemic inflammatory response it elicits (post-pump syndrome).147 Avoidance of CPB is associated with significantly lower hospital mortality rates, emphasizing the deleterious effects of CPB on early survival.100,102,105,110 The length of hospital stay after CABG is a function of numerous factors relating to patient demographics (e.g., age and sex), comorbid conditions (e.g., diabetes and chronic obstructive pulmonary disease), severity of coronary heart disease (e.g., New York Heart Association functional class, number of involved coronary arteries, and degree and location of arterial stenoses), and postoperative morbidity (e.g., atrial arrhythmia, prolonged inotropic support, prolonged mechanical ventilatory support, and bleeding).148 Off-pump coronary artery bypass results in a significant reduction in length of hospital stay.100,102,105
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IMPACT ON COST
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The present era of healthcare places a major emphasis on reducing costs while maintaining quality of care and patient satisfaction. The cost of OPCAB surgery has been reported to be approximately 14% to 20% less than on-pump CABG.149 Randomized controlled trials specifically reporting economic outcomes of OPCAB and conventional CABG have shown that OPCAB significantly reduces the total cost for each patient (determined by adding the operation materials, bed occupancy, transfusion and complication management costs) compared with conventional CABG on CPB.52,54,84,95,97
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IMPACT ON QUALITY OF LIFE
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Quality of life has attained more significance in assessing the efficacy of CABG procedure, as figures for CABG-related mortality have reduced considerably in recent times. Quality-of-life instruments cannot directly measure the quality of distal anastomoses. However, measures of quality of life arguably provide important evidence about the relative effectiveness of alternative interventions, i.e., the patient’s view. Randomized controlled trials comparing quality of life after CABG on CPB and OPCAB have shown that the two groups of patients have a similar quality of life, suggesting that OPCAB is equal in efficacy to conventional CABG, if not superior.83,84,96,97
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IMPACT ON GRAFT PATENCY
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The surgical results of OPCAB have demonstrated several advantages of avoiding the potentially detrimental effects of CPB and eliminating intraoperative global myocardial ischemia.150 However, there are concerns about the accuracy and patency of the anastomosis.151 With conventional CABG, the 15-year patency rate is > 97%. This is the gold standard that any new revascularization method must compete against.152 A steep learning curve, distractions caused by cardiac motion or pulmonary insufflation and construction of anastomoses on a moving target have been implicated as factors responsible for inferior graft patency after OPCAB.152 Of the 5 RCTs reporting on graft patency after OPCAB, the 3 largest trials showed no significant differences in patency at varying time points.47,51,84,97,98 The RCT by Widimsky and colleagues98 reported that arterial graft patency after 1 year was 91% in both groups, and there was no significant difference in saphenous graft patency (59% on-pump vs 49% off-pump). Saphenous graft patency per patient was lower in the off-pump group (0.7 vs 1.1 patent anastomoses per patient in the on-pump group; p < 0.01). Of the on-pump patients, 46% had all grafts patent compared to 52% of off-pump patients ( p > 0.05). All grafts anastomosed distally to collateralized chronic total occlusions of native left anterior descending arteries remained patent compared with 23% of grafts on other arteries ( p < 0.0001). The authors attributed poor saphenous graft patency by both techniques to the current spectrum of cardiac surgery candidates: patients with very diffuse disease (and thus poor distal runoff) not amenable to percutaneous intervention.
On the other hand, Khan and colleagues47 reported decreased patency at 3 months in the OPCAB group, thereby reviving debate on the impact of OPCAB on early as well as long-term graft patency. However, closer analysis of the study by Khan and colleagues47 reveals that limited experience of the operating surgeons, consisting of only 98 off-pump procedures, which require a different skill set, during the two years before the study (an average of 25 procedures per surgeon per year) coupled with the relatively low dose of intraoperative heparin, the absence of aggressive antiplatelet therapy with clopidogrel postoperatively, and the failure to use new suction devices to optimize exposure were perhaps some of the confounding factors for poor graft patency in those who underwent off-pump surgery.153
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LEARNING CURVE AS A HINDRANCE TO UNIVERSAL ADOPTION OF OPCAB
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Presently, abundant evidence is available to suggest that excellent results can be achieved when CPB is avoided. Comparison between the costs of both procedures also tilts the balance in favor of OPCAB. From the material costs per patient needed to perform a routine operation to the other economic aspects, such as bed occupancy, postoperative complications and transfusion requirements, OPCAB has been shown to be at least equivalent if not superior to CABG on CPB. Objective analysis through RCTs has also proved that incomplete myocardial revascularization and early anastomotic dysfunction, previously thought to severely compromise this technique, are merely unfounded fears and probably an accompaniment of the learning curve as seen with any new technique.154 Off-pump coronary artery bypass has been accepted as an attractive modality in addition to the traditional on-pump technique. Since its popularization in 1995, many studies have supported the acceptance of OPCAB. Yet, the use of OPCAB is not growing rapidly.155 Although it has not been overwhelmingly shown that off-pump surgery is superior to the conventional on-pump procedure, the technique has its place in our specialty.156 Off-pump coronary revascularization can be accomplished with favorable results in the early postoperative period, and follow-up at 6 to 24 months indicates that OPCAB can be performed safely with a decrease in morbidity and more rapid return to a normal lifestyle.150,157–160 In experienced hands, OPCAB promises improved clinical outcomes by avoiding the morbidity associated with CPB. The surgeon’s challenge with OPCAB and other emerging technologies is to accumulate experience without compromising the safety and beneficial outcome of the procedure.161 Despite a significant learning curve, acceptable outcomes can be achieved throughout the conversion to routine OPCAB by careful patient selection early in a surgeon’s experience. It is recommended that patients with depressed left ventricular function, left main disease and 3-vessel disease be excluded from selection for off-pump surgery early in a surgeon’s experience. Surgeons who have completed training at teaching centers that give considerable exposure to off-pump techniques may be able to incorporate OPCAB into their practice more quickly.161
As surgeon experience with specialized techniques and retractors grows, more complex and higher-risk cases can be performed safely off-pump. Over time, OPCAB can be applied in a broad spectrum of clinical settings, including patients with advanced age, multivessel disease, depressed left ventricular function, or left main disease, and to complete arterial revascularization.161 Intramyocardial coronary arteries, small and calcified targets, and coronary endarterectomy continue to present challenges to the off-pump surgeon; however, these situations have been overcome successfully and do not represent absolute contraindications to OPCAB.161 Currently at institutions with expertise in routine OPCAB, all patients scheduled for isolated coronary bypass are considered candidates for OPCAB, except those with ischemic ventricular arrhythmias, cardiac arrest and patients with a previous left pneumonectomy or deep pectus excavatum, which prevent rightward mobilization of the heart.161
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CONCLUSION
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It was concluded from this analysis that current best-available evidence from RCTs (grade A/level 1) indicates that OPCAB is associated with less systemic inflammation, significant reduction in blood loss and transfusion requirements, preservation of renal function, better myocardial function, reduced incidence of postoperative atrial fibrillation, a comparable incidence of stroke, less postoperative pulmonary dysfunction in patients with preexisting pulmonary disease, reduction in gastrointestinal complications, decreased length of hospital stay, reduced mortality and costs, and comparable quality of life and graft patency. With increasing experience, OPCAB can be safely performed in un-selected patients. In fact, more than patient condition, an individual surgeon’s competence and common sense are probably the most important selection criteria for OPCAB surgery. Hence, the argument that only a select few can benefit from OPCAB no longer holds true. In the last decade or so, OPCAB has been tested through an increasingly rigorous process of scientific validation. From a large number of observational, case-matched, retrospective analyses to randomized controlled trials, there is plenty of evidence that OPCAB surgery is now a proven, safe, cost-effective and reproducible surgical technique.
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ABSTRACT
INTRODUCTION
