Is carotid artery disease responsible for perioperative strokes after coronary artery bypass surgery?
2010; Elsevier BV; Volume: 52; Issue: 6 Linguagem: Inglês
10.1016/j.jvs.2010.09.001
ISSN1097-6809
AutoresYuebing Li, John Castaldo, Jan Van der Heyden, H. W. M. Plokker,
Tópico(s)Intracranial Aneurysms: Treatment and Complications
ResumoThe coronary and extracranial carotid vascular beds are often simultaneously affected by significant atherosclerotic disease, and stroke is one of the potential major complications of coronary artery surgery. As a result, there is no shortage of reports in the vascular surgery literature describing simultaneous coronary and carotid artery revascularizations. Generally, these reports have found this combination of operations safe, but have stopped short of proving that it is necessary. Intuitively, simultaneous carotid endarterectomy and coronary artery bypass surgery could be justified if most perioperative strokes were the result of a significant carotid stenosis, either directly or indirectly. At first glance this appears to be a fairly straightforward issue; however, much of the evidence on both sides of the argument is circumstantial. One significant problem in analyzing outcome by choice of treatment in patients presenting with both coronary and carotid disease is the multiple potential causes of stroke in coronary bypass patients, which include hemorrhage and atheroemboli from aortic atheromas during clamping. But this controversial subject is now open to discussion, and our debaters have been given the challenge to clarify the evidence to justify their claims. The coronary and extracranial carotid vascular beds are often simultaneously affected by significant atherosclerotic disease, and stroke is one of the potential major complications of coronary artery surgery. As a result, there is no shortage of reports in the vascular surgery literature describing simultaneous coronary and carotid artery revascularizations. Generally, these reports have found this combination of operations safe, but have stopped short of proving that it is necessary. Intuitively, simultaneous carotid endarterectomy and coronary artery bypass surgery could be justified if most perioperative strokes were the result of a significant carotid stenosis, either directly or indirectly. At first glance this appears to be a fairly straightforward issue; however, much of the evidence on both sides of the argument is circumstantial. One significant problem in analyzing outcome by choice of treatment in patients presenting with both coronary and carotid disease is the multiple potential causes of stroke in coronary bypass patients, which include hemorrhage and atheroemboli from aortic atheromas during clamping. But this controversial subject is now open to discussion, and our debaters have been given the challenge to clarify the evidence to justify their claims. Yuebing Li, MD, PhD, and John Castaldo, MD, Allentown, Pa Significant carotid stenoses (SCS), defined as ≥50% stenosis in diameter, are associated with an increased risk of postoperative stroke after coronary artery bypass grafting (CABG) surgery.1Schwartz L.B. Bridgman A.H. Kieffer R.W. Wilcox R.A. McCann R.L. Tawil M.P. et al.Asymptomatic carotid artery stenosis and stroke in patients undergoing cardiopulmonary bypass.J Vasc Surg. 1995; 21: 146-153Abstract Full Text Full Text PDF PubMed Scopus (185) Google Scholar, 2Engelman D.T. Cohn L.H. Rizzo R.J. Incidence and predictors of TIA's and strokes following coronary artery bypass grafting: report and collective review.Heart Surg Forum. 1999; 2: 242-245PubMed Google Scholar, 3Naylor A.R. Mehta Z. Rothwell P.M. Bell P.R. Carotid artery disease and stroke during coronary artery bypass: a critical review of the literature.Eur J Vasc Endovasc Surg. 2002; 23: 283-294Abstract Full Text PDF PubMed Scopus (167) Google Scholar Evidence in support of this statement is robust and compelling. The data implicating SCS as the primary cause of the increased stroke risk are neither, even though there seems to be a trend of higher incidence of stroke with more severe carotid stenosis.1Schwartz L.B. Bridgman A.H. Kieffer R.W. Wilcox R.A. McCann R.L. Tawil M.P. et al.Asymptomatic carotid artery stenosis and stroke in patients undergoing cardiopulmonary bypass.J Vasc Surg. 1995; 21: 146-153Abstract Full Text Full Text PDF PubMed Scopus (185) Google Scholar, 3Naylor A.R. Mehta Z. Rothwell P.M. Bell P.R. Carotid artery disease and stroke during coronary artery bypass: a critical review of the literature.Eur J Vasc Endovasc Surg. 2002; 23: 283-294Abstract Full Text PDF PubMed Scopus (167) Google Scholar, 4Salasidis G.C. Latter D.A. Steinmetz O.K. Blair J.F. Graham A.M. Carotid artery duplex scanning in preoperative assessment for coronary artery revascularization: the association between peripheral vascular disease, carotid artery stenosis, and stroke.J Vasc Surg. 1995; 21 (discussion: 161-2): 154-160Abstract Full Text Full Text PDF PubMed Scopus (188) Google Scholar, 5Mickleborough L.L. Walker P.M. Takagi Y. Ohashi M. Ivanov J. Tamariz M. Risk factors for stroke in patients undergoing coronary artery bypass grafting.J Thorac Cardiovasc Surg. 1996; 112: 1250-1258Abstract Full Text Full Text PDF PubMed Scopus (133) Google Scholar In our opinion, the impression of a causal relationship between stroke risk and asymptomatic SCS in cardiac surgery has been largely based on a few false assumptions. To bring these to light, we frame our discussion around these areas to test their validity. The incidence of SCS is high, and most perioperative stroke during CABG occurs in the subgroup of patients with SCS. Data gleaned from preoperative carotid ultrasound imaging would suggest the contrary. The incidence of SCS is fairly low, ranging from 2% to 22%, with an average of 8% to 9% in patients undergoing CABG.3Naylor A.R. Mehta Z. Rothwell P.M. Bell P.R. Carotid artery disease and stroke during coronary artery bypass: a critical review of the literature.Eur J Vasc Endovasc Surg. 2002; 23: 283-294Abstract Full Text PDF PubMed Scopus (167) Google Scholar, 6Lazar H.L. Menzoian J.O. Coronary artery bypass grafting in patients with cerebrovascular disease.Ann Thorac Surg. 1998; 66: 968-974Abstract Full Text Full Text PDF PubMed Scopus (32) Google Scholar Therefore, SCS is not implicated in the mechanism of perioperative stroke in the overwhelming majority of operative patients. Analysis of the status of the carotid arteries in patients with perioperative stroke also bears this out. For example, Wijdicks et al7Wijdicks E.F. Jack C.R. Coronary artery bypass grafting-associated ischemic stroke A clinical and neuroradiological study.J Neuroimaging. 1996; 6: 20-22PubMed Google Scholar reported that among the 13 patients with postoperative stroke who also had carotid evaluation, only 1 patient had an ipsilateral SCS. In one prospective study, 34 of the 38 perioperative strokes (89%) occurred in patients with <80% carotid stenosis.8Bilfinger T.V. Reda H. Giron F. Seifert F.C. Ricotta J.J. Coronary and carotid operations under prospective standardized conditions: incidence and outcome.Ann Thorac Surg. 2000; 69: 1792-1798Abstract Full Text Full Text PDF PubMed Scopus (43) Google Scholar Our recent retrospective analysis indicated that 58 of the 76 perioperative strokes (76%) occurred in patients without SCS.9Li Y. Walicki D. Mathiesen C. Jenny D. Li Q. Isayev Y. et al.Strokes after cardiac surgery and relationship to carotid stenosis.Arch Neurol. 2009; 66: 1091-1096Crossref PubMed Scopus (99) Google Scholar The low incidence of SCS in patients undergoing CABG suggests it is unlikely to be a major contributor to the perioperative stroke risk. The perioperative stroke in patients undergoing CABG occurs primarily in the territory of carotid artery. To the contrary, analysis of the laterality and regional distribution of perioperative strokes on brain imaging indicates that most of these strokes occur in the territory of multiple vessels, the hemisphere contralateral to existing carotid stenosis, or in the distribution of vertebrobasilar arteries. For example, Hise et al10Hise J.H. Nipper M.L. Schnitker J.C. Stroke associated with coronary artery bypass surgery.Am J Neuroradiol. 1991; 12: 811-814PubMed Google Scholar reported that 8 of 15 patients (53%) with evidence of acute infarction on computed tomography scan demonstrated a stroke in the posterior cerebral artery distribution or the cerebellum. Barbut et al11Barbut D. Grassineau D. Lis E. Heier L. Hartman G.S. Isom O.W. Posterior distribution of infarcts in strokes related to cardiac operations.Ann Thorac Surg. 1998; 65: 1656-1659Abstract Full Text Full Text PDF PubMed Scopus (65) Google Scholar examined 19 patients with infarction on computed tomography scan and found 15 patients (79%) and 14 patients (74%) had stroke in the cerebellum and posterior cerebral artery territories, respectively. Wityk et al12Wityk R.J. Goldsborough M.A. Hillis A. Beauchamp N. Barker P.B. Borowicz Jr, L.M. et al.Diffusion- and perfusion-weighted brain magnetic resonance imaging in patients with neurologic complications after cardiac surgery.Arch Neurol. 2001; 58: 571-576Crossref PubMed Scopus (116) Google Scholar used magnetic resonance imaging (MRI) to examine 14 patients, and 9 of 10 patients (90%) with acute lesions on diffusion weighted imaging (DWI) showed multiple strokes in bilateral hemispheres. In one of the most comprehensive reviews to date, Naylor et al3Naylor A.R. Mehta Z. Rothwell P.M. Bell P.R. Carotid artery disease and stroke during coronary artery bypass: a critical review of the literature.Eur J Vasc Endovasc Surg. 2002; 23: 283-294Abstract Full Text PDF PubMed Scopus (167) Google Scholar concluded that primary carotid thromboembolic disease alone is not responsible for up to nearly 60% of strokes based on computed tomography scan or autopsy studies.3Naylor A.R. Mehta Z. Rothwell P.M. Bell P.R. Carotid artery disease and stroke during coronary artery bypass: a critical review of the literature.Eur J Vasc Endovasc Surg. 2002; 23: 283-294Abstract Full Text PDF PubMed Scopus (167) Google Scholar Such a distribution pattern of perioperative stroke also holds true for patients with SCS.9Li Y. Walicki D. Mathiesen C. Jenny D. Li Q. Isayev Y. et al.Strokes after cardiac surgery and relationship to carotid stenosis.Arch Neurol. 2009; 66: 1091-1096Crossref PubMed Scopus (99) Google Scholar, 13D'Agostino R.S. Svensson L.G. Neumann D.J. Balkhy H.H. Williamson W.A. Shahian D.M. Screening carotid ultrasonography and risk factors for stroke in coronary artery surgery patients.Ann Thorac Surg. 1996; 62: 1714-1723Abstract Full Text Full Text PDF PubMed Scopus (184) Google Scholar, 14Dashe J.F. Pessin M.S. Murphy R.E. Payne D.D. Carotid occlusive disease and stroke risk in coronary artery bypass graft surgery.Neurology. 1997; 49: 678-686Crossref PubMed Scopus (67) Google Scholar Therefore, most perioperative strokes occur outside of a single carotid territory. Because <3% of patients undergoing CABG have bilateral SCS,3Naylor A.R. Mehta Z. Rothwell P.M. Bell P.R. Carotid artery disease and stroke during coronary artery bypass: a critical review of the literature.Eur J Vasc Endovasc Surg. 2002; 23: 283-294Abstract Full Text PDF PubMed Scopus (167) Google Scholar neither unilateral nor bilateral carotid stenosis is likely responsible for most of the perioperative strokes based on the infarction territory. Although SCS could be a small contributor to perioperative stroke risk, preoperative carotid revascularization would eliminate stroke in some of these patients and hence should be offered. Data from the North American Symptomatic Carotid Endarterectomy Trial suggested that in patients with SCS, stroke could still be due to small vessel lacunae, thrombotic infarction due to intracranial diseases, or even cardioembolic infarction, but carotid endarterectomy should not help to prevent such strokes.15Inzitari D. Eliasziw M. Gates P. Sharpe B.L. Chan R.K. Meldrum H.E. et al.The causes and risk of stroke in patients with asymptomatic internal-carotid-artery stenosis, in North American Symptomatic Carotid Endarterectomy Trial Collaborators.N Engl J Med. 2000; 342: 1693-1700Crossref PubMed Scopus (548) Google Scholar The incidence of lacunar infarction and intracranial atherosclerosis may not be trivial in patients undergoing cardiac surgery. For example, Libman et al16Libman R.B. Wirkowski E. Neystat M. Barr W. Gelb S. Graver M. Stroke associated with cardiac surgery Determinants, timing, and stroke subtypes.Arch Neurol. 1997; 54: 83-87Crossref PubMed Google Scholar reported that 16% of the postoperative strokes after cardiac surgery can be lacunar syndromes secondary to small vessel disease. Yoon et al17Yoon B.W. Bae H.J. Kang D.W. Lee S.H. Hong K.S. Kim K.B. et al.Intracranial cerebral artery disease as a risk factor for central nervous system complications of coronary artery bypass graft surgery.Stroke. 2001; 32: 94-99Crossref PubMed Scopus (79) Google Scholar reported that 30% of patients undergoing CABG had stenosis in the intracranial arteries. In multivariate analysis, the presence of intracranial disease was also found to have an independent association with the development of perioperative strokes. Furthermore, existing data strongly suggest that most perioperative strokes are cardioembolic, mainly due to the presence of aortic atherosclerosis or atrial fibrillation, or both. Using intraoperative echocardiography, Katz et al18Katz E.S. Tunick P.A. Rusinek H. Ribakove G. Spencer F.C. Kronzon I. Protruding aortic atheromas predict stroke in elderly patients undergoing cardiopulmonary bypass: experience with intraoperative transesophageal echocardiography.J Am Coll Cardiol. 1992; 20: 70-77Abstract Full Text PDF PubMed Scopus (391) Google Scholar identified protruding atheroma in the aortic arch in 23 of 130 patients undergoing cardiac surgery, and perioperative stroke developed in 5 (22%), whereas the stroke risk was only 2% in patients without such atheroma. Gardner et al19Gardner T.J. Horneffer P.J. Manolio T.A. Pearson T.A. Gott V.L. Baumgartner W.A. et al.Stroke following coronary artery bypass grafting: a ten-year study.Ann Thorac Surg. 1985; 40: 574-581Abstract Full Text PDF PubMed Scopus (394) Google Scholar reported that the perioperative stroke risk jumped approximately fourfold higher to 14% in patients with intraoperative evidence of severe aortic atherosclerosis. A multivariable logistic regression analysis of a multicenter database of 19,224 CABG patients suggested that calcified aorta was the single most significant variable associated with perioperative stroke, with an odds ratio of 3.01, whereas the presence of carotid disease was also associated with an odds ratio of 1.59.20John R. Choudhri A.F. Weinberg A.D. Ting W. Rose E.A. Smith C.R. et al.Multicenter review of preoperative risk factors for stroke after coronary artery bypass grafting.Ann Thorac Surg. 2000; 69: 30-35Abstract Full Text Full Text PDF PubMed Scopus (175) Google Scholar In another multivariate analysis, calcified aorta was an independent predictor of perioperative stroke, but SCS was not.8Bilfinger T.V. Reda H. Giron F. Seifert F.C. Ricotta J.J. Coronary and carotid operations under prospective standardized conditions: incidence and outcome.Ann Thorac Surg. 2000; 69: 1792-1798Abstract Full Text Full Text PDF PubMed Scopus (43) Google Scholar Microembolism from the aorta or heart to the brain has been well documented by multiple studies using transcranial Doppler, correlating with the onset and releasing of aorta clamping.21Barbut D. Hinton R.B. Szatrowski T.P. Hartman G.S. Bruefach M. Williams-Russo P. et al.Cerebral emboli detected during bypass surgery are associated with clamp removal.Stroke. 1994; 25: 2398-2402Crossref PubMed Scopus (238) Google Scholar, 22Baker A.J. Naser B. Benaroia M. Mazer C.D. Cerebral microemboli during coronary artery bypass using different cardioplegia techniques.Ann Thorac Surg. 1995; 59: 1187-1191Abstract Full Text PDF PubMed Scopus (56) Google Scholar, 23Clark R.E. Brillman J. Davis D.A. Lovell M.R. Price T.R. Magovern G.J. Microemboli during coronary artery bypass grafting Genesis and effect on outcome.J Thorac Cardiovasc Surg. 1995; 109: 249-257Abstract Full Text Full Text PDF PubMed Scopus (301) Google Scholar Furthermore, D'Agostino et al13D'Agostino R.S. Svensson L.G. Neumann D.J. Balkhy H.H. Williamson W.A. Shahian D.M. Screening carotid ultrasonography and risk factors for stroke in coronary artery surgery patients.Ann Thorac Surg. 1996; 62: 1714-1723Abstract Full Text Full Text PDF PubMed Scopus (184) Google Scholar reported that atrial fibrillation occurred in approximately 30% of postoperative patients, and perioperative stroke occurred in 4.6% of patients with atrial fibrillation compared with 1.5% patients without. Lahtinen et al24Lahtinen J. Biancari F. Salmela E. Mosorin M. Satta J. Rainio P. et al.Postoperative atrial fibrillation is a major cause of stroke after on-pump coronary artery bypass surgery.Ann Thorac Surg. 2004; 77: 1241-1244Abstract Full Text Full Text PDF PubMed Scopus (149) Google Scholar discussed that recurrent atrial fibrillation preceded symptoms of cerebral ischemia in 36.5% of patients with perioperative stroke by a mean of 21.3 hours. In the subgroup of high-risk patients with new postoperative DWI lesions, 75% also had postoperative atrial fibrillation.25McKhann G.M. Grega M.A. Borowicz Jr, L.M. Baumgartner W.A. Selnes O.A. Stroke and encephalopathy after cardiac surgery: an update.Stroke. 2006; 37: 562-571Crossref PubMed Scopus (268) Google Scholar Therefore, in patients undergoing CABG, cardioembolism and probably intracranial arterial stenosis or small vessel disease are the primary mechanisms of stroke. Preoperative cervical carotid revascularization would not prevent these events. SCS reduces distal internal carotid blood flow and hence puts the ipsilateral cerebral hemisphere at risk for ischemia during cardiopulmonary bypass. The carotid plaque at the bifurcation may cause regional hypoperfusion or act as an embolic source in causing a stroke. So far, there are no data to suggest that carotid plaque becomes a more active source of embolism during CABG. Although often asserted as facts, there is very little evidence to suggest that unilateral asymptomatic SCS reduces ipsilateral hemisphere blood flow significantly. Perioperative strokes include both border zone (watershed) and territorial infarctions on brain imaging. Watershed infarctions are now more readily identified on MRI studies.26Floyd T.F. Shah P.N. Price C.C. Harris F. Ratcliffe S.J. Acker M.A. et al.Clinically silent cerebral ischemic events after cardiac surgery: their incidence, regional vascular occurrence, and procedural dependence.Ann Thorac Surg. 2006; 81: 2160-2166Abstract Full Text Full Text PDF PubMed Scopus (109) Google Scholar, 27Gottesman R.F. Sherman P.M. Grega M.A. Yousem D.M. Borowicz Jr, L.M. Selnes O.A. et al.Watershed strokes after cardiac surgery: diagnosis, etiology, and outcome.Stroke. 2006; 37: 2306-2311Crossref PubMed Scopus (138) Google Scholar Although the development of a watershed infarction is frequently attributed to low cerebral flow, this has been challenged repeatedly by autopsy studies. Watershed infarction may occur without SCS or documented intraoperative hypotension.28Graeber M.C. Jordan J.E. Mishra S.K. Nadeau S.E. Watershed infarction on computed tomographic scan An unreliable sign of hemodynamic stroke.Arch Neurol. 1992; 49: 311-313Crossref PubMed Scopus (34) Google Scholar Embolic calcified material or cholesterol crystals were detected in vessels adjacent to the watershed infarction in patients after cardiac surgery.29Gilman S. Cerebral disorders after open-heart operations.N Engl J Med. 1965; 272: 489-498Crossref PubMed Scopus (201) Google Scholar, 30Price D.L. Harris J. Cholesterol emboli in cerebral arteries as a complication of retrograde aortic perfusion during cardiac surgery.Neurology. 1970; 20: 1209-1214Crossref PubMed Google Scholar Watershed infarctions can be caused by microemboli consisting of atheromatous material or tumor masses lodged preferentially in the brain border zone.31Torvik A. Skullerud K. Watershed infarcts in the brain caused by microemboli.Clin Neuropathol. 1982; 1: 99-105PubMed Google Scholar Angiography in three patients with watershed infarction did not show SCS in two patients and revealed an embolic occlusion of the arterial branch corresponding to the site of the infarct in another patient.28Graeber M.C. Jordan J.E. Mishra S.K. Nadeau S.E. Watershed infarction on computed tomographic scan An unreliable sign of hemodynamic stroke.Arch Neurol. 1992; 49: 311-313Crossref PubMed Scopus (34) Google Scholar These brain border zones appear to be favored destinations for microemboli. On the other hand, there is no compelling evidence that cerebral blood flow is significantly reduced distal to SCS in association with cardiopulmonary bypass. Lundar et al32Lundar T. Frøysaker T. Lindegaard K.F. Wiberg J. Lindberg H. Rostad H. et al.Some observations on cerebral perfusion during cardiopulmonary bypass.Ann Thorac Surg. 1985; 39: 318-323Abstract Full Text PDF PubMed Scopus (34) Google Scholar, 33Lundar T. Lindegaard K.F. Frøysaker T. Aaslid R. Wiberg J. Nornes H. Perfusion during nonpulsatile cardiopulmonary bypass.Ann Thorac Surg. 1985; 40: 144-150Abstract Full Text PDF PubMed Scopus (76) Google Scholar described that blood flow in the middle cerebral and internal carotid arteries actually increased rather than decreased during cardiopulmonary bypass as a result of hemodilution. A study that used positron-emission tomography in patients with asymptomatic unilateral SCS found most patients had normal cerebral flow.34Powers W.J. Press G.A. Grubb Jr, R.L. Gado M. Raichle M.E. The effect of hemodynamically significant carotid artery disease on the hemodynamic status of the cerebral circulation.Ann Intern Med. 1987; 106: 27-34Crossref PubMed Google Scholar Hupperts et al35Hupperts R. Wetzelaer W. Heuts-van Raak L. Lodder J. Is haemodynamical compromise a specific cause of border zone brain infarcts following cardiac surgery?.Eur Neurol. 1995; 35: 276-280Crossref PubMed Scopus (16) Google Scholar reported 10 of 37 patients with perioperative strokes had infarction in the vascular border zones. Registered periods of hypotension, lowest mean arterial pressure, and lowest hematocrit were similar among the subgroups of patients with border zone, territorial infarction, or no infarction. Therefore, in patients with unilateral asymptomatic SCS undergoing CABG, the ipsilateral hemispheric blood flow is unlikely to be significantly altered in most patients if significant and prolonged hypotension can be avoided perioperatively. Furthermore, it is arguable whether carotid revascularization would significantly improve cerebral blood flow. Waaijer et al36Waaijer A. van Leeuwen M.S. van Osch M.J. van der Worp B.H. Moll F.L. Lo R.T. et al.Changes in cerebral perfusion after revascularization of symptomatic carotid artery stenosis: CT measurement.Radiology. 2007; 245: 541-548Crossref PubMed Scopus (38) Google Scholar studied cerebral perfusion in 36 patients with SCS and a mean degree of stenosis of 86%. On average, there was merely a 10% increase in cerebral blood flow after carotid stenting or endarterectomy. Preoperative carotid endarterectomy is necessary to avoid carotid territory stroke in patients undergoing CABG. To the contrary, studies suggest that conservative management of SCS can be safe for patients undergoing cardiac surgery. Gerraty et al37Gerraty R.P. Gates P.C. Stroke D.J.C. Carotid stenosis and perioperative stroke risk in symptomatic and asymptomatic patients undergoing vascular or coronary surgery.Stroke. 1993; 24: 1115-1118Crossref PubMed Scopus (99) Google Scholar reported 53 patients with SCS or occlusion (28 patients with ≥80% stenosis or occlusion) underwent vascular or cardiac operations. No ipsilateral perioperative strokes were reported, despite 22 patients experiencing a period of hypotension.37Gerraty R.P. Gates P.C. Stroke D.J.C. Carotid stenosis and perioperative stroke risk in symptomatic and asymptomatic patients undergoing vascular or coronary surgery.Stroke. 1993; 24: 1115-1118Crossref PubMed Scopus (99) Google Scholar Safa et al38Safa T.K. Friedman S. Mehta M. Rahmani O. Scher L. Pogo G. et al.Management of coexisting coronary artery and asymptomatic carotid artery disease: report of a series of patients treated with coronary bypass alone.Eur J Vasc Endovasc Surg. 1999; 17: 249-252Abstract Full Text PDF PubMed Scopus (18) Google Scholar reported that in 94 patients with SCS undergoing cardiac surgery, 71 had unilateral (80%-99%), 17 had bilateral (80%-99%), and 6 patients had unilateral SCS together with a contralateral carotid occlusion. Only one patient developed a perioperative stroke in the hemisphere contralateral to the carotid stenosis. Ghosh et al39Ghosh J. Murray D. Khwaja N. Murphy M.O. Walker M.G. The influence of asymptomatic significant carotid disease on mortality and morbidity in patients undergoing coronary artery bypass surgery.Eur J Vasc Endovasc Surg. 2005; 29: 88-90Abstract Full Text Full Text PDF PubMed Scopus (35) Google Scholar reported 50 patients with asymptomatic SCS (20 with bilateral 80%-99% disease, and 5 with unilateral occlusion and 70%-79% contralateral stenosis) underwent CABG with optimal medical prevention. No strokes occurred ≤30 days of surgery. Baiou et al40Baiou D. Karageorge A. Spyt T. Naylor A.R. Patients undergoing cardiac surgery with asymptomatic unilateral carotid stenoses have a low risk of peri-operative stroke.Eur J Vasc Endovasc Surg. 2009; 38: 556-559Abstract Full Text Full Text PDF PubMed Scopus (40) Google Scholar reported 61 cardiac procedures in patients with unilateral asymptomatic 70% to 99% stenosis (56% of patients also had a contralateral 50%-69% stenosis). No strokes occurred in the 30-day postoperative period. Although larger confirmation studies are still needed, it appears safe and effective in most cases to conservatively manage CABG patients with SCS without the need for preoperative corrective carotid revascularization. There is compelling evidence to conclude that SCS is not the primary cause of most strokes after CABG surgery. This is consistent with the analysis by Stamou et al,41Stamou S.C. Hill P.C. Dangas G. Pfister A.J. Boyce S.W. Dullum M.K. et al.Stroke after coronary artery bypass: incidence, predictors, and clinical outcome.Stroke. 2001; 32: 1508-1513Crossref PubMed Google Scholar who reported that only 6% of the perioperative 333 strokes were secondary to carotid disease, and was borne out in our own single-center retrospective analysis of 4335 patients undergoing cardiac operations. Of the 76 patients with perioperative strokes, 72 (95%) were not related to SCS at the bifurcation.9Li Y. Walicki D. Mathiesen C. Jenny D. Li Q. Isayev Y. et al.Strokes after cardiac surgery and relationship to carotid stenosis.Arch Neurol. 2009; 66: 1091-1096Crossref PubMed Scopus (99) Google Scholar
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