AFRICA CARDIOVASCULAR JOURNAL OF AFRICA Advnce Online Publiction, July 2016 1 Crdiovsculr Topics The effects of the metbolic syndrome on coronry rtery bypss grfting surgery Sevil Özkn, Ftih Özdemir, Oğuz Uğur, Refik Demirtunç, Ahmet Yvuz Blcı, Mehmet Kızıly, Ünsl Vurl, Mehmet Kpln, İbrhim Yekeler Abstrct Bckground: The metbolic syndrome (MS) is clustering of fctors tht re ssocited with incresed crdiovsculr risk. A low-grde inflmmtory process cts s the underlying pthophysiology, which suggests tht the MS my hve detrimentl effect on coronry interventions, including coronry rtery bypss grfting (CABG) surgery performed with crdiopulmonry bypss (CPB). We imed to evlute the effect of the MS on morbidity nd mortlity rtes in the erly postopertive period in ptients undergoing CABG. Methods: We prospectively included 152 ptients (109 mles nd 43 femles; men ge 60.1 ± 8.6 yers) who underwent elective CABG on CPB between Jnury nd September 2011. Erly postopertive morbidity nd mortlity rtes were compred between subjects with nd without the MS. Dignosis of the MS ws bsed on the Americn Ntionl Cholesterol Eduction Progrm Adult Tretment Pnel III (NCEP ATP III) criteri. Results: Of the study group, 64 ptients (42%) hd the MS. The two groups were similr in ge nd gender. In the postopertive period, rtes of tril fibrilltion, wound infection, pulmonry complictions, nd lengths of intubtion, hospitlistion nd intensive cre unit sty were significntly higher in MS ptients (p < 0.01). The MS ws significntly ssocited with wound infection (OR 6.64, 95% CI: 1.72 25.75), pulmonry complictions (OR 6.44, 95% CI: 1.58 26.33), rrhythmi (OR 5.47, 95% CI: 1.50 19.97) nd prolonged intubtion (OR 1.17, 95% CI: 1.05 1.32). The mortlity rte ws 3.1% in the MS group nd 1.1% in the non-ms group, with no significnt difference (p > 0.05). Deprtment of Internl Medicine, Hydrps Numune Trining nd Reserch Hospitl, Istnbul, Turkey Sevil Özkn, MD, sevilfurkn@hotmil.com Refik Demirtunç, MD Deprtment of Crdiovsculr Surgery, Dr Siymi Ersek Trining nd Reserch Hospitl on Thorcic nd Crdiovsculr Surgery, Istnbul, Turkey Ftih Özdemir, MD Oğuz Uğur, MD Ahmet Yvuz Blcı, MD Mehmet Kızıly, MD Ünsl Vurl, MD Mehmet Kpln, MD İbrhim Yekeler, MD Conclusion: The MS ws ssocited with higher rte of erly postopertive morbidity following CABG, without hving significnt effect on the mortlity rte. Keywords: coronry rtery bypss grfting surgery, metbolic syndrome, postopertive morbidity nd mortlity Submitted 30/9/14, ccepted 5/5/16 Crdiovsc J Afr 2016; 27: online publiction DOI: 10.5830/CVJA-2016-056 www.cvj.co.z The metbolic syndrome (MS) is complex metbolic disturbnce chrcterised by insulin resistnce, centrl obesity, hypertriglyceridemi, reduced high-density lipoprotein cholesterol, hypertension nd glucose intolernce. 1 The unifying mechnism responsible for the cluster of crdiovsculr risk fctors in the MS is insulin resistnce, which is lso hllmrk of the MS. 2 It hs been proposed tht insulin resistnce plys mjor unifying role in incresed ischemic events in MS ptients, but this mechnism nd ensuing processes need clrifiction. 3-5 As described by the the Americn Ntionl Cholesterol Eduction Progrm Adult Tretment Pnel III (NCEP ATP III), t lest three of five criteri (Tble 1) hve to be met for MS dignosis. 6 Prevlence of the MS hs been reported s pproximtely 35 40% in industrilised countries. 7 It is n inflmmtory stte chrcterised by incresed levels of dipocytokines such s tumour necrosis fctor-α, interleukin-6 nd C-rective protein, s well s free ftty cids, which cuse vsoconstriction nd endothelil dysfunction. The MS is lso described s low-grde inflmmtory stte mnifested by incresed circulting levels of inflmmtory cytokines. Reduced plsm diponectin nd elevted leptin nd resistin levels hve been observed in MS Tble 1. Metbolic syndrome dignostic criteri (NCEP ATP-III) Metbolic syndrome dignostic criteri 1. Abdominl obesity (wist circumference) Mle > 102 cm Femle > 88 cm 2. Triglycerides > 150 mg/dl (1.7 mmol/l) 3. High-density lipoprotein cholesterol Mle < 40 mg/dl (1.04 mmol/l) Femle < 50 mg/dl (1.3 mmol/l) 4. Blood pressure > 130/85 mmhg 5. Fsting blood glucose > 110 mg/dl (6.11 mmol/l) Americn Ntionl Cholesterol Eduction Progrm Adult Tretment Pnel (NCEP ATP III) dignostic criteri for the metbolic syndrome.
2 CARDIOVASCULAR JOURNAL OF AFRICA Advnce Online Publiction, July 2016 AFRICA ptients. However, unlike leptin nd resistin, which stimulte the immune system, diponectin inhibits the inflmmtory process in the vsculr wll, minly by inhibiting the nucler fctor kpp B pthwy. 2 The pro-inflmmtory stte ssocited with the MS my ply contributory role in excerbtion of the systemic inflmmtory response induced by crdiopulmonry bypss (CPB) nd surgicl trum, nd therefore my predispose ptients to peri-opertive complictions. 8 The MS is cluster of metbolic perturbtions lrgely resulting from bdominl obesity, which is ssocited with incresed risk for type 2 dibetes nd crdiovsculr disese. 9 Although it hs been shown to be predictor of dverse events fter crdiovsculr interventions, nd its ssocition with erly nd lte mortlity nd morbidity following coronry rtery bypss grft (CABG) surgery hs recently been reported, 10 severl studies filed to find such n ssocition. 11-13 We hypothesised tht the MS could dversely ffect the outcome in ptients undergoing CABG surgery nd designed prospective study to determine the impct of the MS on postopertive morbidity nd mortlity rtes fter CABG. Methods We prospectively enrolled 152 consecutive ptients who underwent elective CABG t Siymi Ersek Thorcic nd Crdiovsculr Surgery Centre, Istnbul, Turkey, between Jnury nd September 2011. Dignosis of the MS ws mde ccording to the NCEP ATP III criteri. Ptients were divided into two groups (with nd without the MS) depending on the MS dignosis. Pre-opertive nd opertive dt of ll ptients were prospectively collected nd trnsfered to computerised dtbse. Demogrphic fetures, nd clinicl, lbortory nd intensive cre unit (ICU) dt of the ptients were obtined by trined personnel supervised by nurse uthor, s well s dt on risk fctors, medictions nd functionl sttus. Postopertive complictions were recorded prospectively by n uthor, nd ll mjor dverse events were simultneously vlidted by n experienced crdic surgeon ccording to stndrdised definitions. Ptients undergoing emergency surgery, re-opertive surgery, CABG on beting hert, dditionl vlve repir or replcement, hving n ejection frction of less thn 45%, requiring pre-opertive pcemker implnttion, nd those with liver filure were excluded from the study. The study protocol ws pproved by the institutionl review bord of the hospitl. Demogrphic nd clinicl fetures included ge, gender, men blood pressure, body mss index (BMI), wist circumference, smoking sttus nd co-morbidities, including type 2 dibetes mellitus, systemic hypertension nd obesity. Weight ws mesured in kilogrms using clibrted digitl scle, height ws mesured in centimetres using clibrted stdiometer (Sec GmbH & Co, Germny) nd body mss index (BMI) ws clculted. Wist circumference ws mesured by trined nurse, with cloth tpe round the wist plced in mid-xillry line t the midpoint between the highest point of the ilic crest nd the lowest prt of the costl mrgin. Dibetes mellitus ws defined s the use of dibetes medictions or fsting plsm glucose concentrtion of 110 mg/dl (6.11 mmol/l). The ptients chrcteristics included the following: ge, gender, height, BMI, wist circumference, durtion of dibetes, lcohol consumption, use of insulin or nti-dibetic drugs, low-density lipoprotein (LDL-C) nd high-density lipoprotein cholesterol (HDL-C), triglyceride nd fsting blood glucose levels, smoking sttus, levels of postprndil blood glucose (PPBG), blood ure nitrogen (BUN), cretinine, sprtte minotrnsferse (AST), lnine minotrnsferse (ALT), HbA 1c, hemtocrit, hemoglobin, thyroid stimulting hormone (TSH) nd free T 4, number of grfts used during CABG, left ventriculr ejection frction, nd percentge of crotid rtery stenosis on Doppler ultrsonogrphy. Blood pressure (BP) mesurements were mde pre-opertively using mercury sphygmomnometer with the ptient in sitting position following t lest 10-minute rest. The verge of three mesurements tken t two-minute intervls ws defined s clinicl BP. Hypertension ws defined s BP being 140/90 mmhg from t lest two mesurements or the use of ntihypertensive therpy. A totl cholesterol level of > 200 mg/ dl (5.18 mmol/l) or history of elevted serum totl cholesterol during the pst six months resulting in lipid-lowering drug use ws defined s hyperlipidemi. Current smokers nd former smokers who hd stopped smoking within the pst three yers were considered smokers. Peri-opertive vribles included the number of CABG surgeries, number of grfts, crdiopulmonry bypss time (min) nd ortic cross-clmp time. Postopertive vribles were ll-cuse mortlity, deth within one month fter the opertion, renl filure, postopertive cretinine level > 2.5 mg/dl (221 mmol/l), need for hemodilysis, the use of prolonged pulmonry ventiltor > 24 hours, cute myocrdil infrction, ST-segment chnges, prolonged ventiltion (more thn 72 hours), re-intubtion, wound infection, stroke nd regionl neurologicl dysfunctions tht resolved within 24 hours with no sequel. Additionl dt included the length of ICU nd hospitl sty. Under locl nesthesi, rdil nd pulmonry rteril ctheters were introduced. In ll ptients, nesthesi induction ws obtined before trchel intubtion using midzolm 0.05 0.1 mg/kg, fentnyl 4 8 µg/kg or sufentnil 0.6 0.8 µg/kg, trcurium 0.5 mg/kg or pncuronium 0.1 mg/kg nd thiopentl sodium 1 2 mg/kg. All opertions were performed under CPB t mild to moderte hypothermi (28 32 C). Myocrdil protection ws ensured by intermittent ntegrde or combined ntegrde nd retrogrde sline or blood crdioplegi. Opertive outcomes included the CPB time nd ortic cross-clmp time. Sttisticl nlysis Sttisticl nlysis ws done using the NCSS 2007 softwre (Number Cruncher Sttisticl System, LCC Sttisticl Softwre, Uth, USA). Dt re expressed with descriptive sttistics using men ± stndrd devition, medin, frequency nd percentge. The Kolmogorov Smirnov test ws used to ssess the complince of numericl vribles with norml distribution. The two groups were compred with regrd to pre-opertive demogrphic dt, opertive dt nd erly postopertive morbidity nd mortlity rtes. The Student s t-test ws used for intergroup comprisons of normlly distributed vribles, including ge, BMI, femle nd mle wist circumference, ejection frction, number of grfts, CPB, ortic cross-clmp time, PPBG, BUN, cretinine, totl cholesterol, LDL-C, HDL-C, hemtocrit, hemoglobin, free T 4 nd HbA 1c vlues.
AFRICA CARDIOVASCULAR JOURNAL OF AFRICA Advnce Online Publiction, July 2016 3 Vribles tht did not show norml distrubution (EuroSCORE, fsting blood glucose, AST, ALT, triglycerides, TSH, dringe, ICU sty, hospitl sty, erethrocyte sedimenttion rte nd fresh frozen plsm) were compred using the Mnn Whitney U-test. For the comprison of ctegoricl vribles, Person s chi-squred test ws used when expected nd observed counts were sufficient, Ytes correction for continuity test ws used when observed counts were insufficient (< 20), nd Fisher s exct test ws used when expected counts were insufficient (< 5). A p-vlue < 0.05 ws considered sttisticlly significnt. A post hoc power nlysis showed the dequcy of the smple size for further nlyses. Results There were 109 mles nd 43 femles with men ge of 60.1 ± 8.6 yers (rnge 39 85 yers). According to the NCEP ATP III criteri, 3 64 ptients (42%) hd the MS, while the remining 88 (58%) were free of the MS. The two groups were similr with regrd to ge nd gender. All the MS prmeters (BMI, wist circumference, rtes of hyperlipidemi, hypertension nd dibetes) were significntly higher in the MS group. Pre-opertive demogrphic fetures nd opertive dt for ech study group re shown in Tble 2. When compred with ptients without the MS, those with the MS hd higher levels of fsting glycemi, postprndil glycemi, plsm totl cholesterol, triglycerides nd LDL-C, nd lower HDL-C concentrtion. Lbortory findings of the two ptient groups re shown in Tble 3. Overll, 102 ptients (67.2%) hd dibetes. Medictions of the dibetic ptients included orl nti-dibetic gents (58.8%), insulin (18.6%) or both (10.8%), while 11.8% hd been receiving no dibetes tretment. Tble 2. Comprison of pre-opertive demogrphic nd peri-opertive dt of ptients with nd without the metbolic syndrome MS (+) (n = 64) MS ( ) (n = 88) p-vlue Age (men ± SD) 59.98 ± 6.89 60.55 ± 9.74 0.678 Gender, n (%) Mle 44 (68.8) 65 (73.9) c 0,611 Femle 20 (31.3) 23 (26.1) BMI (kg/m²) (men ± SD) 31.09 ± 5.56 27.58 ± 3.34 Wist circumference (men ± SD) Totl 106.92 ± 10.30 93.69 ± 8.21 Femle 108.86 ± 9.18 95.11 ± 7.77 Mle 102.65 ± 11.54 89.65 ± 8.25 Smoking, n (%) 32 (50.0) 40 (45.5) d 0.579 Alcohol consumption, n (%) 11 (17.2) 15 (17.0) c 1.000 Hyperlipidemi, n (%) 41 (64.1) 31 (35.2) c Hypertension, n (%) 57 (89.1) 11 (12.5) c Crotid Doppler USG (50 nd 70%), n (%) 16 (25.0) 11 (12.5) d 0.076 EF% (men ± SD) 51.25 ± 9.21 52.52 ± 10.67 0.433 EuroSCORE (min mx/medin) 0 9/4 0 11/4 b 0.391 Number of grfts (men ± SD) 3.05 ± 0.93 3.07 ± 0.84 0.883 CPB (min) (men ± SD) 74.09 ± 16.70 71.90 ± 19.82 0.174 Aortic cross-clmp time (min) (men ± SD) 51.08 ± 14.76 47.28 ± 17.84 0.225 Student s t-test; b Mnn Whitney U-Test; c Ytes continuity correction test; d Person s chi-squred test *p < 0.05 **p < 0.01. BMI: body mss index, EF: ejection frction, CPB: crdiopulmonry bypss (presence of the MS ws significntly ssocited with higher prevlence). Tble 3. Comprison of lbortory findings of the ptients with nd without the metbolic syndrome MS (+) (n = 64) MS ( ) (n = 88) p-vlue FBG (mg/dl) (min mx/medin) 79 300/151.00 77 300/110.00 b PPBG (mg/dl) (men ± SD) 191.84 ± 51.09 157.06 ± 53.04 BUN (mg/dl) (men ± SD) 18.25 ± 5.93 17.53 ± 5.66 0.447 Cretinine (mg/dl)(men ± SD) 0.95 ± 0.26 0.96 ± 0.25 0.775 AST (U/l) (min mx/medin) 12 62/25.00 11 51/24.00 b 0.490 ALT (U/l) (min mx/medin) 10 97/28.00 8 61/22.00 b 0.241 Totl cholesterol (mg/dl) (men ± SD) (mmol/l) 226.95 ± 34.18 (2.56 ± 0.89) 185.69 ± 36.08 (4.81 ± 0.93) LDL-C (mg/dl) (men ± SD) (mmol/l) HDL-C (mg/dl) (men ± SD) (mmol/l) Triglycerides (mg/dl) (min mx/ medin) (mmol/l) 134.92 ± 21.80 (3.49 ± 0.56) 36.22 ± 9.21 (0.94 ± 0.24) 71 465/160.00 (0.8 5.25/1.81) 121.89 ± 25.04 (3.16 ± 0.65) 38.77 ± 7.95 (1.00 ± 0.21) 57 482/138.00 (0.64 5.45/1.56) 0.069 b 0.049* Hemtocrit (%) (men ± SD) 39.90 ± 4.35 41.13 ± 4.57 0.098 Hemoglobin (g/dl) (men ± SD) 13.32 ± 1.62 14.01 ± 1.60 0.010* TSH (µiu/ml) (min mx/medin) 0.01 11.34/1.45 0.12 19.00/1.41 b 0.621 Free T 4 (ng/dl) (men ± SD) 1.26 ± 0.22 1.20 ± 0.19 0.071 HbA 1c (%) 7.86 ± 1.59 6.61 ± 1.31 Student s t-test; b Mnn Whitney U-test *p < 0.05 **p < 0.01. FBG: fsting blood glucose, PPBG: postprndil blood glucose, BUN: blood ure nitrogen, ALT: lnine minotrnsferse, AST: sprtte minotrnsferse, LDL-C: low-density lipoprotein cholesterol, HDL-C: high-density lipoprotein cholesterol, TSH: thyroid-stimulting hormone, HbA 1c : hemoglobin A 1c. Postopertive clinicl outcomes re shown in Tble 4. Postopertive mortlity rtes were similr in the two groups, being 3.1% (n = 2) nd 1.1% (n = 1) in ptients with nd without the MS, respectively. However, mnifesttions of postopertive morbidity differed significntly, with higher rtes of tril fibrilltion (AF), wound infection, pulmonry complictions, prolonged intubtion, nd longer durtions of ICU sty nd hospitlistion in ptients with the MS (p < 0.01). The other peri- Tble 4. Comprison of postopertive results of the ptients with nd without the metbolic syndrome MS (+) (n = 64) MS ( ) (n = 88) p-vlue Prolonged intubtion time (h) (min mx/medin) 6 20/11.00 4 28/9.00 b Dringe (ml) (min mx/ medin) 400 2500/650.00 200 1500/ 650.00 b 0.135 Length of ICU sty (h) (min mx/medin) 17 168/24.00 6 96/22.00 b 0.003** Length of hospitl sty (dys) (min mx/medin) 4 35/7.00 1 35/7.00 b RBC replcement (units/ ptient) (min mx/medin) 0 5/2.00 0 5/2.00 b 0.121 FFP replcement (units/ ptient) (min mx/medin) 0 6/2.00 0 12/2.00 b 0.153 Mortlity, n (%) 2 (3.1) 1 (1.1) e 0.573 Myocrdil infrction, n (%) 4 (6.3) 1 (1.1) e 0.162 Surgicl revision, n (%) 5 (7.8) 5 (5.7) e 0.743 Renl filure, n (%) 4 (6.3) 1 (1.1) e 0.162 Wound infection, n (%) 14 (21.9) 3 (3.4) c Pulmonry complictions, n (%) 11 (17.2) 3 (3.4) c 0.009** Stroke, n (%) 4 (6.3) 1 (1.1) e 0.162 Atril fibrilltion, n (%) 13 (20.3) 4 (4.5) c 0.005** b Mnn Whitney U-Test; c Ytes continuity correction test; e Fisher s exct test; *p < 0.05; **p < 0.01. RBC: red blood cells, FFP: fresh frozen plsm.
4 CARDIOVASCULAR JOURNAL OF AFRICA Advnce Online Publiction, July 2016 AFRICA nd postopertive findings (postopertive revisions, incidences of renl impirment, stroke, dringe, need for erythrocytes, fresh frozen plsm replcements, crdiopulmonry bypss time nd ortic cross-clmp time) were similr between the two groups. A sttisticlly significnt reltionship ws found between the MS nd wound infection (OR 6.64, 95% CI: 1.72 25.75), pulmonry complictions (OR 6.44, 95% CI: 1.58 26.33), AF (OR 5.47, 95% CI: 1.50 19.97) nd prolonged intubtion (OR 1.17, 95% CI: 1.05 1.32). In post hoc power nlysis, the observed power for wound infection, pulmonry complictions, AF nd prolonged intubtion time were 0.944, 0.804, 0.843 nd 0.715, respectively. Discussion As MS ptients hve high risk of developing coronry rtery disese, they should be evluted in line with coronry rtery disese guidelines. 10-14,15 The NCEP ATP III stressed the crdiovsculr risk fctors ssocited with the MS. 6 In Turkey, prevlence of the MS is s high s three out of every eight people in the dult popultion. 16 Among coronry rtery disese ptients, its prevlence is 42.7% in mles nd 64.0% in femles, with n overll prevlence of 53.0%. 16 In our study, 42% of the ptients hd the MS, which is similr to other studies in MS ptients undergoing CABG (42, 48, 47%). 11,12,17 Although not sttisticlly significnt, MS ptients lso hd higher smoking rte, which reflected their hbits nd lifestyle. Ptients with nd without the MS did not differ in mortlity rtes; mortlity occurred in two ptients in the MS group (3.1%) nd in one ptient in the non-ms group (1.1%). Other studies reported similr mortlity rtes in the two ptient groups. 11,12,17 Swrt et l. 11 compred 370 ptients with the MS (s defined by the Interntionl Dibetes Federtion nd NCEP ATP III criteri) nd 503 ptients without the MS in terms of mortlity nd morbidity rtes following CABG. The two groups hd similr ge distribution nd hd mortlity rtes of 1.9 nd 1.6%, respectively (p = 0.7348). The verge EuroSCORE differed significntly between the two groups, being 3.26 (medin 3) in the MS group nd 3.61 (medin 3) in the non-ms group (p = 0.0494). The rtes of re-explortion, stroke, renl insufficiency, prolonged mechnicl ventiltion, nd the need for rewiring of sternl dehiscence were similr in the two groups. The mount of medistinl dringe ws lso similr (624 vs 670 ml). The need for homologous blood trnsfusion ws less (p = 0.0012), but hospitl sty ws longer (p < 0.00001) in the MS group. The uthors concluded tht MS did not hve ny detrimentl clinicl effects on either pre-opertive risk fctors or outcomes fter CABG. Özyzıcıoğlu et l. 12 exmined the effects of the MS on postopertive mortlity nd morbidity rtes in ptients undergoing CABG. Compred with ptients without the MS, those with the MS (NCEP ATP III criteri) hd higher incidence of wound infection (p < 0.05), but similr rtes of tril fibrilltion, revision surgery due to hemorrhge, ventriculr tchycrdi, ventriculr fibrilltion, prolonged intubtion nd mortlity rtes. These discrepncies my hve resulted from differences in the definition of postopertive morbidity nd postopertive serious events, nd in the durtion of follow-up periods. Criteri used to define the MS my lso led to discrepnt results, nmely, cut-off points of criteri for the MS in vrious popultions or even prmeters of the MS (wist circumference insted of BMI) my vry. These differences my hve confounding effect on ssessing the ssocition between pre-opertive MS nd postopertive complictions. 11,12 Inhibition of dipocytes is incresed in obese people, long with mny proteins with immunomodultory ctivity. Thromboembolic events re more commonly seen in MS ptients undergoing CABG becuse prothrombotic stte frequently occurs postopertively. 2 Yılmz et l. 18 suggested tht the MS might serve s predictor of postopertive occlusion of sphenous vein grfts fter CABG. In our study, the incidences of peri-opertive myocrdil infrction were similr between ptients with nd without the MS. It is likely tht peri-opertive myocrdil infrction is not determined by erly grft occlusion, but rther by fctors relted to myocrdil protection strtegies or unknown fctors, which could explin the bsence of significnt difference between ptients with nd without the MS. In the present study, lengths of hospitlistion nd ICU sty were significntly longer in the MS group. Brckbill et l. 13 showed tht femle ptients with the MS undergoing CABG surgery were t incresed risk for longer postopertive sty s well s for in-hospitl deth. Brdkcı et l. 19 reported tht, compred with the ptients without the MS, those with the MS hd significntly higher femle-to-mle rtio, nd significntly higher rtes of fmily history of ischemic hert disese, nd coronry rtery occlusions involving the nterior descending coronry, circumflex nd right coronry rteries. This difference could be noteworthy not only for incresed morbidity rtes, but lso for tretment costs. Similr to previous studies, 11,12,17,20 no significnt difference ws found in the occurrences of stroke nd renl impirment fter CABG between the MS nd non-ms groups (p > 0.05). However, mny prmeters of morbidity, including AF, wound infection, pulmonry complictions, prolonged intubtion, nd lengths of ICU nd hospitl sty were significntly higher in ptients with the MS (p < 0.01). Ardeshiri et l. 20 found tht the MS represented n incresed risk for telectsis nd tht ptients with the MS hd longer ICU sty following CABG. Özyzıcıoğlu et l. 12 concluded tht wound infection ws significntly more frequent in coronry rtery disese ptients with the MS thn in those without the MS (p < 0.05). In multivrite nlysis, the odds rtios of postopertive stroke nd renl filure in MS ptients were found to be 2.47 nd 3.81, respectively. 17 The high prevlence of postopertive events in MS ptients my be ssocited with BMI nd n incresed incidence of dibetes. 21 Brdkçı et l. 19 found significntly prolonged intubtion times, ICU nd hospitl sty, nd significntly higher rte of pulmonry complictions in MS ptients; however, in contrst with our study, they reported significnt increses in the rtes of mortlity nd peri-opertive myocrdil infrction. Moulton et l. 22 reported tht obesity ws not risk fctor for dverse events fter crdic surgery, except for the incresed number of superficil surgicl wound infections nd higher incidence of tril rrhythmis. Kopelmn et l. 23 concluded tht thorcic nd bdominl dipose tissue might be cuse of ventiltion nd perfusion mismtch, which could induce decline in respirtory function by creting resistnce to brething exercises. In our study, pulmonry complictions were significntly higher mong ptients with the MS (p < 0.01). This my be explined by negtive effect of the MS on postopertive
AFRICA CARDIOVASCULAR JOURNAL OF AFRICA Advnce Online Publiction, July 2016 5 respirtory function, leding to incresed postopertive pulmonry complictions. Concerning the reltionship between pulmonry function nd the MS, it ws shown tht mle dults with the MS hd decresed vitl cpcity. 24 Bgheri et l. 25 indicted tht BMI ws not predictor of mortlity fter CABG, but pulmonry complictions were independent predictors of mortlity in the postopertive period. Crdiopulmonry bypss procedures re relted to inflmmtory response nd free rdicl ccumultion. 8 It is known tht MS ptients hve n ongoing, low-grde inflmmtory process, which cn be excerbted during surgery. They lso hve incresed systemic oxidtive stress cused by oxidtive trnsformtion of LDL-C. 26 The role of lipolytic ctivity by bdominl ft storge hs been emphsised in the production of free ftty cids. 26 These free ftty cids exert significnt pro-rrhythmic effect in ischemic events. This effect hs been documented for ventriculr rrhythmogenicity, but it hs yet to be demonstrted in the genertion of AF. Therefore, further reserch is needed to clrify whether, like other fctors, free ftty cid burden ssocited with hyperlipolytic viscerl ft storge contributes to the genertion of postopertive AF. 27 It is believed tht MS ptients re more prone to postopertive AF through potentil pthwy. 28 Atril remodelling involves two substrtes: tril rchitecture cting s n ntomicl substrte (involved in tril dilttion, fibrosis), nd electricl inhomogeneity cting s functionl substrte (involved in shortness of effective refrctory period, dispersion of refrctoriness nd conduction, bnorml utomticity, nd nisotropic conduction). 29 These ltter processes hve been shown to be potentil substrtes for postopertive AF. 30 Bell nd O Keefe reported tht postopertive AF ws observed in 25% of ptients undergoing CABG, nd ws ssocited with elevted rtes of mortlity nd postopertive stroke, prolonged hospitl sty nd incresed cost of hospitlistion. 31 Kr et l. 32 found tht the incidence of AF ws high (19.2%) fter CABG, nd they defined some independent clinicl predictors. Echhidi et l. 2 reported tht the MS hd significnt effect on clinicl outcomes fter crdic surgery nd ws n independent predictor of postopertive AF. Girerd et l. 33 showed significnt correltion between postopertive AF nd incresed wist circumference nd/or incresed C-rective protein levels. The uthors lso reported tht the MS ws n independent risk fctor for AF occurring fter CABG. 32 In our study, the rte of AF ws significntly higher (20.9%) in MS ptients compred to those without the MS (p < 0.01). Ghripour et l. 34 found no significnt difference in the incidence of postopertive stroke between CABG ptients with nd without the MS. In our study, lthough the rte of stroke ws higher in MS ptients (6.3 vs 1.1%), it ws not ssocited with significnt difference (p = 0.162). This my be ttributed to the bsence of therosclerotic plque in the crotid rteries. In our ptients, crotid Doppler ultrsound showed moderte stenosis (50 70%), which ws considered insufficient to led to hemodynmiclly significnt conditions. Crotid stenosis is n importnt risk fctor for stroke during CABG surgery, but neurologicl events my develop from other cuses s well, including ortic nd crotid therosclerosis (62%), intrcrdic thrombi (1%), hemorrhge (1%), hypoperfusion (11%), nd other fctors of unknown origin (25%). 35 The severity of crotid stenoses detected in ptients undergoing CABG hs been reported s greter thn 70% in 10% of the cses, 50 70% in 9 22% of the cses, nd less thn 50% in 80 91% of cses. 35,36 Of interest, 50 75% of ptients who suffered stroke did not hve crotid stenosis. 37 Lee et l. 38 reported tht intrcrnil therosclerosis ws the min determinnt of stroke, while extrcrnil therosclerotic processes plyed reltively smller role. Of note, pre-opertive criticl risk fctors for mortlity fter CABG were not ffected by the MS. By contrst, ptients without the MS required urgent opertions more frequently thn did those with the MS. This is not surprising becuse ptients with the MS re normlly on strict follow up to control hypertension, dibetes mellitus nd dyslipidemi, ll of which re known to be underlying risk fctors for coronry rtery disese. Therefore, ptients without the MS nd with poorly controlled coronry risk fctors re more likely to hve urgent, non-elective interventions. The presence of fctors known to increse mortlity rtes in MS ptients my itself be limittion to the study. These fctors include mle gender, widespred coronry rtery involvement, nd incresed cross-clmping time. Therefore, the effect of the MS on mortlity rte itself my be considered limittion. The biggest limittion ws tht the study ws underpowered to drw conclusions on some of the outcomes, for exmple, mortlity. Components of the MS cnnot be completely minimised by conventionl phrmcologicl tretment modlities. It is well known tht sttins, ngiotensin converting enzyme inhibitors, nd bet-blockers hve little or no effect in metbolic disturbnces observed in MS cses. 28 Conclusion Since MS ptients lredy present with mny crdiovsculr risk fctors, the MS ws ssocited with incresed morbidity rtes in the erly postopertive period fter CABG; however, its effect on erly mortlity rte ws similr to tht seen in ptients without the MS. Considering the incresed postopertive morbidity rte, the MS should be tken into considertion in pre-opertive ssessment of CABG ptients. References 1. Alberti KG, Eckel RH, Grundy SM, Zimmet PZ, Cleemn JI, Donto KA, et l. Hrmonizing the metbolic syndrome: joint in terim sttement of the Interntionl Dibetes Federtion Tsk Force on Epidemiology nd Prevention; Ntionl Hert, Lung, nd Blood Institute; Americn Hert Assocition; World Hert Federtion; Interntionl Atherosclerosis Society; nd Interntionl Assocition for the Study of Obesity. Circultion 2009; 120(16): 1640 1645. 2. 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