A Comparation of Coronary Artery Bypass Grafting with and without Cardiopulmonary Bypass in Euroscore High Risk Patients

Angiotensin converting enzyme (ACE) and nitric oxide (NO) have been suggested to be inTh e objective of this study is to compare outcomes of coronary artery bypass grafting (CABG) in high-risk patients performed with(ONCAB) and without -(OPCAB) use of cardiopulmonary bypass. From October  till October ,  high-risk patients classifi ed according to European System for Cardiac Operative Risk Evaluation (EuroSCORE) (score ≥) underwent CABG in Cardiovascular Clinic, University Clinical Centre Tuzla, Bosnia and Herzegovina.  patients operated as OPCAB were compared to  patients operated as ONCAB. All data were entered in a patient database (DATACOR) and analyzed in SPSS. OPCAB patients received insignifi cantly less number of grafts than those treated by ONCAB (, vs. ,) (p=,). Stroke was signifi cantly more common in ONCAB group (, vs. ,) (p=,) while the incidence of other postoperative complications and mortality were similar. Th e ventilation time (, vs. , hours) (p=,), retransfusion volume (, vs. , ml) (p=,) and hospital stay (, vs. , days) (p=,) was signifi cantly less in OPCAB group. OPCAB is safe and eff ective in treatment of high-risk patients. Avoidance of cardiopulmonary bypass is associated with reduced incidence of neurologic complications, lower intubation time, retransfusion rate and shorter hospital stay, and in our experience the preferred operative method in such patients.


Introduction
Coronary artery bypass grafting (CABG) became the accepted method of revascularization for coronary artery disease (CAD) in the s.Today, it is one of the most common surgical procedures in USA and Western Europe with more then  - procedures performed per million population ().Results of CABG in general have slowly improved over time in spite of a worsening risk profi le.Most of the procedures are still performed on the arrested heart supported by cardiopulmonary bypass (CPB)-ONCAB, although it has become increasingly common to perform the procedures without use of CPB-OPCAB, using regional myocardial stabilization during grafting.OPCAB has been reported to have superior results especially in certain subgroups of patients (,).Refi nements in technology and clinical experience have resulted in greater acceptance of OPCAB among cardiovascular surgeons (,,).A European System for Cardiac Operative Risk Evaluation (EuroSCORE) value of ≥ represents a high level of risk in patients with coronary artery disease ().In such patients CABG often produced poor results leading to signifi cant morbidity and mortality.Recent trials demonstrated that OPCAB is associated with reduced morbidity and better perioperative results in this group of patients which is related to avoidance of CPB and the infl ammatory response.Th e present study was designed to compare the early and late clinical outcomes of OP-CAB with ONCAB in the treatment of high risk patients.

Materials and Methods
From October  till October ,  high-risk patients classified according to EuroSCORE (score ≥) underwent CABG in Cardiovascular Clinic, University Clinical Centre Tuzla, Bosnia and Herzegovina. patients who underwent OPCAB were compared to  patients operated as ONCAB.Preoperative and postoperative data were reviewed using the computer based patient data program (DATACOR).Selection of operative technique was based on surgeon preference.ONCAB was carried out through median sternotomy.CPB was instituted using ascending aortic cannulation and two stage venous cannulation.Myocardial protection was achieved by intermittent anterograde and/ or retrograde cold blood cardioplegia.After completion of distal anastomoses on the arrested heart, the aortic cross-clamp was removed and the proximal anastomoses performed with partial occlusion of the aorta.OP-CAB was also done through median sternotomy.To achieve adequate exposure of the heart a deep pericardial LIMA stitch () was placed in the oblique sinus of the posterior pericardium.By manipulating this stitch positioning of the heart was safe and eff ective.Th e target vessel was exposed and snared above and/or below the anastomotic site using a - pledgetted Prolene suture and soft rubber tourniquet to avoid injury to the coronary artery ().An intra coronary shunt was frequently used to prevent bleeding during grafting and distal ischaemia ().Visualization of the anastomotic site was improved by a surgical blower.Th e CPB machine was kept in the immediate vicinity with the circuit mounted but without priming.Left anterior descending artery (LAD) was revascularized fi rst prior to major manipulation of the heart.Heparin was given in doses of  mg/kg in ONCAB to keep the activated clotting time (ACT) above  sec.and in OPCAB  mg/kg to keep ACT above  sec.Intraoperative fl ow verification with Transit Time Flow Measurement (TTFM) (Cardiomed Flowmeter, Medistim AS, Oslo, Norway) was used in all grafts as a quality assurance measure.When no reversible cause of poor TTFM results were identifi ed the graft was revised ().In the OPCAB group fl ow measurements were obtained with the proximal snare on and off to assess distal patency.For every graft fl ow curves and waves were standardly recorded.If mean or diastolic fl ow was low, grafts were in general revised according to standard criteria ().

Results
Preoperative patient characteristics are shown in Table .Patients in OPCAB group were significantly older than those in ONCAB group (p=,).There was no significant difference in other preoperative risk factors between the groups.Table  showes postoperative complications and mortality for the two group of patients.The incidence of stroke was significantly higher in the ONCAB group.The incidence of reoperation for bleeding, myocardial infraction (MI), renal disfunction, atrial fibrilation, wound infection, pneumonia and organ failure were comparabile between the groups.-days mortality was higher in ONCAB group (, vs. ,) but with no signifi cant diff erence (p=,).Patients in ONCAB group received insignifi cantly more grafts than those in OPCAB group (, vs. ,; p=,).All patients however had complete revascularisation in the judgement of the surgeon.Intubation time, retransfusion volume and hospital stay were signifi cantly less in OPCAB group (Table ).

Discussion
Results of CABG in general have slowly improved over time in spite of a worsening risk profi le.Data from European and US institutions demonstrated that patients undergoing CABG are progressively older with higher incidence of co-morbidities and it seems that this group will represent a greater proportion of patients undergoing CABG.Optimal management of high-risk patients therefore has become increasingly challenging.OP-CAB has become increasingly common since there is evidence that this technique is less likely to cause major complications.Th e initially use of OPCAB was mainly performed in low risk patients.However as results were analyzed more carefully the main benefi t seemed to occur in higher risk patients ().Complete coro-nary revascularisation through OPCAB was frequently considered impossible in patients with more disease than two vessels.In our study there was no signifi cant diff erence in the average number of grafts (, vs. ,; p=,) demonstrating our ability to revascularize all walls of the heart even in high risk patients.One of the crucial issues in our technique is the initial grafting of the LAD while the heart is minimally displaced.After securing adequate flow to the LAD using intraoperative graft patency verifi cation by TTFM the heart can almost always be manipulated for complete revascularization.Th e main benefi ts of avoiding CPB in high risk patients probably involves avoidance of global ischemia and reduction of a general inflammatory state and minimalization of micro and macro emboli.

Conclusion
Th e results of this study suggests that OPCAB is safe and eff ective in treatment of high-risk patients.Avoidance of cardiopulmonary bypass is associated with reduced incidence of neurologic complications, shortening of respirator time, reduction of retransfusion volume and length of hospital stay.We consider OPCAB the treatment of choice in high risk patients.
EMIR KABIL ET AL.: A COMPARATION OF CORONARY ARTERY BYPASS GRAFTING WITH AND WITHOUT CARDIOPULMONARY BYPASS IN EUROSCORE HIGH RISK PATIENTS EMIR KABIL ET AL.: A COMPARATION OF CORONARY ARTERY BYPASS GRAFTING WITH AND WITHOUT CARDIOPULMONARY BYPASS IN EUROSCORE HIGH RISK PATIENTS