Objective: There is no common concencus the clinical results of coronary artery bypass grafting (CABG) surgery patients who underwent off-pump or conventional techniques. Our aim of this study was to compare the changes of myocardial functions, patients’ clinical results, biochemical marker release during surgery and postoperatively in On- and Off-Pump CABG surgery. Method: A consecutive series of 50 coronary artery disease (CAD) patients who underwent elective CABG surgery included for this study. The patients were divided into two groups (Group 1, N = 25 and group 2, N = 25). Demographic data including the patients’ age, gender, body mass index (BMI), diseased coronary artery numbers, LVEF were similar. Postoperative red package blood cell, fresh frozen plasma, and thrombocyte requirements were high in On-Pump group ( p < 0.05). But there was not any significant difference when compared the number of unexpected surgery because of mediastinal bleeding after operations in both groups. Preoperative and postoperative N-Terminal Pro-Brain Natriuretic Peptide (NT-proBNP), cardiac Troponin-I (cTnI) levels during and after surgery, and left ventricular ejection fractions (LVEF) prior to discharge from hospital were compared. Results: There were no statistical significancy when compared postoperative mortality and morbidity. The operations time was low in off-pump group ( p < 0.05). The NT-proBNP levels were similar in both groups ( p > 0.05). However, cTnI levels were significantly higher in the on-pump group ( p = 0.0001). Postoperative LVEF decreased significantly in both groups when compared to preoperative echocardiography examinations ( p = 0.001). But the changes of postoperative LVEFs in both groups were not statistical significant ( p > 0.05). Conclusion: Our study results indicated that cardiac enzyme release was high after On-Pump CABG surgery. However, LVEF decreased in both techniques. There were some advantages of OPCAB operations such as decrease of inflammatory responses and angina pectoris incidence due to extracorporeal circulation; however, these techniques did not affect postoperative mortality and morbidity. Therefore, in selected cases to provide longer operation time, Off-Pump CABG could be used but it has no superiority over On-Pump CABG surgery.
The development of the cardiopulmonary bypass pump (CPB) was a milestone in the development of cardiac surgery. However, recent studies have reported several triggered inflammatory reactions as a response to the mechano-physiological aspects of CPB. These inflammatory reactions can have both systemic and local cardiac-adverse effects [
Myocardial enzymes release and postoperative LVEF were investigated in a number studies in On- or Off- Pump CABG techniques [
This study was conducted between January and December 2014 in Dıskapı Yıldırım Beyazıt Training and Research Hospital, in Ankara, Turkey. The study was approved by the Local Ethical Committee for Medical Research of our hospital. All study protocols were designed according to the guidelines of the Helsinki Declaration. Informed consent was obtained from all patients.
A consecutive series of 50 patients who had undergone elective CABG surgery were included in this prospective research. Patients with poor left ventricle (LVEF < 35%), renal failure and concomitant heart valve disease which required repair or replacement, chronic liver disease and Re-Do operation were excluded from the study.
The patients were randomly divided into two groups.25 patients operated under CPB (Off-Pump Group 1 (OPCAB), N = 25). The mean number of grafted coronary artery was 3.1 ± 0.9 and 3.4 ± 1.1 in Group 1 and 2, respectively. When we compared patients data there were no any statistical significance. The mean age of the patients was 58 ± 11.4 y and 62 ± 9.6 y in group 1 and 2, respectively. 17 patients in group 1 and 15 patients in group 2 were male. In addition, there were no statistical significance when compared to number of anastomosis, except operation time. In all patients, left internal thoracic artery was used to vascularised left anterior descending artery. For other diseased coronary arteries saphenous veins were used. Sequential bypass grafting technique was used in 8 patients from group 1 and in 7 patients in group 2. All patients have multyvessel coronary artery or left main coronary disease. In On-Pump and Off-Pump group, coronary artery stenting was performed in seven and nine patients, respectively. In 5 patients from On-Pump and 6 patients from OPCAB have left main coronary artery disease.
BMI and systemic disease such as hypertension, and diabetes were noted in both groups. There was no any statistical significance (p = 0.67). We compared total operation time, intraaorticballon pump (IABP) use, inotropic support requirement, intubation and ICU staying time in both groups by blinded ICU personels.
Surgical Techniques in On-Pump GroupsMedian sternotomy was performed. Aortic and single venous cannulation was performed. CPB was instituted after the cannulation. The myocardial protection was performed has been provided using antegrade and retrograde cold blood cardioplegia after aortic cross-clamping. For LAD artery the left internal thoracic artery (ITA) has been harvested. For the remaining diseased vessels, saphenous vein was used. After distal anastomosis, cross-clamp was released and the heart is beating. If needed inotropic agent was administered prior to weaning from extracorporeal circulation. Proxymal venous anastomoses has been done using a side clamp. The cross- clamp time and CPB time have been noted by the anaesthesiologist.
After midline sternotomy, the left ITA and saphenous vein have been prepared for revascularisation. The heart is elevated using a spunch. After coronary arteriotomy, intracoronary shunt was inserted to provide blood supply and myocardial ischemia during the anastomosis. The octopus was used in all operations. Firstly, the left ITA was anastomosed to the LAD artery. After then, venous grafts have been anastomosed to diseased coronary arteries. If needed, inotropic agent was administered. After the completion of anastomosis proximal venous anastomosis were performed using an aortic side clamp.
To measure cardiac trophonin and Pro-BNP blood levels samples were given from venous line (Before the induction of anaesthesia, at 2 h, 4 h, 8 h and 24 h. In OPCAB group, the samples collection has been given immediately after distal anastomosis. In On-Pump group, the first cardiac enzyme level has been given immediately after aortic cross-clamping. After then, the samples have been obtained at the second h, at 4 h, 8 hy and at the and of 24. Plasma NT-proBNP has been calculated according to cTnI levels measurements.
Each sample was placed into a gel containing biochemistry tubes for serum separation and centrifuged at 4˚C for 10 minutes at 3500 rpm. After centrifuge, the obtained serums were placed into small Eppendorf Tubes®. Serum c-TnI levels were measured using direct automated Chemiluminescence System (ACS-180, Chicron Diagnostics, East Walpole, MA, USA) as ng/ml.
After blood sampling, each sample was placed into EDTA-containing tubes and centrifuged at 4˚C for 10 minutes at 3.500 rpm. After centrifuge, obtained serums were placed into small Eppendorf Tubes®. All samples were stored −80 until evaluation of the steps began for NT-proBNP. Serum NT-proBNP concentration was measured using a sandwich enzyme immunoassay NT-proBNP ELISA kit (Roche Diagnostic, Meylan, France; range 5 - 35,000 pg∙ml−1) as pg/ml.
Data were analysed using SPSS software, version 17.0 (SPSS, Chicago, IL). Continuous variables were expressed as mean + standard deviation. The distribution of continuous variables was evaluated using the Kolmogorov-Smirnov test. Independent groups with normal distribution were compared with independent sample t-tests. The Mann-Whitney U test was used to determine the difference of variables in groups with non-normal distributions. Nominal data were compared with chi-square tests. The meanings of increments in the repeated measurements were evaluated with “General Linear Model-Repeated Measures”, and p < 0.05 was considered statistically significant.
There was no mortality after surgery in both groups. The mean BMI was 26.70 ± 3.39 kg/m2 and 27.88 ± 5.04 kg/m2 in OPCAB and on-pump groups, respectively (p < 0.05). Likewise, hypertension in 9 (36%) vs 6 (24%) patients in on-pump and off-pump group, respectively. Preoperative LVEF was 56.24% ± 12.1% and 58.24% ± 14.6% in group 1 and 2, respectively. These were similar in both groups (p < 0.05). Preoperative serum NT- proBNP concentrations were 400.05 ± 295.68 pg∙ml−1 and 388.93 ± 459.88 pg∙ml−1 in the on-pump and off- pump groups, respectively (p < 0.05). This was statistically significant. Preoperative and postoperative c-TnI values were 0.15 ± 0.27 ng/ml and 0.69 ± 011 ng/ml in on-pump group (p = 0.023). These values were 0.08 ± 0.17 ng/ml and 0.31 ± 0.9 ng/ml in OPCAB group. This was no statistically significant (p > 0.05).
Intubation time was detected as 340.16 ± 51.73 h in OPCAB group. This was similar when compared to on- pump group (300.60 ± 64.68 h) (p = 0.021; t = 2.388). The mean cardiopulmonary bypass time was 120.16 ± 30 h, and the mean cross-clamp time was 69.36 ± 20.64 h in on-pump group. The mean hospital staying time was 8.68 ± 4.10 d and 7.36 ± 3.89 d in off-pump and on-pump CABG group, respectively. In on-pump CABG the short hospital staying time was detected (p = 0.039, Z = −2.060). One patient required inotropic support in the off- pump group, while 13 (52%) patients needed inotropic support in the on-pump group (p < 0.001, χ2= 14.286).
The mean preoperative LVEFs were 59% ± 14.5% and 61% ± 7.6% in OPCAB and on-pump group, respectively (p = 0.86). The mean postoperative LVEF was calculated as 46.2% ± 7.4% in OPCAB (p = 0.024). This value was calculated as 53.4% ± 10.6% in on-pump group (p = 0.021). Intragroup analyses showed that both CABG techniques reduced LVEF after operation. Intergroup analyses demonstrated that the change of LVEF was similar.
Inon-pump and OPCAB group, preoperative mean NT-proBNP concentrations were326.50 ± 250.20 pg/ml and 347.94 ± 284.20 pg/ml, respectively. In On-Pump patients, these values were 390.32 ± 371.81 pg∙ml−1, and 607.17 ± 485.13 pg∙ml−1 at 2 h, 4 h, 8 h and 24 h, respectively. In OPCAB group, serum NT-proBNP concentrations were 327.26 ± 383.72 pg/ml, 335.36 ± 362.61 pg ml-1, 456.97 ± 502.60 pg∙ml−1, 541.92 ± 459.25 pg∙ml−1 at 2, 4, 8 and 24 hours, respectively. Comparisons of Serum NT-proBNP concentrations of all sampling times were statistically insignificant between groups (p < 0.05). The distribution curves of NT-proBNP levels in the two groups are presented in Graph 1.
Cardiac Tn-I values was calculated as 4.59 ± 4.25 and 0.43 ± 0.29 ng/ml in on-Pump and OPCAB group (p < 0.001, Z = −5.734). c-Tn release was calculated at 4. h 5.78 ± 5.61 vs. 0.49 ± 0.27 ng/ml in on-pump and OPCAB group (p < 0.001, Z = −5.890). At 8 h, this value was measured as 6.58 ± 7.97 in on-pump and 0.65 ± 0.34 ng/ml in OPCAB (p < 0.001, Z = −5.908). At the end of 24 h, troponin-I levels were measured as 5.39 ± 7.72 in on-pump, and 0.69 ± 0.75 ng/ml in OPCAB (p < 0.001, Z = −4.680). These measurements were significantly different when compared to both groups. The curves of cardiac troponin-I levels in both groups are summarized in Graph 2. A comparison of preoperative and postoperative (2, 4, 8, and 24 h) NT-proBNP concentrations and cTnI values in two groups are summarized in
Graph 1. The distribution of NT-proBNP levels in groups.
Graph 2. The distribution of cTnI levels in groups.
On-pump NT-proBNP pg∙ml−1 | Off-pump NT-proBNP pg∙ml−1 | Mann-Whitney U Test | On-pump cTnI ng/ml | Off-pump cTnI ng/ml | Mann-Whitney U Test | |||
---|---|---|---|---|---|---|---|---|
*p | Z | *p | Z | |||||
Preoperative | 400.05 ± 295.68 | 388.93 ± 459.88 | 0.290 | −1.057 | 0.15 ± 0.27 | 0.290 | 0.174 | −1.358 |
2nd hour | 326.50 ± 250.20 | 327.26 ± 383.72 | 0.273 | −1.096 | 4.59 ± 4.25 | 0.273 | 0.000 | −5.734 |
4th hour | 347.94 ± 284.20 | 335.36 ± 362.61 | 0.352 | −0.931 | 5.78 ± 5.61 | 0.352 | 0.000 | −5.890 |
8th hour | 390.32 ± 371.81 | 456.97 ± 502.60 | 0.839 | −0.204 | 6.58 ± 7.97 | 0.839 | 0.000 | −5.908 |
24th hour | 607.17 ± 485.13 | 541.92 ± 459.25 | 0.614 | −0.504 | 5.39 ± 7.72 | 0.614 | 0.000 | −4.680 |
*p < 0.05 is significant.
Significant differences were found in regard to post operative c-Tn-I values and inotropic support requirement between On- and Off-Pump techniques. But, in contrast to some previous researches [
At the beginning of the 1980s, Bufallo et al. [
Off-pump CABG confered similar overall mid-term survival when compared with On-Pump. On-pump CABG was associated with a significant trend towards a long-term survival advantage; however, this was no longer present when subgroup analysis of only randomized controlled trials, and propensity-matched studies was performed. There was an increase in angina recurrence after Off-Pump technique but no difference was seen in previous studies. No significant differences were observed when compared secondary outcomes of both techniques. Previous analysis demonstrated comparable mid-term mortality and mid- to long-term morbidity between OPCAB and On-Pump. On-pump CABG might be associated with improved long-term survival. However, analysis of only randomized controlled trials and propensity-matched studies demonstrated comparable long-term mortality between OPCAB and On-Pump.
The most frequently discussed topics are quality of anastomosis and long-term graft patency rates for the off- pump technique. Imamaki et al. reported equivalent anastomosis qualities between on-pump and off-pump techniques [
It was reported that serum NT-proBNP levels were associated with myocardial ischemia and improved ventricular functions after open heart surgery [
Cardiac Troponin I (cTnI) was defined as a marker of myocardial injury, which has reported to be superior insensitivity and specificity when compared with habitual biomarkers, such as creatine kinase and myoglobin [
Our study results demonstrated that cardiac enzyme was low after Off-Pump CABG surgery. However, LVEF decreased in both techniques in the postoperative period. Benefits of OPCAB operations such as inflammatory response during surgery have been demonstrated previously. According to previous clinical researches, our results showed that off-pump technique could not affect postoperative mortality and morbidity in CABG operations. In our opinion, Off-Pump CABG can be used in selected CAD patients but it has no superiority over On- Pump CABG. Higher postoperative cTnI levels were measured in patients operated on with the on-pump procedure; however, LVEF levels were similar compared to two groups. We need comprehensive studies for comparing on-pump and off-pump procedures in terms of short and long-term left ventricular functions and cardiac NT-Pro-BNP values.
Z. Temizturk,D. Azboy,K. Karapınar,I. Ince,M. Bozguney,S. Sahinalp,O. Ersoy,A. Bulut,E. Yucel, (2015) The Comparison of Clinical and Biochemical Outcomes in Off-Pump and Conventional Coronary Artery Bypass Grafting Surgery. Open Access Library Journal,02,1-8. doi: 10.4236/oalib.1101799