THE CHOICE OF ON-OR OFF-PUMP CORONARY BYPASS GRAFTING – A SURGEON ’ S DILEMMA

Background: Off -pump coronary bypass grafting (OPCAB) is a routine method of heart revascularization. This study was designed to compare the results of OPCAB and ONCAB performed by a single surgeon at our institution over a 3-year period. Methods: The study enrolled 345 patients undergoing elective myocardial revascularization procedures, of which 173 (50.1%) were OPCAB and 172 (49.9 %) were ONCAB. The postoperative outcomes of both groups were analyzed, retrospectively. Results: The mean number of grafts was signifi cantly lower in the OPCAB group (2.9) than in the ONCAB group (3.7). There were no postoperative myocardial infarctions or hospital deaths in any of the patients. The postoperative total blood loss was signifi cantly higher in the ONCAB group. The frequencies of postoperative confused states, strokes, postoperative transfusions, reoperations for bleeding, and atrial fi brillation, and the durations of intubation, ICU stay, and hospital stay did not diff er signifi cantly between the two groups. Conclusions: The OPCAB procedures are safe and provide good clinical outcomes, similar to those of ONCAB operations. The outcomes of this study favor neither of the compared techniques.


INTRODUCTION
Off -pump coronary bypass grafting (OPCAB) is a routine method for heart revascularization, but its superiority over conventional on-pump coronary bypass grafting (ONCAB) has not been clarifi ed 1 .One of the most important factors is whether OPCAB is safe and more eff ective than ONCAB in the hands of a particular surgeon.
This retrospective observational study was undertaken to compare the results of OPCAB and ONCAB performed by a single surgeon at our institution over a 3-year period.

METHODS
A total of 345 consecutive elective, primary, isolated heart revascularizations were performed between January 2004 and January 2007 by a single surgeon with experience in both ONCAB and OPCAB in our department.The preoperative characteristics of both groups are listed in Table 1.
The ONCAB technique relied on antegrade cold crystalloid cardioplegia.During OPCAB procedure the heart was immobilized with two suction based stabilizers with all peripheral anastomoses being sutured on intracoronary shunts, as described previously 2 .The postoperative outcomes of both groups were analyzed, retrospectively.
This study was approved by the Institutional Review Board of our institution.

Statistical analysis
The recorded data were statistically analyzed using Statistica 6.0 software (StatSoft, Tulsa, OK).Dependences between variables were evaluated using contingency tables.Continuous variables were compared using the t test, with a p value less than 0.05 considered statistically signifi cant.

RESULTS
The study enrolled 345 patients undergoing elective myocardial revascularization procedures, of which 173 (50.1 %) were OPCAB and 172 (49.9 %) were ONCAB.The mean ages of the patients undergoing OPCAB and ONCAB were 68.2 and 66.4 years, respectively, and they comprised 30.8 % and 36.4 % females.The postoperative results are listed in Table 2.
Three patients (1.7 %) in the OPCAB group needed intraoperative conversion to ONCAB owing to hemodynamic instability, and these patients were included in the OPCAB cohort.Table 3 lists separately the characteristics and outcomes of these patients.
The mean number of grafts was signifi cantly lower in the OPCAB group (2.9) than in the ONCAB group (3.7), with the OPCAB group having 6 patients with fi ve peripheral anastomoses and 39 patients with four grafts.Figure 1 shows the distribution of the grafts in the two groups in terms of the numbers of sutured peripheral anastomoses.The internal thoracic artery (ITA) was used in 90.7 % and 94.1 % of OPCAB and ONCAB patients, respectively, and was harvested as a skeleton in 35.3 % and 37.1 % of them.
When the ITA was harvested as a pedicle, the postoperative blood loss was signifi cantly higher in the ONCAB group than in the OPCAB group.The ITA could not be used due to intraoperative injury in three (0.8 %) of the patients.The radial artery was used as one of the conduits more often in the OPCAB group (10.4 %) than in the ONCAB group (4.6 %).There were no postoperative myocardial infarctions or hospital deaths in any of the patients.The postoperative total blood loss was signifi cantly higher in the ONCAB group.However, the frequencies of postoperative confused states, strokes, postoperative transfusions, reoperations for bleeding, and atrial fi brillation, and the durations of intubation, ICU stay, and hospital stay did not diff er signifi cantly between the two groups.The choice of on-or off -pump coronary bypass grafting -a surgeon's dilemma

DISCUSSION
According to the 2005 AHA Scientifi c Statement, both the OPCAB and standard CABG procedures usually result in excellent outcomes, with neither being considered inferior 1 .Although this recommendation is based on scientifi c evidence, it appears unlikely that exposing or not exposing a patient to extracorporeal circulation makes no diff erence.
In daily practice, a surgeon should precede depending upon his or her own results.In this study we compared the outcomes of patients undergoing OPCAB and ONCAB procedures.The approximately equal numbers (173 vs. 172) of consecutive, elective patients were operated by a single surgeon who was experienced in both OPCAB and ONCAB procedures.Signifi cantly fewer grafts were performed in the OPCAB group (2.9 vs. 3.7), which was due to the fact that patients with 1-2 vessel disease were primarily indicated for the OPCAB procedure.The only signifi cant diff erence between the two groups was the postoperative blood loss, which was higher in the ONCAB group.In contrast to previously published studies, we found no signifi cant diff erence in the durations of intubation, ICU stay, hospitalization and mortality between the groups [3][4][5][6][7][8] .Also, the frequencies of postoperative episodes of neurological complications, reoperations for bleeding, atrial fi brillations, and sternum infections did not diff er between the groups.From this study we can conclude that OPCAB procedures are safe and provide good clinical outcomes, similar to those of ONCAB operations, in a selected group of patients.The outcomes of this study favor neither of the compared techniques, and although the OPCAB group comprised more so called easy patients (good LV, less grafts) the dilemma remains.Should we continue to perform OPCAB in these patients, which is always technically more demanding, or should we just put a cross clamp and enjoy the bloodless and motionless operating fi eld?

Fig. 1 .
Fig. 1.The distribution of the grafts in the two groups (OPCAB and ONCAB) in terms of the number of sutured peripheral anastomoses.(grey, 1 anastomosis; white 2 anastomoses; black, 3 and more anastomoses)

Table 1 .
The preoperative characteristics of OPCAB and ONCAB patients.

Table 2 .
The postoperative results of OPCAB and ONCAB patients.

Table 3 .
Characteristics and outcomes of patients converted to ONCAB.