The impact of a short interval ( < or = 1 year) between primary and reoperative coronary artery bypass grafting procedures

Reoperative off-pump coronary artery bypass grafting: current outcomes, concerns and controversies

Increasing numbers of patients have undergone coronary artery bypass grafting in the last four decades. As a result, the incidence of reoperative coronary artery bypass grafting is rising. Reoperative procedures pose several technical difficulties and are associated with increased operative risks, which exceed those of the initial revascularization. As the incidence of reoperative procedures is increasing so is the experience of reoperative coronary artery bypass grafting, with the resultant evolution of several alternative strategies to lower the operative risks. These strategies include alternative techniques for re-entry, strict avoidance of graft manipulation to minimize the risk of graft atheroembolism, and modification of the method of myocardial protection, depending on the status of the native coronary circulation and the patency of venous or arterial grafts. Off-pump coronary artery bypass grafting is one such technique that, through the avoidance of inherent risks of cardiopulmonary bypass, has the potential to reduce the morbidity associated with reoperative coronary artery bypass grafting. This article evaluates the current outcomes of reoperative off-pump coronary artery bypass grafting, and highlights the concerns and controversies associated with this strategy.

Is Reoperation Still a Risk Factor in Coronary Artery Bypass Surgery?

BACKGROUND

Hospital mortality for reoperative coronary artery bypass grafting (CABG) is approaching that of primary CABG. This raises two questions: (1) has experience neutralized the risk of reoperation attributable to its greater difficulty, or (2) has experience neutralized the risk attributable to the higher-risk profile of reoperative patients?.

METHODS

From 1990 to 2003, 21,568 CABG procedures were performed, of which 4,518 (21%) were reoperations: 3,919 first, 552 second, 43 third, 3 fourth, and 1 fifth. Reoperative patients had a higher-risk profile than primary patients, with more vascular disease, left ventricular dysfunction, and coronary artery disease (all p < 0.0001). Logistic regression was used to identify factors associated with hospital death and to develop a propensity score for reoperation, which was used to (1) adjust multivariable analyses of death and (2) compare outcomes in matched patients.

RESULTS

Hospital mortality was 4.3% (168 of 3,919) for first reoperation, 5.1% (28 of 552) for second, and 6.4% (3 of 47) for third or more, compared with 1.5% (263 of 17,050) for primary operations. Risk of both primary and reoperative CABG decreased with experience (p > 0.0002); however, reoperative risk fell markedly in the mid-1990s. In both the overall and matched-pairs analyses, reoperation was a risk factor before 1997 (p < or = 0.008), but not after (p = 0.2). Reoperation within 1 year of previous CABG increased risk (p < 0.0001). Risk attributable to left ventricular dysfunction decreased with experience (p = 0.05).

CONCLUSIONS

Hospital mortality for reoperative CABG has been consistently higher than for primary operation, but this difference has narrowed considerably. Patient characteristics, not reoperation itself, now have greater influence.

Complete myocardial revascularization: between myth and reality

Myocardial revascularization in patients with multi-vessel coronary artery disease may be accomplished, by percutaneous interventions or surgery, either on all diseased lesions or directed to selectively targeted coronary segments. The extent of planned revascularization is often a major determinant of treatment strategy. Revascularization of all diseased coronary segments-complete myocardial revascularization-has a potential long-term benefit, but is more complex and may increase in-hospital untoward events. Revascularization may otherwise be incomplete, either because of the operator's inability to treat all diseased coronary segments or by choice of deciding to selectively revascularize only large areas of myocardium at risk. Although incomplete revascularization may negatively affect long-term outcomes, it may be, when wisely chosen, the preferred treatment strategy in selected patient categories because of its lower immediate risks. The patient's clinical status, ventricular function, and the presence of co-morbidities may orient clinical decisions in favour of incomplete revascularization.

How to avoid problems in redo coronary artery bypass

BACKGROUND

Redo cardiac surgery still carries higher mortality and increased morbidity as compared with primary coronary revascularizations. Various steps can be taken to decrease the incidences of adverse outcomes. From our experience, we have accumulated safe steps to be taken during the surgical procedure to reach a positive outcome.

METHODS

We reviewed our own experience of redo coronary artery bypass surgery (CABG) at two institutions during the last 4 years. Though the surgeons were the same at both institutions, because of institutional variability of patient referrals, operative equipment, anesthesia management, and preoperative care, we kept the data separate. Five surgeons performed CABG with almost similar myocardial preservation techniques; however, the surgical skill varied slightly depending on the seniority and clinical experience. We performed 433 redo coronary artery revascularizations at one institution and 201 in the second institution. Fifteen percent of these patients also had additional procedures, such as valve repair, valve replacement, or aneurysm resection. In this patient group, 160 patients underwent either urgent or emergent CABG. Urgent surgery was defined as patient revascularization during the same admission as cardiac catheterization, and emergency surgery was defined as a patient undergoing surgery on the same day as the catheterization, especially when hemodynamic instability was present. The total mortality was 7%, while the elective redo CABG mortality was 3%. The length of stay ranged from 8.5 to 12.6 days. The morbidity included perioperative stroke in 18 patients and nonfatal perioperative myocardial infarction (MI) in 19 patients. Major factors contributing to the mortality were stroke, perioperative bleeding and exploration, renal failure, respiratory failure, and malnutrition.

CONCLUSION

We outlined the precautions and safe surgical approaches to be undertaken during redo CABG for a successful outcome.

Long-term follow-up after coronary artery bypass grafting reoperation

BACKGROUND

Coronary artery bypass grafting (CABG) reoperation is being performed with increasing frequency.

OBJECTIVE

To determine the clinical outcome and the long-term results of a second CABG.

SETTING

An 1100-bed urban university-affiliated hospital.

DESIGN

Retrieval of data on selected parameters from medical records before surgery and prospective follow-up afterwards.

PATIENTS AND METHODS

We studied the outcomes of 498 consecutive patients who underwent CABG reoperation in our institution from January 1978 to December 1989 and who were followed postoperatively. Their perioperative mortality, morbidity, and long-term follow-up results were re-evaluated. The end points of the study were December 1997, 15 years of follow-up, or the patient's death.

RESULTS

The perioperative mortality rate was 3%. The cumulative survival rates were 90.1%, 74%, and 63.4% at the 5-year, 10-year, and 15-year follow-ups, respectively. The cardiac event-free survival rates were 91.5%, 83.4%, and 67.8% at the 5-year, 10-year, and 15-year follow-ups, respectively. The risk factors adversely affecting long-term survival were advanced age, hypertension, and a low left ventricular ejection fraction (LVEF).

CONCLUSIONS

The long-term results of cumulative survival and cardiac event-free survival in patients who underwent CABG reoperation are good. Although this reoperation is safe overall, advanced age, hypertension, and a decreased LVEF significantly increase the surgical risk.

Preoperative intraaortic balloon pump enhances cardiac performance and improves the outcome of redo CABG

BACKGROUND

Reoperative coronary artery bypass grafting (redo CABG) is associated with an increased operative risk compared with primary CABG. Because the hospital mortality in redo CABG is known to be influenced by poor left ventricular function (left ventricular ejection fraction < or = 0.40), unstable angina, and left main stem stenosis greater than or equal to 70%, a preoperative intraaortic balloon pump (IABP) support could be beneficial to improve the outcome in high-risk redo CABG.

METHODS

Between June 1994 and October 1996, 48 high-risk patients underwent redo CABG and were randomized into the following groups: group 1 (24 patients) who received preoperative IABP treatment on average 2 hours before cardiopulmonary bypass, and group 2 (24 patients) who received no preoperative IABP and served as controls. Mean age was 65 years and 90% (43 patients) were men. Forty-one patients had preoperative left ventricular ejection fraction less than or equal to 0.40 (85%), 38% (18 patients) had left main stem stenosis greater than or equal to 70%, and 54% (26 patients) had unstable angina preoperatively. Preoperative patient characteristics did not differ between the groups.

RESULTS

The time on cardiopulmonary bypass was shorter in group 1, 86 versus 110 minutes (p = 0.006). There were no hospital deaths in group 1, but four deaths occurred in the control group (p = 0.049). Cardiac index rose significantly preoperatively after introduction of the IABP in group 1. Cardiac index was significantly higher postoperatively in group 1 compared with group 2 and remained significantly higher during the first 24 hours after cardiopulmonary bypass. Significantly fewer patients in the IABP group had postoperative low cardiac output (4 versus 13 patients). Nine patients in group 2 required IABP support postoperatively for 4.1 +/- 1.7 days. Only 2 patients in group 1 needed IABP postoperatively, and their IABPs were successfully removed on the first postoperative day. The preoperative IABP-supported patients had a shorter intensive care unit stay, 2.4 +/- 0.8 days compared with group 2, 4.5 +/- 2.2 days (p = 0.007), as well as a shorter hospital stay. The preoperative IABP treatment was found to be cost-effective.

CONCLUSIONS

Preoperative treatment with IABP in high-risk redo CABG patients is an effective modality to prepare these patients to have their myocardial revascularization in an as nonischemic situation as possible, which resulted in a significantly lower hospital mortality, fewer instances of postoperative low cardiac output, and shorter stays in both the intensive care unit and the hospital.