Heart Care Info - Heart Disease Prevention & Treatment

The Year in Cardiovascular Surgery

DH Adams, J Chikwe, F Filsoufi... - Journal of the ..., 2011 - Am Coll Cardio Found* Reprint requests and correspondence: Dr. David H. Adams, Department of Cardiothoracic Surgery, The Mount Sinai Medical Center, 1190 Fifth Avenue, Box 1028, New York, New York 10029 (Email: david. adams {at} mountsinai. org

Comment Endoscopic vein harvesting in patients undergoing CABG has become popular during the last decade because of fewer wound complications, better cosmesis, decreased post-operative pain, and overall improved patient satisfaction. Previous studies comparing endoscopic versus open vein harvesting mainly have focused on early outcomes and have reported similar results between these 2 techniques. This secondary analysis from the PREVENT IV trial showed that endoscopic vein graft harvesting may be associated independently with vein graft failure at 1 year and major adverse clinical events at 3 years. Confounding factors that were not accounted for in this study include on- versus off-pump techniques, the quality of the vein grafts, the quality of the distal targets, or the experience of endoscopic harvesters. The overall vein graft failure rate was higher in the PREVENT IV trial compared with most previous reports.

The authors emphasize the need for mechanistic studies to identify the potential injury mechanisms associated with endoscopic vein harvesting (40). One such study comparing endoscopic and open vein harvesting found that the endoscopic technique was associated with saphenous vein endothelial damage, reduced nitric oxide production, and decreased calcium mobilization in response to bradykinin (41). These alterations in saphenous vein structure and function associated with endoscopic harvesting potentially may explain the worse outcomes reported in this secondary analysis of the PREVENT IV trial. A randomized trial is warranted to clarify further the potential short-term benefits versus long-term risks of endoscopic vein harvesting in CABG patients.

Intraoperative completion angiography after CABG and hybrid revascularization. The outcomes of 366 consecutive patients who underwent CABG with (n = 112) or without (n = 254) concomitant PCI during the same procedure (hybrid) in a single institution were reviewed. All patients underwent a completion angiography before chest closure. The hybrid CABG and PCI procedure was planned in 67 patients (60%), whereas 45 patients (40%) underwent an unplanned hybrid procedure based on intraoperative findings. The indications for planned hybrid procedures were: minimizing surgical risk (n = 32), poor conduits (n = 3), ungraftable vessels (n = 29), or stenting of the left subclavian artery (n = 3). The indications for unplanned hybrid were: graft defects (n = 43), poor conduits (n = 1), or ungraftable vessels (n = 2).

Clinical outcomes were similar between the 2 groups. The operative mortality was 2.6% (n = 3) in the hybrid group versus 1.5% (n = 4) in the conventional CABG group (p = 0.33). The administration of higher dose clopidogrel in the hybrid group was not associated with increased post-operative chest tube output. In addition, the rate of reoperation for bleeding was not different between the groups. One patient in the hybrid group had acute post-operative in-stent thrombosis that was associated with a fatal outcome. Operating room time and costs were higher in the hybrid group. Completion angiography showed 12% of grafts (97 of 796) to have important defects. These defects were as follows: conduit defects (n = 54, 6.8%), anastomotic defects (n = 30, 3.7%), and target vessel errors (n = 13, 1.6%). Defects were repaired with minor adjustment of the graft (n = 22, 3%), with unplanned PCI (n = 48, 6%), or with surgical revision (n = 27, 3.4%).

Comment An increasing number of surgeons use technologies such as the transit time flow meter to assess intraoperative graft patency, particularly in patients undergoing off-pump CABG procedures. This study suggests that intraoperative completion angiography may be a valuable tool that can provide significant information with major clinical implications. The Vanderbilt group pioneered the concept of hybrid operating strategies in which a CABG or valve operation is completed by a concomitant PCI procedure. Although this 1-stop hybrid concept may be useful in a select group of patients, additional studies are necessary to determine further its role in daily clinical practice.

Pre-operative clopidogrel administration in patients with acute coronary syndromes undergoing CABG. The outcome of 1,520 patients with non ST-segment elevation acute coronary syndromes requiring CABG was reviewed in a subgroup analysis of the ACUITY (Acute Catheterization and Urgent Intervention Triage strateg Y) trial (42). Outcomes in clopidogrel-exposed patients (n = 773, 51%) were compared with those of patients not exposed to this agent before surgery (n = 747, 49%). Baseline patient characteristics were similar between the 2 groups. Of the 773 patients exposed to clopidogrel, 73 received it before hospitalization, 157 received it before hospitalization and in the hospital, and 543 patients received clopidogrel in the hospital only. Of these 773 patients, 524 (67.8%) patients underwent CABG fewer than 5 days after the last clopidogrel dose and 249 (32.2%) patients underwent CABG more than 5 days after the last clopidogrel dose. Clopidogrel-exposed patients had fewer composite ischemic events defined as death, myocardial infarction, or unplanned revascularization at 30 days (12.7% vs. 17.3%, p = 0.01). In multivariate analysis, pre-operative clopidogrel administration was an independent predictor of reduced 30-day composite ischemia (odds ratio: 0.67, p = 0.001). The rates of non CABG-related major bleeding (3.4% vs. 3.2%, p = 0.87), blood transfusion (38.4% vs. 38.4%, p = 1), and reoperation for bleeding (1.3% vs. 1.3%, p = 0.94) were similar in those patients who did and did not receive clopidogrel before CABG. In the cohort of clopidogrel-exposed patients, the rate of ischemia and bleeding was slightly higher in the group of patients who underwent CABG within 5 days after the discontinuation of the treatment.

Comment This subgroup analysis from the ACUITY trial showed that upstream administration of clopidogrel in patients with non ST-segment elevation acute coronary syndromes requiring urgent cardiac catheterization and referred for CABG is beneficial and is associated with a significant reduction in post-operative ischemic events. Moreover, this clinical benefit was not compromised by an increased rate of major bleeding or blood transfusion in the clopidogrel-exposed group of patients. The latter events occurred, however, at a modestly higher rate in the group of patients who underwent CABG fewer than 5 days after the discontinuation of this medication. An accompanying editorial emphasized that these findings support the current ACC/AHA guidelines for upstream clopidogrel administration in all non ST-segment elevation acute coronary syndromes patients and ACC/AHA and Society of Thoracic Surgeons guidelines for a 5-day waiting period after the termination of clopidogrel before proceeding with CABG unless there is an urgent or emergent indication for the procedure (43). Additional studies are required to understand better this protective effect of pre-operative clopidogrel administration.

Effect of prior PCI on the outcome of CABG. The outcomes of 29,928 patients undergoing primary CABG between 2000 and 2005 in 8 cardiac centers were reviewed (44). Patients were divided into 3 groups: no previous PCI (n = 25,752, 86%), 1 previous PCI (n = 3,078, 10.3%), and 2 or more previous PC Is (n = 1,098, 3.7%). Risk-adjusted multivariate analysis showed that 2 or more previous PC Is were associated with a significant increase in hospital mortality (OR: 2.0, p = 0.0005) and major adverse cardiac events (OR: 1.5, p = 0.01).

In another retrospective study, the outcomes of 1,758 diabetic patients who underwent primary CABG between 2001 and 2006 were analyzed (no previous PCI: n = 1,537, 87.5%; previous PCI: n = 221, 12.5%) (45). After risk adjustment, patients with a history of PCI had an increased operative mortality (OR: 4.0), rate of perioperative MACE (OR: 2.7), and decreased age-adjusted survival at 2 years (93.4% vs. 87.4%, p < 0.01).

Comment There has long been a feeling among surgeons that previous PCI may complicate CABG procedures. The results of these studies are in agreement with some earlier smaller studies. Multiple attempts at reintervention with PCI, particularly in diabetic patients, probably should be avoided in patients who are reasonable CABG candidates. Although there are several possible hypotheses to explain the observations, such as the existence of a more progressive form of the atherosclerotic disease in patients with prior PCI undergoing CABG, post-stenting inflammatory response with endothelial dysfunction, or distal implantation of a bypass graft forced by the presence of multiple proximal stents, the mechanism(s) by which prior PCI compromises the outcomes of CABG remain undetermined. An invited editorial questioned if these results should dampen enthusiasm toward hybrid approaches and reinforced that patients requiring complex revascularization may be better served by primary CABG (46).