Experience and early results of second reoperations for coronary artery disease

Extraluminal atherosclerosis: an under-recognised finding in human aortocoronary venous bypass grafts

BACKGROUND

Coronary artery bypass grafting (CABG) is commonly compromised by graft atherosclerosis. Histopathologic studies confirm various forms of atherosclerosis, including positively remodelled lesions in native coronary arteries but there are no histopathologic reports of extraluminal atherosclerosis in vein grafts.

METHODS

We prospectively investigated the histopathologic presence and pattern of extraluminal atherosclerosis in human old vein grafts in a two-year interval among patients undergoing redo-CABG at three university hospitals in Tehran. We separately documented clinical and angiographic findings.

RESULTS

We evaluated 100 segments from 20 human old vein grafts obtained during the redo CABG. All but four segments demonstrated some degrees of luminal narrowing. Luminal atherosclerotic plaques were detectable in 61 segments. We detected extraluminal atheroscleoris in seven segments. Mean vessel wall thickness was greater in segments containing extraluminal plaques (1.41±0.26 mm versus 0.91±0.04 mm, P=0.008). Angiographic findings had a modest correlation with presence or absence of luminal atheromatous lesions (Spearman's rho: 0.331, P=0.007). Angiographic degree of stenosis could not predict the presence of positively remodelled atherosclerotic plaques (Spearman's rho: -2.21, P=0.073).

CONCLUSION

Previous studies suggested positive remodelling in vein grafts. Out study provides histopathologic evidence on extraluminal atherosclerosis in human aortocoronary vein grafts.

A New Anatomic Score for Prognosis After Cardiac Catheterization in Patients with Previous Bypass Surgery

OBJECTIVES

The purpose of this study was to determine the value of a new anatomic score for prognosis after diagnostic catheterization in patients with previous coronary artery bypass grafting (CABG).

BACKGROUND

Previous CABG patients comprise a growing proportion of patients with coronary artery disease (CAD). Whereas prognostic scores are available to adjust for native CAD, there are no comparable scores for patients with previous CABG.

METHODS

We studied 3,178 previous CABG patients (2,729 in a training set) who underwent cardiac catheterization. With a Cox model to develop relative weights in the training set, we created a graft index that adjusted native anatomy for territories with grafts free of significant (> or =75%) stenoses. Scaling the regression coefficients by the maximum coefficient created an index ranging from 0 to 100, where 100 was three-vessel CAD with no patent grafts.

RESULTS

The graft index was significantly associated with all-cause death (chi-square = 121.9, p < 0.001). In combined models, the index was more strongly associated with all-cause death than either number of diseased vessels (chi-square = 68.0 and 1.7, respectively) or the Duke CAD index (chi-square = 54.3 and 9.5, respectively). In models for death using an independent validation set, the index was also associated more strongly than either native disease descriptors. In a model including other clinical variables, the graft index remained significantly associated with all-cause death (chi-square = 40.1, p < 0.001).

CONCLUSIONS

For previous CABG patients, the Duke graft index was significantly more associated with prognosis than native anatomy alone and quantifies the effect of patent grafts on survival. This tool has the potential to help determine prognosis and inform the referral of post-CABG patients to repeat revascularization procedures.

Third-time coronary artery bypass grafting

BACKGROUND

In this study we analyze the short- and long-term results, and the clinical, functional, and subjective status of patients after a second coronary reoperation (RE-RE-CABG).

METHODS

The perioperative data of 33 consecutive patients undergoing RE-RE-CABG (1987 to 1998) were studied. Follow-up information was obtained from our follow-up databank. A cross-sectional follow-up was conducted, with additional functional evaluation by the Duke Activity Status Index (DASI), and patients' evaluations of their life situation were registered.

RESULTS

Perioperative mortality was 2 of 33 patients (6%). During the follow-up (mean 51.6 months) 5 patients died. The 26 survivors showed a significant decrease in New York Heart Association class from 3.6+/-0.4 preoperatively versus 2.2+/-0.6 postoperatively. The mean Duke Activity Status Index score was 29.30+/-16.34 (range 7.22 to 48.9). In all, 18 of 26 patients (70%) were declared to have benefitted from the RE-RECABG.

CONCLUSIONS

The significant improve in New York Heart Association class and good postoperative functional capacity, justified the RE-RE-CABG. However, patients must be informed about the limitations of this procedure.

Aortocoronary saphenous vein graft disease: pathogenesis, predisposition, and prevention

Aortocoronary saphenous vein graft disease, with its increasing clinical sequelae, presents an important and unresolved dilemma in cardiological practice. During the 1st month after bypass surgery, vein graft attrition results from thrombotic occlusion, while later the dominant process is atherosclerotic obstruction occurring on a foundation of neointimal hyperplasia. Although the risk factors predisposing to vein graft atherosclerosis are broadly similar to those recognized for native coronary disease, the pathogenic effects of these risk factors are amplified by inherent deficiencies of the vein as a conduit when transposed into the coronary arterial circulation. A multifaceted strategy aimed at prevention of vein graft disease is emerging, elements of which include: continued improvements in surgical technique; more effective antiplatelet drugs; increasingly intensive risk factor modification, in particular early and aggressive lipid-lowering drug therapy; and a number of evolving therapies, such as gene transfer and nitric oxide donor administration, which target vein graft disease at an early and fundamental level. At present, a key measure is to circumvent the problem of vein graft disease by preferential selection of arterial conduits, in particular the internal mammary arteries, for coronary bypass surgery whenever possible.

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

Reoperative (redo) coronary artery bypass grafting is an efficient treatment for patients with progressive coronary artery disease and those with conduit failure. Previous studies have demonstrated that a short time interval between primary and redo coronary artery bypass grafting is associated with a significantly higher mortality rate. In the present report this particular group have been specifically evaluated. Between 1 January 1990 and 1 October 1994, 383 consecutive patients underwent redo coronary artery bypass grafting. Thirty-three patients (8.6%) were operated on at < or = 1 year (group 1) and 350 patients at > 1 year after the primary bypass (group II). The main indications for redo in group I were graft failure (58%), incomplete revascularization (39%) and progress of disease (3%); respective values in group II were 26% 15%, and 23%. In addition, 36% of patients in group II had combinations of complications. Patient characteristics did not differ between groups, except a higher incidence of insulin-dependent diabetes in group I (P < 0.05). There was a higher incidence of left main stem stenosis of > 70% in group I (P < 0.05). Group I patients had a longer aortic cross-clamping time and needed thromboendarterectomy and patching of coronary vessels more often than did those in group II (P < 0.05). The internal mammary artery had been more frequently used at the primary coronary artery bypass grafting in group I (P < 0.01). The overall mortality rate was 8.9%; that in group I was 18% and in group II, 8% (P < 0.05). There was a higher incidence of non-fatal myocardial infarction and a need for prolonged ventilatory support (> 24 h) in group I. Other postoperative complications did not differ. Significant risk factors for mortality in group I were preoperative Canadian Cardiovascular Society class > or = 3, unstable angina, need for urgent operation and left ventricular ejection fraction < 40%, and > or = 70% left main stem stenosis. In group II, the risk factors were: unstable angina, urgent operation, left ventricular ejection fraction < 40%, internal mammary artery not used at primary coronary artery bypass grafting and the need for coronary thromboendarterectomy. The 3-year survival and cardiac event-free survival did not differ between the groups. This study has confirmed that early redo coronary artery bypass grafting (< or = 1 year from primary bypass) is associated with an increased operative risk.

Long-term clinical outcome after stent implantation in saphenous vein grafts

OBJECTIVES

We sought to determine the role of stent implantation in vein grafts by evaluating the long-term clinical outcome and estimated event-free survival at 5 years in 62 patients and by comparing our data with those of other treatment modalities previously reported.

BACKGROUND

Patients with recurrent angina after coronary artery bypass graft surgery pose a problem. Stent implantation has been advocated in an effort to avoid repeat operation and to address the limitations of balloon angioplasty.

METHODS

Patients undergoing stenting of a vein graft were entered into a dedicated data base. They were screened for death, infarction, bypass surgery and repeat angioplasty. Procedure-related events were included in the follow-up analysis. Survival and event-free survival curves were constructed by the Kaplan Meier method.

RESULTS

A total of 93 stents (84 Wallstent and 9 Palmaz-Shatz) were implanted in 62 patients. During the in-hospital period seven patients (11%) sustained a major cardiac event: two deaths (3%), two myocardial infarctions (3%) and three urgent bypass surgeries (5%). The clinical success rate, therefore, was 89%. During the follow-up period (median 2.5 years, range 0 to 5.9), another five patients (8%) died, 14 (23%) sustained a myocardial infarction, 12 (20%) underwent bypass surgery, and 14 (23%) underwent angioplasty. The estimated 5-year survival and event-free survival rates (free from infarction, repeat surgery and repeat angioplasty) were (mean +/- SD) 83 +/- 5% (95% confidence interval [CI] 73% to 93%) and 30 +/- 7% (95% CI 16% to 44%), respectively.

CONCLUSIONS

The in-hospital outcome of patients who underwent stent implantation in a vein graft is acceptable, but the long-term clinical outcome is poor. It is unlikely that mechanical intervention alone will provide a satisfactory or definite answer for the patient with graft sclerosis over the long term.