Correspondence

Stent Placement Compared with Balloon Angioplasty for Obstructed Coronary Bypass Grafts

N Engl J Med 1998; 338:198-199January 15, 1998

Article

To the Editor:

Savage et al. (Sept. 11 issue)1 present convincing data favoring stent placement over balloon angioplasty for obstructive coronary bypass grafts, but several caveats about important variables should be kept in mind. First, there were considerably more patients with diabetes in the angioplasty group than in the stent group (36 percent, vs. 23 percent), and angioplasty is less successful in the long term in patients with diabetes than in those without diabetes.2

Second, we do not have information about the control of diabetes, an important variable related to survival in patients with diabetes and complications of coronary artery disease.3 Third, we have no information about the patients' lipid levels and, for example, whether they were treated with inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase, which can affect survival.4

Finally, we do not know whether these patients had received therapy with beta-blockers and angiotensin-converting–enzyme inhibitors, medications that have been shown to improve survival after myocardial infarction. For more convincing conclusions, comparisons of invasive cardiologic procedures should control for all these important noninvasive variables.

Jeffrey M. Bloom, M.D.
Mission Medical Associates, San Luis Obispo, CA 93401

4 References

1. 1

   Savage MP, Douglas JS Jr, Fischman DL, et al. Stent placement compared with balloon angioplasty for obstructed coronary bypass grafts. N Engl J Med 1997;337:740-747
   Full Text | Web of Science | Medline

2. 2

   The Bypass Angioplasty Revascularization Investigation (BARI) Investigators. Comparison of coronary bypass surgery with angioplasty in patients with multivessel disease. N Engl J Med 1996;335:217-225[Erratum, N Engl J Med 1997;336:147.]
   Full Text | Web of Science | Medline

3. 3

   Malmberg K. Prospective randomised study of intensive insulin treatment on long term survival after acute myocardial infarction in patients with diabetes mellitus. BMJ 1997;314:1512-1515
   CrossRef | Web of Science | Medline

4. 4

   The Post Coronary Artery Bypass Graft Trial Investigators. The effect of aggressive lowering of low-density lipoprotein cholesterol levels and low-dose anticoagulation on obstructive changes in saphenous-vein coronary-artery bypass grafts. N Engl J Med 1997;336:153-162
   Full Text | Web of Science | Medline

Author/Editor Response

The authors reply:

To the Editor: The benefits of coronary-artery bypass surgery are often temporary. Within 10 years after surgery, about half of all vein grafts will have clinically significant atherosclerotic disease.1 In our randomized trial comparing stent placement with balloon angioplasty for obstructed coronary bypass grafts, we demonstrated an improved outcome in the short term (240 days) in patients treated with stent placement. Nevertheless, the longer-term prognosis after vein-graft intervention remains guarded because of the potential for restenosis and late progression of graft disease.2

Because of the palliative nature of transcatheter interventions in such patients, the importance of adjunctive medical therapy and risk-factor modification cannot be overemphasized. Cessation of smoking, reduction in serum lipid levels, and use of aspirin are imperative to maintain patent grafts. Dr. Bloom highlights the importance of attending to the multiple cardiac risk factors in patients who have undergone bypass surgery. For example, in our study, 64 percent of the patients in the angioplasty group and 65 percent of those in the stent group had elevated cholesterol levels (>200 mg per deciliter). Because of the randomized design, the two groups were similar with regard to all base-line characteristics except for the prevalence of diabetes, which was slightly higher in the angioplasty group. As we reported in our article, adjustment for the presence or absence of diabetes had no effect on the principal clinical and angiographic outcomes. The results were similar with the use of a stratified analysis (unpublished data), confirming the significant independent benefit of stent therapy.

Dr. Bloom also notes that the long-term outcome after angioplasty is less favorable in patients with diabetes than in those without diabetes. Unfortunately, the long-term outcome after bypass surgery is also less favorable in patients with diabetes.3 Therefore, the physician caring for a patient with diabetes and myocardial ischemia often faces a difficult problem in deciding on the course of treatment. Further research into the pathophysiology and therapy of restenosis in the setting of diabetes is clearly needed. Our preliminary studies suggest that stent placement may represent a considerable advance in transcatheter revascularization in patients with diabetes mellitus and coronary artery disease.4

Michael P. Savage, M.D.
David L. Fischman, M.D.
Jefferson Medical College, Philadelphia, PA 19107

Sheldon Goldberg, M.D.
Massachusetts General Hospital, Boston, MA 02114

4 References

1. 1

   Bourassa MG, Fisher LD, Campeau L, Gillespie MJ, McConney M, Lesperance J. Long-term fate of bypass grafts: the Coronary Artery Surgery Study (CASS) and Montreal Heart Institute experiences. Circulation 1985;72:Suppl V:V-71
   

2. 2

   Savage MP, Kim R, Fischman DL, Goldberg S. Stenting in saphenous vein grafts: progress and future challenges. J Intervent Cardiol 1997;10:145-153
   CrossRef | Web of Science

3. 3

   Barsness GW, Peterson ED, Ohman EM, et al. Relationship between diabetes mellitus and long-term survival after coronary bypass and angioplasty. Circulation 1997;96:2551-2556
   Web of Science | Medline

4. 4

   Savage MP, Fischman DL, Slota P, et al. Coronary intervention in the diabetic patient: improved outcome following stent implantation versus balloon angioplasty. J Am Coll Cardiol 1997;29:Suppl A:188A-188A abstract.