J Thorac Cardiovasc Surg 2000;119:1013-1014
© 2000 The American Association for Thoracic Surgery
Surgery For Acquired Cardiovascular Disease |
Commentary
Alfred J. Tector, MD,
Monica L. McDonald, MD,
Milwaukee, Wisconsin
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Introduction
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We compliment Kawasuji and associates on their management and results over 18 years in 101 patients with familial hypercholesterolemia and severe coronary artery disease. Seventy patients received one or more arterial bypass grafts and 30 patients have saphenous vein grafts, for an average of 2.6 grafts per patient. Postoperatively, the patients’ cholesterol levels were reduced to less than 180 mg/dL and their low-density lipoprotein cholesterol levels were reduced to less than 130 mg/dL with diet therapy and cholesterol-lowering drugs. The 13 patients who did not respond to drug therapy were treated with low-density lipoprotein apheresis.
This group of patients has premature coronary artery disease combined with high cholesterol levels and provides an excellent model to evaluate therapies to optimize results in high-risk patients. Postoperative management of patients can have an influence on the incidence of reoperation, and the importance of aggressive control of cholesterol levels should not be ignored. Aggressive lowering of low-density lipoprotein cholesterol levels was shown to decrease obstructive changes in saphenous vein grafts by 31% according to the National Heart, Lung, and Blood Institute study.
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The effect of maintaining low cholesterol levels in patients with complete arterial grafting is not known. Flaker and associates 2 showed that a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor reduced clinical events in revascularized postinfarction patients with average cholesterol levels. This fact, combined with the knowledge that control of cholesterol levels in the postoperative period halted the development of new lesions in native coronary arteries and bypass vein grafts but did not reduce the progression of vein graft lesions, has important implications. 3 It seems that lowering of cholesterol levels is also beneficial in patients with total arterial grafting, at least in part because of slowing the development of new lesions. Intensive control of cholesterol levels in the postoperative period should be started immediately to prevent the progression of disease.
Even though this study did not reveal any significant benefit from multiple arterial grafting, one would suspect that the survival and outcomes would eventually be affected in view of the low patency in the saphenous vein grafts. The fact that the internal thoracic artery (ITA) has a higher patency than venous grafts supports the importance of arterial grafts. The benefits from total arterial revascularization will not be seen unless a very large number of patients are observed for an extended length of time. Lytle and associates 4 reviewed more than 10,000 patients to show a benefit from bilateral ITA grafting.
What is not known is whether all arterial conduits are equivalent. Patency of the ITA, but not that of the radial artery, which differs in that it is a muscular artery, has proven to be superior. Further long-term studies into different forms of arterial revascularization will answer these questions.
This article demonstrates the importance of using arterial grafts combined with strict control of total and low-density lipoprotein cholesterol levels in patients undergoing coronary artery bypass grafting. Current available data on the beneficial effects of the new statin drugs only increase the importance of aggressive control of cholesterol levels in the postoperative patient. As surgeons, we must educate our patients and their family physicians on this vital issue. Striving for ways to halt progression of native and bypass graft disease may further decrease the incidence of coronary reoperations and other morbidities and enhance patient survival.
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References
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Campeau L, Hunninghake DB, Knatterud GS, et al. Aggressive cholesterol lowering delays saphenous vein graft atherosclerosis in women, the elderly, and patients with associated risk factors: NHLBI post coronary artery bypass graft clinical trial. Post-CABG Trial Investigators. Circulation 1999;99:3241-7. [Abstract/Free Full Text]
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Flaker GC, Warnica JW, Sacks FM, et al. Pravastatin prevents clinical events in revascularized patients with average cholesterol concentrations. J Am Coll Cardiol 1999;34:106-12. [Abstract/Free Full Text]
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Cashin-Hemphill L, Mack WJ, Pogoda JM, Sanmarco ME, Azen SO, Blankenhorn DH. Beneficial effects of cholestipol-Niacin on coronary atherosclerosis. JAMA 1990;264:3013-7. [Abstract]
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Lytle BW, Blackstone EH, Loop FD, et al. Two internal thoracic artery grafts are better than one. J Thorac Cardiovasc Surg 1999;117:855-72. [Abstract/Free Full Text]
12/1/105259 doi:10.1067/mtc.2000.105259
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Introduction
References