Chronic stable angina revascularization coronary artery bypass grafting
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Chronic stable angina Microchapters | ||
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Classification | ||
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Differentiating Chronic Stable Angina from Acute Coronary Syndromes | ||
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Diagnosis | ||
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Alternative Therapies for Refractory Angina | ||
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Discharge Care | ||
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Guidelines for Asymptomatic Patients | ||
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Case Studies | ||
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Chronic stable angina revascularization coronary artery bypass grafting On the Web | ||
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Editors-In-Chief: C. Michael Gibson, M.S., M.D. [1] Phone:617-632-7753; Cafer Zorkun, M.D., Ph.D. [2]; Associate Editors-In-Chief: John Fani Srour, M.D.; Smita Kohli, M.D.
Coronary Artery Bypass Grafting(CABG)
CABG is carried out to prolong life or improve its quality (see above). Prolongation of life has been shown in patients with more than 50% luminal diameter stenosis of the left main coronary artery and in those with impaired left ventricular function (left ventricular ejection fraction <40%) and critical, >70% stenosis in all three major coronary arteries or in two arteries, one of which is the proximal left anterior descending artery. The presence of a high-risk result on a noninvasive test also increases the benefit of surgery. Patients with severe left ventricular dysfunction obtain a survival benefit from CABG if the myocardium with impaired contractile function is viable (hibernating myocardium) rather than necrotic. The stenotic arteries are bypassed with an internal mammary (arterial) or saphenous vein graft. Arterial grafts have excellent long-term patency rates (90% at 10 years), whereas saphenous vein grafts show accelerated atherosclerosis with approximately 50% patency at 10 years. The use of internal mammary artery grafts is associated with a 27% reduction in 15-year mortality compared with saphenous vein grafts. The left internal mammary artery is most favorable to a graft to the left anterior descending coronary artery and the right internal mammary artery is most applicable to graft to the right coronary artery. Patients who require more than two grafts generally receive a combination of arterial and venous grafts. Minimally invasive CABG via a smaller thoractomy incision or a thorascopic approach reduces the morbidity and hospital length-of-stay. The operative mortality of CABG is about 2%. The steady improvements in perioperative care have been offset by the progressively sicker patients who are referred for this procedure. Angina pectoris is relieved in more than 90% of patients who undergo CABG. The recurrence of angina is due to graft stenosis or progression of disease in nongrafted vessels.
Clinical trial data: coronary artery bypass surgery versus medical treatment in the management of stable angina pectoris
It is well established that CABG provides more symptoms relief and survival benefits in some patients with chronic stable angina. However, the long term benefit of CABG is limited by the progression of atherosclerosis in other unbypassed vessels and stenosis of the graft itself. The CASS Trial (Coronary Artery Surgery Study) showed that more patients remained symptom-free after CABG compared to medical therapy at one year (66 versus 30 percent) and five years (63 versus 38 percent). However, by 10 years, this difference had disappeared (47 versus 42 percent). Trials from the 1970's showed that CABG offered no significant overall mortality benefits compared to medical therapy. However, several trials established the survival benefits in selected patients:
- Left main coronary artery stenosis or left main equivalent disease (defined as severe (≥70 percent) proximal left anterior descending and proximal left circumflex disease):
The Veterans Administration Cooperative Study compared a strategy of initial CABG versus deferred CABG: there was a substantial survival advantage patients assigned to initial CABG at two years (93 versus 71 percent) and at 11 years, but not at 18 years. The benefit was greatest in high-risk patients with >75 percent left main stenosis and/or left ventricular dysfunction. The CASS registry demonstrated similar results. Yusuf S et al[1] published an overview of 10-year results from randomized trials by the Coronary Artery Bypass Graft Surgery Trialists Collaboration. They found that the relative risk reduction for death provided by CABG over medical therapy alone was greater at five years for left main disease than for three vessel or one or two vessel disease (odds ratio 0.32 versus 0.58 and 0.77); the absolute survival benefit from CABG among those with left main disease was 19.3 months.
PCI for left main coronary artery stenosis: PCI has been performed in patients with angina and left main disease who are considered inoperable, at high risk for CABG, or with prior CABG and one patent graft to either the left anterior descending or circumflex artery ("protected" left main).
- Multivessel coronary disease and left ventricular dysfunction:
Reduced left ventricular function is an important determinant of prognosis in patients with stable angina and is an indication for revascularization. CABG may improve survival in patients with left ventricular dysfunction and hibernating myocardium; therefore, myocardial viability should be assessed prior to recommending CABG in patients with multivessel coronary disease and left ventricular dysfunction. CASS registry showed that survival at seven years was improved with CABG compared to medical treatment (88 versus 65 percent) in patients with an LVEF between 35 and 49 percent and had three vessel disease. No benefit from CABG could be identified in patients with one or two vessel disease.
See Also
Sources
- The ACC/AHA/ACP–ASIM Guidelines for the Management of Patients With Chronic Stable Angina [2]
- TheACC/AHA 2002 Guideline Update for the Management of Patients With Chronic Stable Angina [3]
- The 2007 Chronic Angina Focused Update of the ACC/AHA 2002 Guidelines for the Management of Patients With Chronic Stable Angina [4]
References
- ↑ Effect of coronary artery bypass graft surgery on survival: overview of 10-year results from randomised trials by the Coronary Artery Bypass Graft Surgery Trialists Collaboration. Yusuf S, Zucker D, Peduzzi P, Fisher LD, Takaro T, Kennedy JW, Davis K, Killip T, Passamani E, Norris R, et al. Lancet. 1994 Aug 27;344(8922):563-70. Erratum in: Lancet 1994 Nov 19;344(8934):1446. PMID: 7914958
- ↑ Gibbons RJ, Chatterjee K, Daley J, Douglas JS, Fihn SD, Gardin JM et al. (1999) ACC/AHA/ACP-ASIM guidelines for the management of patients with chronic stable angina: executive summary and recommendations. A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Management of Patients with Chronic Stable Angina). Circulation 99 (21):2829-48. PMID: 10351980
- ↑ Gibbons RJ, Abrams J, Chatterjee K, Daley J, Deedwania PC, Douglas JS et al. (2003) ACC/AHA 2002 guideline update for the management of patients with chronic stable angina--summary article: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on the Management of Patients With Chronic Stable Angina). Circulation 107 (1):149-58. PMID: 12515758
- ↑ Fraker TD, Fihn SD, Gibbons RJ, Abrams J, Chatterjee K, Daley J et al. (2007) 2007 chronic angina focused update of the ACC/AHA 2002 Guidelines for the management of patients with chronic stable angina: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines Writing Group to develop the focused update of the 2002 Guidelines for the management of patients with chronic stable angina. Circulation 116 (23):2762-72. DOI:10.1161/CIRCULATIONAHA.107.187930 PMID: 17998462