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Evidence summaries

The Effect of Coronary Artery Bypass Graft Surgery (Cabg) on Survival

A strategy of initial CABG is associated with lower mortality and lower rate of myocardial infarction than a strategy of medical management alone (with delayed surgery if necessary) in high-risk and medium-risk patients with stable coronary disease. Level of evidence: "A"

A systematic review 1 including 7 studies with a total of 2 649 subjects with stable coronary disease was abstracted in DARE. 93.7% of the patients assigned to CABG underwent surgery. 37.4% of patients assigned medical treatment crossed over to surgery. The crossover rate at 5 years was 42% for patients with left main artery disease, 29% for those with three-vessel disease, and 19% among patients with one or two diseased vessels.

The overall mortality was lower in CABG group than in patients assigned to medical therapy, with an overall odds ratio of 0.61 (95% CI 0.48 to 0.77) at 5 years, 0.68 (0.56 to 0.83) at 7 years, and 0.83 (0.70 to 0.98) at 10 years. The odds ratio for total mortality at 5 years was 0.32 (0.15 to 0.70) for patients with left main artery disease, 0.58 (0.42 to 0.80) for patients with three-vessel disease, and 0.77 (0.51 to 1.15) for one or two vessels disease. The treatment effects of CABG were similar for patients with normal or abnormal left-ventricular function, and were similar among patients with different severity of angina classes. The odds ratio for total mortality at 5 years was 0.50 (0.35 to 0.72) for patients at high risk, 0.63 (0.39 to 1.01) for those with medium risk, and 1.18 (0.51 to 2.71) for patients at low risk

A topic in Clinical Evidence 2 summarizes the evidence on the effectiveness of CABG versus medical treatment. RCTs performed up to the mid 1980s found a greater risk of death in the first year but a reduced risk at 5 - 10 years. A recent RCT 3 using modern techniques with optimal background medical treatment found that revascularisation decreased mortality at 2 years (absolute risk of death 1.1% with routine revascularisation vs 6.6% and 4.4% in the two medical treatment groups). Revascularization mortality or rates of myocardial infarction at 1 and 2 years vs medical treatment (AR of myocardial infarction or death 4.7% with revascularisation versus 8.8% with symptom guided treatment vs 12% with symptom plus electrocardiogram guided treatment).

    References

    • Yusuf S, Zucker D, Peduzzi P, Fisher LD, Takaro T, Kennedy JW, Davis K, Killip T, Passamani E, Norris R. 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. Lancet 1994 Aug 27;344(8922):563-70. [PubMed][DARE]
    • Sudlow C, Lonn E, Pignone M, Ness A, Rihal C. Secondary prevention of ischaemic cardiac events. Clin Evid 2002 Jun;(7):124-60. [PubMed]
    • Davies RF, Goldberg AD, Forman S, Pepine CJ, Knatterud GL, Geller N, Sopko G, Pratt C, Deanfield J, Conti CR. Asymptomatic Cardiac Ischemia Pilot (ACIP) study two-year follow-up: outcomes of patients randomized to initial strategies of medical therapy versus revascularization. Circulation 1997 Apr 15;95(8):2037-43. [PubMed]

Primary/Secondary Keywords