Angina: early coronary artery bypass grafting lowers mortality.

Clinical bottom line (level 1a)

  1. A third of patients with stable coronary artery disease on medical therapy are dead within 10 years.
  2. Early coronary artery bypass graft surgery reduces total mortality compared with initial medical therapy in patients with stable coronary heart disease (NNT = 18 at 5 years) (NNT = 26 at 10 years) .
  3. CABG is relatively safe- only 3% die.
  4. Patients at high risk have most benefit:
    • left main artery disease (NNT = 5 at 5 years)
    • severe angina (NNT = 12 at 5 years)
    • poor left ventricular function (NNT = 12 at 5 years)
    • abnormal exercise tolerance test (NNT = 14 at 5 years)
    • 3-vessel disease (NNT = 15 at 5 years)
  5. Patients with one or two vessels disease do not have a clear reduction in mortality.
Yusuf et al: Lancet 1994; 344: 563-570
Expires June 2003

The study

Systematic review of randomised controlled trials of
  • Patients: stable coronary artery disease (stable angina not severe enough to necessitate surgery on grounds of symptoms alone, or myocardial infarction)
  • Intervention: coronary artery bypass grafting (CABG) compared with medical therapy
  • Outcome: mortality
Articles found in all using MEDLINE, no stated dates (search terms: not detailed ) and scanning bibliographies of relevant papers, and consulting with experts. All principal investigators of identified studies were invited to participate in the collaborative effort and were asked if any relevant trials were missed.

Selection criteria: as above
Appraisal criteria: not detailed
Articles excluded if: not clearly stated

Seven studies involving 1324 patients assigned to CABG and 1325 to medical management were included. Mean age was 51 years. 10% had one-vessel disease; 32% 2-vessel disease; 50% 3-vessel disease; 6.6% left main artery disease
No test for heterogeneity was performed

The evidence

Outcome Time to outcome CER OR
(95% CI)		 NNT
(95% CI)
mortality 5 years 210/
(15.8%)		 0.61
(0.48 to 0.77) 		18
(13 to 31)
mortality 7 years 288/
(21.7%)		 0.68
(0.56 to 0.83) 		17
(12 to 33)
mortality 10 years 404/
(30.5%)		 0.83
(0.70 to 0.98) 		26
(14 to 230)
mortality with 1 vessel disease 5 years /
(9.9%)		 0.54
(0.22 to 1.33) 		23
(NNT = 13 to infinity;
NNH = 35 to infinity)
mortality with 2 vessel disease 5 years /
(11.7%)		 0.84
(0.54 to 1.32) 		59
(NNT = 20 to infinity;
NNH = 31 to infinity)
mortality with 3 vessel disease 5 years /
(17.6%)		 0.58
(0.42 to 0.80) 		15
(11 to 33)
mortality with left main artery disease 5 years /
(36.5%)		 0.32
(0.15 to 0.70) 		5
(4 to 13)
mortality with exercise test status missing 5 years /
(17.4%)		 0.69
(0.45 to 1.07) 		21
(NNT = 11 to infinity;
NNH = 100 to infinity)
mortality with exercise test status normal 5 years /
(11.6%)		 0.78
(0.45 to 1.35) 		43
(NNT = 17 to infinity;
NNH = 29 to infinity)
mortality with exercise test status abnormal 5 years /
(16.8%)		 0.52
(0.37 to 0.72) 		14
(10 to 24)
mortality with normal left ventricular function 5 years /
(13.3%)		 0.61
(0.46 to 0.81) 		21
(15 to 44)
mortality with poor left ventricular function 5 years /
(25.2%)		 0.59
(0.39 to 0.91) 		12
(7 to 58)
mortality with class 0-II angina 5 years /
(12.5%)		 0.63
(0.46 to 0.87) 		24
(16 to 69)
mortality with class III-IV angina 5 years /
(22.4%)		 0.57
(0.40 to 0.81) 		12
(8 to 29)

  • a priori subgroup analysis:
    • vessels diseased (>50% stenosis)
    • left main artery disease
    • exercise tolerance test
  • 94% of patients assigned to CABG had surgery, and 37% of patients assigned to medical treatment crossed over to surgery.
  • Perioperative mortality with CABG (to 30 days) was 40/1240 (3.2%: 95% CI: 2.2% to 4.2%).

Comments

  1. CABG may prolong survival in low-risk patients, but the degree of benefit is small enough that the choice of therapy should rest more on anticipated effects on the symptoms, quality of life and cost-effectiveness.

Citation

  1. Yusuf S, Zucker D, Peduzzi R, et al: 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. Lancet 1994; 344: 563-570
Search Terms: unstable angina in Best Evidence
Contributor: Chris Ball and Clare Wotton, June 2000
Reviewer: William Rhoton

Clinical Question.
Patient stable coronary artery disease
Intervention or Exposure coronary artery bypass grafting
Comparison medical therapy
Outcome mortality