Coronary Artery Bypass Grafting (CABG): Reassessing Efficacy, Safety, and Cost

David K. Cundiff

In This Article

Randomized Studies Comparing Survival With CABG Vs Medical Treatment

To compare medical and surgical management of CAD, 3 major studies -- 2 in the United States and 1 in Europe -- were begun in the early 1970s.[3,5,6] Data from 4 smaller randomized studies have been added and analyzed together by meta-analysis.[7] Analyzing these 7 studies together showed a significant survival advantage with CABG at 5 years (89.8% vs 84.2%, P < .0001) and 10 years (73.6% vs 69.5%, P = .03). Subgroup analysis showed that patients with 1- and 2-vessel disease and no left anterior descending (LAD) stenosis had no survival benefit from CABG (RR, 1.05; 95% confidence interval, 0.58-1.90). Only patients with > 50% stenoses in LAD, "LAD equivalent" (> 70% stenoses of both proximal LAD and proximal left circumflex arteries), and 3-vessel disease had survival benefit.[7,8,23]

In the Veterans Administration Medical Centers CABG vs medical treatment trial, the survival advantage with CABG difference completely evaporated by 12 years; and, subsequently, up to 18 years, the groups had virtually identical survival.[3] Although the CASS reported that there was no overall significant difference in survival between the medically and surgically treated groups at 5 or 10 years, the subset of patients with left ventricular ejection fraction less than 50% treated surgically had a statistically significant difference in survival (61% vs 79%) at 10 years. (P < .01).[6] No further follow-up was reported to see if this difference in survival continued longer.

In the 1970s and 1980s, studies tested whether CABG would improve the survival in patients with CAD who had AMIs within a few hours to days. These trials showed no better and possibly lower survival rates with CABG than with conservative treatment, so emergency CABG for AMI was virtually abandoned.[24,25] The current American College of Cardiology/American Heart Association guidelines include no class 1 indications for CABG in ST-segment elevation (Q-wave) myocardial infarction.[9,23]

Randomized studies have been done with patients admitted to the hospital with unstable angina to see if they may live longer with CABG. The VA Study of Unstable Angina found no overall benefit from surgery.[26,27] However, they discovered a statistically significant difference favoring CABG at 8 years in the high-risk subgroup (P = .03) and a statistically significant advantage favoring medical treatment in the low-risk subgroup (P = .022).[26]


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