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Outcomes of off-pump versus on-pump coronary artery bypass grafting: Impact of preoperative risk

Selected in The Journal of Thoracic Cardiovascular Surgery by S. Head

References

Authors

Polomsky M, He X, O’Brien SM, Puskas JD

Reference

J Thorac Cardiovasc Surg 2013;145:1193-8

Published

May 2013

Link

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My Comment

Background

There is an ongoing debate whether off-pump coronary artery bypass grafting (CABG) without the use of cardiopulmonary bypass results in significantly lower rates of procedural complications as opposed to on-pump CABG. Although over 60 randomized trials have been performed, these have been limited by a relatively low sample size and were not powered to detect small, yet important, differences in rates of procedural mortality, stroke and myocardial infarction.

It furthermore remains unclear whether low-or-high risk patients benefit more by off-pump surgery, and whether results are dependent on center volume or operating surgeon.

Results

  • Included all patients that underwent nonemergency, isolated CABG between 01/2005 and 12/2010 in the STS database
  • 876,081 patients were analyzed: 689,943 and 186,138 patients who underwent on-pump and off-pump CABG, respectively
  • Endpoints: mortality, stroke, acute renal failure, any mortality of morbidity, and prolonged postoperative length of stay (>14 days)
  • Odds ratios were adjusted for all 30 patient risk factors that comprise the STS score
  • After adjustment, off-pump CABG resulted in significantly lower rates of mortality (OR = 0.89, 95% CI 0.84-0.94; p<0.001), stroke (OR = 0.66, 95% CI 0.62-0.71; p<0.001), renal failure (OR = 0.80, 95% CI 0.77-0.84; p<0.001), any mortality of morbidity (OR = 0.78, 95% CI 0.76-0.79; p<0.001) and prolonged length of stay (OR = 0.77, 95% CI 0.74-0.79; p<0.001)
  • Results were not different in a selection of high-volume centers that performed more than 300 off-pump and 300 on-pump procedures during the inclusion period, but the difference between off-pump and on-pump was more pronounced if performed by surgeons with a higher case-load
  • Subgroup analyses according to predicted risk of mortality by STS score showed that there were significant interactions between off-pump CABG and the STS score for all outcomes (p<0.05), where high-risk patients appear to have more benefit from off-pump CABG

My comments

This is an important study to complement the evidence from randomized trials, and is the largest to date to look at the impact of off-pump CABG in a ‘real-world’ setting. It is assuring to see that off-pump CABG could safely be performed in a variety of hospitals with differing experience levels. These findings furthermore add to the recent belief that off-pump CABG may be particularly beneficial to patients at high operative risk.

Nevertheless, inherent to retrospective, observational studies like this one, there is a selection bias as to which patients underwent off- or on-pump CABG. Thorough preoperative patient evaluation is necessary to assess which treatment option may be best for the individual patient, taking into account the STS score but also variables not included in current risk models (e.g. aortic atherosclerosis).

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