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Correspondence  |   October 2005
Underreporting of Conversion from Off-pump Coronary Artery Bypass Surgery
Author Affiliations & Notes
  • Giovanni Landoni, M.D.
    *
  • *Vita-Salute University of Milan, IRCCS San Raffaele Hospital, Milan, Italy.
Article Information
Correspondence
Correspondence   |   October 2005
Underreporting of Conversion from Off-pump Coronary Artery Bypass Surgery
Anesthesiology 10 2005, Vol.103, 902. doi:
Anesthesiology 10 2005, Vol.103, 902. doi:
To the Editor:—
We read with interest the meta-analysis of Cheng et al.  1 recently published in Anesthesiology and agree in considering it the best evidence on which to base future treatment decisions and research directions.2 
With the aim of adding a piece of evidence, we reviewed all of the 37 randomized controlled trials included in the meta-analysis, focusing on the reported incidence of conversion from off-pump (OP) to standard cardiopulmonary bypass (CPB) technique. This is a common event during OP surgery and is caused by either deep intramural vessels (elective) or hemodynamic instability (urgent).
We were surprised to note that only 13 of 37 studies (35.1%) of the meta-analysis stated that they adopted the intention-to-treat analysis, whereas 18 of 37 studies avoided citing this important point, 4 studies affirmed that the patients who crossed over from OP to CPB were excluded from the analysis, and 2 studies considered the converted patients in the CPB group. Only 1 study reported the outcome of the converted patients.
Conversion from OP to standard CPB technique is a common but underreported event, with poor outcome and increased perioperative mortality. An extensive Medline search evidenced only five studies focusing on conversion from OP to CPB, with a cumulative incidence of conversion of 4.85% (202 of 4,163 patients) and a range from 3.7 to 13.3%. Mortality in these patients is 25 in 202 (12.3%). These data are consistent with our experience (Landoni et al.  , unpublished data, Vita-Salute University of Milan, IRCCS San Raffaele Hospital, Milan, Italy, June 2001–July 2003) of a conversion rate of 37 in 450 (8.2%), with 2 in 37 deaths (5.4%).
We suggest that conversion from OP to standard CPB is underreported in literature and recommend that outcome of converted patients should be reported in future randomized controlled studies.
*Vita-Salute University of Milan, IRCCS San Raffaele Hospital, Milan, Italy.
References
Cheng DC, Bainbridge D, Martin JE, Novick RJ: Evidence-based Perioperative Clinical Outcomes Research Group. Does off-pump coronary artery bypass reduce mortality, morbidity, and resource utilization when compared with conventional coronary artery bypass? A meta-analysis of randomized trials. Anesthesiology 2005; 102:188–203Cheng, DC Bainbridge, D Martin, JE Novick, RJ
Floyd T, Fleisher LA: Off-pump coronary artery bypass and the hypothesis from which it grew: Is it yet to be tested? What are the downsides of the lingering questions? Anesthesiology 2005; 102:3–5Floyd, T Fleisher, LA