Author + information
- Kan Kajimoto, MD, PhD∗ (, )
- Taira Yamamoto, MD and
- Atsushi Amano, MD
- ↵∗Department of Cardiovascular Surgery, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan
We read with interest the report by Kim et al. (1) indicating that post-operative survival was lower in patients who underwent off-pump coronary artery bypass grafting (CABG) than on-pump CABG. However, several crucial limitations to the study are notable and cast doubt on their conclusion that off-pump CABG results in poorer long-term survival.
One limitation is the considerable difference in the number of distal anastomoses between the 2 groups. The mean number of distal anastomoses was 3.0 for off-pump CABG and 3.7 for on-pump CABG. It appears that the investigators may have demonstrated the weakness of incomplete revascularization rather than that of off-pump CABG. Furthermore, this discrepancy raises a potential problem when attempting to compare long-term survival between the 2 groups. If complete revascularization were achieved in both the on-pump and off-pump groups, the difference in the number of distal anastomoses would reflect differences in the pre-operative severity of the coronary artery lesions. As a result, regardless of whether propensity-matched analysis was conducted, there would be a disparity in the characteristics of the groups that would markedly affect the results.
The next limitation is the quality of the off-pump CABG performed in the present study. Off-pump CABG produces outcomes that are comparable or superior to those of conventional CABG in Japan (2–4). Off-pump CABG should only be selected when revascularization is judged to be equivalent to that achievable with on-pump CABG. Despite this caveat, more than 60% of CABG procedures performed in Japan since early 2000 have been off-pump, and no declines in treatment outcomes have been observed. This shows that Japanese surgeons have become proficient in off-pump CABG techniques in the past dozen years. Conversely, as shown in the present study, off-pump CABG has only recently become widely used in South Korea; it was not until 2006 that a majority of CABG procedures were performed off-pump. Thus, off-pump CABG has not yet been standardized, and the present study was conducted while South Korean surgeons were still acquiring the required techniques. Under these conditions, it is premature to compare the relative merits of on-pump and off-pump CABG in a South Korean cohort, and the findings of the present study are ultimately inconclusive. We look forward to further research findings once off-pump CABG has become established in South Korea.
- American College of Cardiology Foundation
- Kim J.B.,
- Yun S.C.,
- Lim J.W.,
- et al.
- ↵Sezai Y, Japanese Association for Coronary Artery Surgery. Results of nationwide questionnaire of coronary artery surgery 2011 [in Japanese]. Available at: http://www.jacas.org/enquete/slide_2011.pdf. Accessed May 13, 2014.