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Off-pump CABG shows early mortality and morbidity advantages compared with on-pump, especially for women, but equivalent long-term survival, study suggests

Thursday, October 16 2008 | Comments
Evidence Grade 3 What's This?
A large retrospective study of coronary artery bypass grafting (CABG) both with and without (off-pump) cardiopulmonary bypass (CPB) suggests that off-pump CABG reduces perioperative morbidity and mortality, especially for females, but that long-term survival is equivalent.

Medical records were reviewed for 12,812 consecutive patients who had off-pump CABG (n=5,667) or CABG with CPB (n=7,145) at Emory University in Atlanta between 1997 and 2006. Scheduled, urgent, and emergent operations were included in the study.

CABG on CPB was performed using standard techniques. Off-pump CABG was performed using one of several commercially available cardiac positioning and coronary artery stabilizing devices.

The study was conducted to compare in-hospital major adverse cardiac events (MACE) in men and women and to determine whether gender or type of surgery (or their interaction), affect long-term survival up to 10 years after CABG.

In the CPB arm, there were 1,924 females and 5,221 males, with a mean patient age of 64.8 and 61.6 years, respectively. In the off-pump arm, there were 1,786 females and 3,881 males, with a mean patient age of 65.0 and 62.1 years, respectively.

In both arms, the female patients were older than their male counterparts (64.9 vs 61.8 years, P<.001) and their predicted risk of mortality as determined by the Society of Thoracic Surgeons (STS) was also higher (0.032 vs 0.018, P<.001).  In general, the female patients had more comorbidities than the males.

A comparison of patient demographics between the off-pump and CPB groups demonstrated similar results: female off-pump CABG patients were older than their CPB counterparts (63.0 vs 62.4 years, P=.003), had a higher STS predicted risk of mortality (0.023 vs 0.021, P=.001), and more comorbidities. In addition, women treated with off-pump CABG had a higher STS risk of mortality when compared with women treated with CABG on CPB (0.033 vs 0.030, P=.021).

In the entire cohort, the unadjusted rates of death, stroke, and MACE were significantly higher for women than for men in the 30-day perioperative period (P<.001 for each). Similarly, when compared with CPB patients, off-pump patients had significantly lower rates of death, stroke, and overall MACE (P<.001 for each).

When the outcomes were adjusted for risk, off-pump patients had lower rates of death (P=.045), stroke (P<.001), and overall MACE (P=.018). The rates of MI were not significantly different (P=.15). Female gender was also associated with higher rates of death, stroke, and overall MACE (P<.001 for each) as compared with male gender.

During the study period, 2,308 of the 12,812 patients (18%) died. Analysis showed that female CPB patients were significantly more likely to die than female off-pump patients (P=.005), but the same relationship was not seen in male CPB versus off-pump patients (P=.51). After the cohort was adjusted for propensity score and age, female gender continued to have a higher risk of death versus male gender (P=.011), but there was no correlation between female gender and type of surgery (P=.49).

These results indicated that there was a higher risk of death, stroke, MI, and the composite endpoint of death/stroke/MI in CAMG for women when compared with men, the researchers noted. Although off-pump CABG had superior risk-adjusted outcomes for both men and women, the authors concluded that women may benefit more than men by avoiding CABG on CPB.

Ultimately, the results demonstrated that women had poorer long-term survival after CABG as compared with men, regardless of surgery type, but when the cohort was combined, both types of surgery had similar rates of long-term survival. (Puskas JD et al. Ann Thorac Surg 2008; 86:1139-1146.)

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