Survival of patients on dialysis having off-pump versus on-pump coronary artery bypass surgery in the United States

Abstract

Background: Patients on dialysis sustain at least a threefold higher in-hospital mortality rate and markedly higher long-term mortality following coronary artery bypass graft surgery than the general population. Smaller studies have suggested that dialysis patients have superior outcomes with off-pump compared with on-pump coronary artery bypass surgery.

Methods: From the United States Renal Data System database, 13,085 patients on dialysis having first coronary artery bypass surgery between 2001 and 2006 were identified. Of these, 2335 (17.8%) had off-pump coronary artery bypass surgery. The Kaplan-Meier method was used to estimate survival of patients having off-pump coronary artery bypass and patients having on-pump coronary artery bypass. A Cox proportional hazards model was used to assess effects of off-pump coronary artery bypass on mortality with adjustment for baseline patient characteristics.

Results: Off-pump coronary artery bypass surgery was associated with significantly reduced all-cause mortality compared with on-pump coronary artery bypass surgery (hazard ratio 0.92, 95% confidence interval 0.86-0.99, P = .02). The observed survival benefit was most notable in the first year after surgery (70.3% vs 68.7%) and was lost 2 years after surgery (55.4% vs 55.2%). No difference was noted in the in-hospital mortality rate with off-pump coronary artery bypass surgery versus on-pump coronary artery bypass surgery (9.7% vs 11.0%, P = .06). Cardiac mortality during the follow-up period was similar (23.6% vs 23.8%; adjusted hazard ratio 0.95, 95% confidence interval 0.86-1.04, P = .26). Use of internal thoracic grafts was independently associated with improved survival after coronary artery bypass surgery (hazard ratio, 0.92; 95% confidence interval, 0.87-0.98, P = .0057).

Conclusions: Patients on dialysis sustain high in-hospital and 2-year mortality rates after coronary artery bypass surgery. Off-pump coronary artery bypass is associated with modestly increased survival compared with on-pump coronary artery bypass, a benefit most marked early after off-pump coronary artery bypass.