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

Abstract

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. 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. 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). 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.