Off-pump vs. on-pump CABG: Does it really matter?

Five-year survival rates and cardiovascular outcomes are similar between elderly patients who undergo both off- and on-pump coronary artery bypass grafting (CABG), according to research out of Germany.

The study, published in Circulation Feb. 8, confirmed the results of three large-scale trials that enrolled a cumulative 10,000 CABG patients, first author Anno Diegeler, MD, PhD, and colleagues wrote. Those studies and others suggested outcomes after off- and on-pump CABG were similar up to a year after surgery, but emergent research has reported conflicting long-term results.

“A consistent feature of all three trials was that patients who were operated off-pump received fewer grafts than the respective on-pump cohort,” Diegeler and co-authors wrote. “In the German Off-Pump CABG in Elderly Patients (GOPCABE) trial, a higher number of patients in the off-pump group received fewer coronary grafts than initially planned. This raises questions about the clinical long-term efficacy and durability of off-pump CABG.”

Thirty-day and one-year data from the GOPCABE study revealed no significant differences in rates of death, stroke, MI, new renal replacement therapy or repeat revascularization between off- and on-pump patients. Diegeler et al. took on the study’s five-year results, looking at outcomes among 2,539 patients randomized to off-pump or on-pump CABG at 12 German centers between 2008 and 2011.

After five years, the authors said 31 percent of patients assigned to off-pump CABG had died, and 30 percent of patients assigned to on-pump CABG had died. The secondary composite outcome of death, MI and repeat revascularization occurred in 34 percent of patients after off-pump procedures and 33 percent after on-pump surgeries.

The data also stated that incomplete revascularization occurred in 34 percent of patients randomized to off-pump and 29 percent of patients randomized to on-pump CABG. Five-year survival rates were 72 percent and 76 percent for off-pump patients with incomplete versus complete revascularization, respectively, and 72 percent and 77 percent for on-pump patients with incomplete versus complete revascularization, respectively.

Incomplete revascularization was the only clear predictor of a poorer outcome, and pointed to reduced late survival in CABG patients. The authors said both subgroups of patients with incomplete revascularization showed significant differences in baseline characteristics—so different they said incomplete revascularization characterized an entirely different patient group of sicker individuals.

“All efforts to adjust for these differences with multivariate regression are limited, and no propensity matching would be able to eliminate the bias of additional confounders when one patient group is obviously sicker than the other,” Diegeler and co-authors wrote. “Accordingly, the inability to achieve a complete revascularization may be considered as the manifestation rather than the cause of a worse patient prognosis.

“However, given the worse prognosis that was observed, every effort should be undertaken to achieve a complete revascularization whenever possible.”