On-pump CABG superior to off-pump at 5 years
Individuals who underwent coronary-artery bypass grafting (CABG) with cardiopulmonary bypass (on-pump) had better survival and cardiovascular outcomes compared with those whose CABG procedure was done without cardiopulmonary bypass (off-pump), according to a follow-up of the ROOBY* trial.
At 5 years, death rate was higher among patients who underwent off-pump CABG compared with those who underwent on-pump CABG (15.2 percent vs 11.9 percent; relative risk [RR], 1.28, 95 percent confidence interval [CI], 1.03–1.58; p=0.02), as was the rate of major adverse cardiovascular events (MACE) which was a composite of death from any cause, repeat revascularization either via CABG or percutaneous coronary intervention (PCI), or nonfatal myocardial infarction (MI; 31.0 percent vs 27.1 percent; RR, 1.14, 95 percent CI, 1.00–1.30; p=0.046). [N Engl J Med 2017;377:623-632]
There were no significant differences between off- and on-pump CABG in terms of nonfatal MI (12.1 percent vs 9.6 percent; RR, 1.27; p=0.05), death from cardiac causes (6.3 percent vs 5.3 percent; RR, 1.20; p=0.29), repeat revascularization (13.1 percent vs 11.9 percent; RR, 1.10; p=0.39), repeat CABG (1.4 percent vs 0.5 percent; RR, 3.19; p=0.02), or PCI (11.9 percent vs 11.6 percent; RR, 1.03; p=0.82) at 5-years after the initial procedure.
Following exclusion of patients who converted procedures (on-pump to off-pump and vice versa), death rate and composite MACE incidence at 5 years were comparable between patients in the off- vs on-pump groups (13.5 percent vs 11.0 percent; p=0.09 and 29.1 percent vs 26.5 percent; p=0.21 for death rate and MACE, respectively).
“[T]he 5-year outcomes in our study support the conclusion that off-pump CABG does not offer any substantial advantages over on-pump CABG except possibly in unusual situations,” said the researchers, citing “patients with an extensively calcified (porcelain) aorta” as an example of those who may benefit from the off-pump procedure.
“Given the results, it appears that innovative surgical approaches – such as the more technically demanding off-pump procedure – may not always provide superior clinical outcomes,” they said.
This analysis was carried out on 2,203 patients (mean age 62.7 years, 99.4 percent male) from 18 Veterans Affairs medical centres in the US who were randomized to undergo on-pump (n=1,099) or off-pump (n=1,104) CABG between February 2002 and June 2007. There were 299 deaths over the 5-year follow-up period.
“[M]ultiple studies have shown that off-pump CABG results in less complete revascularization and worse graft patency than the on-pump approach,” said the researchers, who pointed to this factor as a potential reason for the reduction in off-pump CABG in the US over the years. [Cochrane Database Syst Rev 2012;doi:10.1002/14651858.CD007224.pub2; N Engl J Med 2004;350:21-28; J Thorac Cardiovasc Surg 2014;148:1812-1819]
“Less complete revascularization is known to decrease long-term survival, and this may be a mechanism for the shorter survival that has been observed among patients who have undergone an off-pump procedure,” they said.
“These observations suggest that the worse outcomes associated with the less-effective revascularization of off-pump CABG are not confined to the early postoperative period but have long-lasting negative consequences,” said Drs Eugene Blackstone and Joseph Sabik III from the Cleveland Clinic and Cleveland Medical Center in Ohio, US, respectively, in an editorial. [N Engl J Med 2017;377:692-693]
The researchers cautioned that the findings may not extend to the entire population, seeing as the study population consisted primarily of male veterans with multiple comorbidities, and recommended a 10-year post-CABG follow-up study as well as studies to identify the factors that would affect the outcomes.