CABG ups long-term survival over PCI in diabetes patients with advanced CAD
Coronary revascularization with bypass surgery proves to be superior to drug eluting stents in the long term in preventing all-cause mortality in patients with diabetes mellitus (DM) and multivessel coronary disease (MVD), even 8 years after the procedure, the FREEDOM* Follow-On Study reveals.
In 2012, the FREEDOM trial demonstrated that coronary artery bypass grafting (CABG) led to fewer incidence of all-cause mortality, stroke, and myocardial infarction (MI) compared with percutaneous coronary intervention using drug-eluting stents (PCI-DES) after a median follow-up of 3.8 years.
However, at that point in time, it was uncertain whether the survival benefits with CABG over PCI-DES will persist over the longer term, with concern arising over saphenous graft failure. “For a long-term disease, this is a relatively short-term study, with a median of 3.8 years,” said Prof Valentin Fuster of Mount Sinai Hospital in New York City, New York, US, who presented the study at AHA 2018.
“Follow-up beyond 5 years after coronary revascularization trials is unusual owing to a lack of funding and logistical obstacles,” he stated.
Thus far, not only was the FREEDOM Follow-On Study able to overcome the barriers of a long-term follow-up, it also showed that “CABG remains superior to PCI-DES in reducing all-cause mortality at a follow-up of 8 years.”
Persistent survival benefit
Of the 1,900 patients randomized in the original FREEDOM trial, about half of the participants (n=943, 49.6 percent) continued to participate in the FREEDOM Follow-On Study, forming the “Extended follow-up cohort”. [AHA 2018, abstract LBS.06_18609; J Am Coll Cardiol 2018;doi:10.1016/j.jacc.2018.11.001]
Over a median follow-up of 7.5 years, the rate of all-cause mortality was 23.7 percent among patients treated with PCI-DES compared with 18.7 percent in those receiving CABG (HR, 1.32; p=0.076). Of the 17 centres with data on MI and stroke, incidence was also lower with CABG than PCI for both MI (4.0 percent vs 4.7 percent) and stroke (1.5 percent vs 2.3 percent).
Combining the data from the original FREEDOM trial with median 3.8 years follow-up and the data from the extended follow-up cohort with median 7.5 years follow-up, the difference in all-cause mortality rates between arms became significant in favour of CABG (24.3 percent vs 18.3 percent, hazard ratio [HR], 1.36; p=0.01).
Although the first 2 years of follow-up saw no significant treatment difference between the two procedures (HR, 1.04; p=0.82), PCI led to a significantly higher risk of death than CABG starting from the second year (HR, 1.69; p=0.002).
“The mortality curves [in the original FREEDOM trial] … began to separate during the second year of follow-up. With long-term follow-up, the curves continued to separate, making this difference more pronounced,” Fuster pointed out.
The survival benefit of CABG persisted across most subgroups, including patients with left anterior descending artery involvement, glycated haemoglobin ≥7 percent, and 3-vessel disease. In particular, younger patients (aged ≤63 years) appeared to derive a greater benefit from CABG than PCI-DES (p=0.001), although this requires further confirmation.
“In patients with diabetes and advanced coronary artery disease … CABG was associated with a significant reduction in all-cause mortality at 8 years … even after considering the advances in the PCI technique and improvements in medical therapy,” said Fuster. “These data support current recommendations that CABG be considered the preferred revascularization strategy for such patients.”
“Whether the continual evolution of new DES technology will diminish the advantage of CABG is unclear but appears less likely if the success of CABG is primarily due ot protection of the myocardium against new disease,” said invited discussant Dr Alice Jacobs from the Boston University School of Medicine in Boston, Massachusetts, US.
“The contribution of additional procedures and other adverse outcomes during long-term follow-up, incomplete revascularization, and importantly, newer medications for diabetes that improve cardiovascular outcomes will need to be considered to determine the optimal management of patients with diabetes and multivessel CAD,” she suggested.