Meta-analysis Confirms Mortality Edge with CABG over PCI in Diabetic Patients

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In patients with diabetes and multivessel coronary disease, bypass surgery reduces the incidence of mortality at 5 years by about one-third compared with percutaneous coronary intervention (PCI), regardless of the stent type used, according to a meta-analysis published online September 13, 2013, ahead of print in Lancet Diabetes and Endocrinology.

Researchers led by Subodh Verma, MD, PhD, of St. Michael’s Hospital (Toronto, Canada), conducted a meta-analysis of 8 randomized, controlled trials comparing CABG with PCI in 7,468 patients (3,612 with diabetes). Four of the trials used BMS (ERACI II, ARTS, SoS, and MASS II) and 4 used DES (FREEDOM, SYNTAX, VA CARDS, and CARDia).

Difference Not Evident at 1 Year

Among diabetics, pooled data on 5-year follow-up showed a lower mortality rate for CABG vs. PCI, a difference that was not evident at 1-year follow-up. The mortality benefit of CABG was similar in trials that used either BMS or DES, with no difference between CABG vs. BMS or CABG vs. DES subgroups. There were no differences in nonfatal MI rates between the therapies at either 1-year or 5-year follow-up. Allocation to CABG vs. PCI in was associated with a large reduction in the need for repeat revascularization at mean or median 5 years (or longest) follow-up; this benefit was also apparent at 1-year follow-up. However, CABG imparted a higher rate of nonfatal stroke compared with PCI, particularly at 1-year follow-up (table 1).

Table 1. Outcomes for CABG vs. PCI

 

RR (95% CI)

P Value

All-Cause Mortality
At 1 Year
At 5 Years

0.99 (0.72-1.37)
0.67 (0.52-0.86)

0.97
0.002

Nonfatal MI
At 1 Year
At 5 Years

1.01 (0.54-1.88)
0.76 (0.44-1.29)

0.98
0.30

Repeat Revascularization
At 1 Year
At 5 Years

0.36 (0.22-0.57)
0.41 (0.29-0.59)

< 0.0001
< 0.0001

aNonfatal Stroke
At 1 Year
At 5 Years

2.41 (1.22-4.76)
1.72 (1.18-2.53)

0.01
0.005

a Data available for DES only at 1-year follow-up.

Conversely, there was no difference in mortality with CABG vs. PCI in individuals without diabetes (RR 1.03; 95% CI 0.77-1.37; P = 0.78).

CABG for All?

According to Dr. Verma and colleagues, the results “argue strongly in favor of CABG compared with PCI in patients with diabetes and multivessel disease, and are an important call to action for physicians and patients.”

But in an editorial accompanying the study, Arie Pieter Kappetein, MD, PhD, and Stuart J. Head, MSc, both of Erasmus University Medical Center (Rotterdam, The Netherlands), say the findings do not necessarily translate to a recommendation for CABG in all patients with diabetes, noting that the pathology of CAD in patients with 3-vessel disease is heterogeneous. A patient with occlusion of 2 coronary arteries in combination with a long lesion in a third artery, for example, is more difficult to treat with PCI and has a different prognosis than does a patient with 3 short lesions, they note.

Additionally, they say that Syntax Scores help resolve that shortcoming. But since the meta-analysis did not include such scores, “it cannot be established whether the benefit of CABG compared with PCI is consistent throughout different complexities of coronary artery disease.” Another unresolved issue is whether the advantage of CABG is relevant only to those patients with insulin-dependent diabetes, as suggested by 5-year results from the SYNTAX trial, Drs. Kappetein and Head note.

In an email communication with TCTMD, Eric R. Bates, MD, of the University of Michigan Health System (Ann Arbor, MI), observed that within the limitations of randomized controlled trials that select less than 10% of patients at equipoise for the 2 treatments, CABG has a survival advantage. “However, the clinicians have already selected the high-risk patients for surgery and the low-risk patients for PCI,” he said. “In registries, when clinical decision-making is in play, the mortality results are fairly even, with CABG for complex anatomy and PCI for simple anatomy and patients the surgeons refuse.” Moreover, the enthusiasm for surgery by surgeons needs to be balanced against short-term morbidity, increased stroke risk, and later saphenous vein bypass graft disease, he asserted.

Early Communication Is Key

Dr. Bates added that patient preference also is an important consideration. This thought was echoed by Mark A. Hlatky, MD, of Stanford University School of Medicine (Stanford, CA), whose own meta-analysis of 10 randomized trials comparing CABG with angioplasty or BMS (Hlatky MA. Lancet. 2009;373:1190-1197) found results similar to those of the current study.

“This confirms again that surgery is particularly helpful for people who have diabetes,” he told TCTMD in a telephone interview. “What I think all of this means is that you have to have a conversation with patients . . . and they need to understand their options. There are lots of people who prefer not to have surgery, and that’s understandable, but they need to make an informed decision and to do that they need this kind of information.”

Dr. Hlatky said ad hoc PCI, which is common, often limits the ability to communicate effectively with patients and give them time to make the decision that is best for them. “Obviously you know before that angiogram is done that they have diabetes, so in my opinion this speaks to having those conversations earlier,” he concluded.

Study Details

The mean age of patients was 60 to 65 years. Patients were predominantly men (75%), with several cardiac risk factors or previous MI. Patients with left main disease were excluded or made up a very small proportion of patients, except in the SYNTAX trial, in which 29% had left main disease.

 


Sources:
1. Verma S, Farkouh ME, Yanagawa B, et al. Comparison of coronary artery bypass surgery and percutaneous coronary intervention in patients with diabetes: A meta-analysis of randomized controlled trials. Lancet Diabetes Endocrinol. 2013;Epub ahead of print.

2. Kappetein AP, Head SJ. CABG or PCI for revascularization in patients with diabetes [editorial]? Lancet Diabetes Endocrinol. 2013;Epub ahead of print.

 

 

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Disclosures
  • Drs. Verma, Kappetein, Head, Bates, and Hlatky report no relevant conflicts of interest.

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