Patients with type 2 diabetes and stable coronary artery disease (CAD) had better outcomes when optimal medical therapy was accompanied by coronary artery bypass grafting (CABG), according to a meta-analysis.
Combined death, myocardial infarction, and stroke rates over a median of 4.5 years favored a strategy of optimal medical therapy with CABG in lieu of a PCI-medication combination on multivariable adjustment (HR 0.71, 9% CI 0.59-0.85). With the CABG-medication route, reduced were death (HR 0.76, 95% CI 0.60-0.96) and myocardial infarction (MI; HR 0.50, 95% CI 0.38-0.67) — but not stroke (HR 1.50, 95% CI 0.93-2.42), reported G.B. John Mancini, MD, of University of British Columbia in Vancouver, and colleagues.
Their study, published online in the Journal of the American College of Cardiology, also showed that the addition of CABG to optimal medical therapy was linked to an improvement for the combined endpoint (HR 0.81, 95% CI 0.66-1.00) and myocardial infarction (HR 0.56, 95% CI 0.41-0.75).
On the other hand, PCI did not boost any outcomes with optimal medical therapy, irrespective of left ventricular ejection fraction (LVEF), number of diseased vessels, or proximal left anterior descending artery (pLAD) involvement.
Calling a CABG-optimal medical therapy combination the “preferred management strategy” for patients with type 2 diabetes and stable CAD, the authors suggested that they “provide strong evidence to support optimal medical therapy alone as the next best therapeutic approach.”
If that still doesn’t work to control angina or improve quality of life, they concluded, PCI plus medication may then be an “appropriate therapeutic option.”
“CABG targets angiographically significant lesions, but provides protection from less significant lesions as well (in the bypassed segment), whereas PCI targets angiographically significant lesions alone, which may explain some of the superior cardioprotection (for the outcome of MI) offered by CABG over PCI,” suggested Sripal Bangalore, MD, MHA, of New York University School of Medicine.
“CABG will be hard to beat because of the superior protection against future events in the bypassed segment,” he wrote in an accompanying editorial.
“However, the mortality gap between PCI and CABG can be lowered by using newer-generation DES to reduce ‘stent-related’ events and aggressive optimal medical therapy to reduce ‘non–stent-related’ events.”
Mancini’s team pooled data from three trials (n=5,034): BARI 2D, COURAGE, and FREEDOM. Among the enrollees, 77% had multivessel CAD.
The group acknowledged that the study had fairly low numbers of patients with low LVEF (15%) or pLAD involvement in their disease (28%). Furthermore, all three trials excluded patients with left main CAD.
“We did not undertake a comparison of patients with or without complete revascularization, nor were measures of fractional flow reserve or quantitation of induced ischemia available in all patients,” Mancini and colleagues added.
Bangalore posed the question: “Should the guidelines be changed to favor CABG + optimal medical therapy in patients with diabetes given the reduction in major cardiovascular events and MI in this analysis over optimal medical therapy alone?”
“Perhaps not,” he wrote, citing newer alternatives in optimal medical therapy such as proprotein convertase subtilisin/kexin type 9 inhibitors, sodium glucose transporter-2 inhibitors, and glucagon-like peptide-1 receptor agonists.
“Critics would argue that the practice of PCI and CABG has advanced considerably, and so has the choice of optimal medical therapy.” Medication also has the edge of being the only therapy shown to target both angiographically significant and less significant lesions, the editorialist noted.
“However, there is no clear consensus as to what constitutes optimal medical therapy, and there is controversy over whether all components of optimal medical therapy (especially beta-blockers) reduce death or MI in patients with stable CAD without prior MI.”
“Moreover, medication therapy is associated with adverse side effects, the individual response to therapy is variable, and the compliance rates are low. Thus, even in randomized trials, the achievement of optimal medical therapy has been poor,” according to Bangalore.
Mancini disclosed receiving honoraria from Regeneron, Merck Canada, Amgen, Sanofi, Boehringer Ingelheim, and AstraZeneca; and serving on advisory boards for Amgen and Sanofi.
Bangalore reported grant support from the NIH for the ISCHEMIA and the ISCHEMIA-CKD trials. His editorial referred to work supported by National Heart, Lung, and Blood Institute grants U01HL105907 and U01HL117905; in-kind donations from Abbott Vascular, Medtronic, St. Jude Medical, Volcano Corporation, Arbor Pharmaceuticals, AstraZeneca, Merck Sharp & Dohme, and Omron Healthcare; and by financial donations from Arbor Pharmaceuticals and AstraZeneca.
Journal of the American College of Cardiology
Mancini GBJ, et al "Medical treatment and revascularization options in patients with type 2 diabetes and coronary disease" J Am Coll Cardiol 2016; DOI: 10.1016/j.jacc.2016.06.021.
Journal of the American College of Cardiology
Bangalore S "Applicability of the COURAGE, BARI 2D, and FREEDOM trials to contemporary practice" J Am Coll Cardiol 2016; DOI: 10.1016/j.jacc.2016.020.