“Real-world” patients with 3-vessel or left main disease who undergo CABG experience less cardiac death, MI, and revascularization after 5 years than those who receive PCI, regardless of diabetes status, according to a multicenter registry study published online February 2, 2015, ahead of print in the American Journal of Cardiology.

For the analysis, Akira Marui, MD, PhD, of the Kyoto University Graduate School of Medicine (Kyoto, Japan), and colleagues looked at 3,982 patients with 3-vessel or left main disease who received PCI or CABG at 26 Japanese centers from January 2005 through December 2007 and were enrolled in the CREDO-Kyoto PCI/CABG registry Cohort 2. 

Outcomes were analyzed according to diabetes status. In the diabetic cohort, 1,065 patients underwent PCI and 933 surgery; among nondiabetics, 1,123 received PCI and 861 CABG. Most PCI patients received DES (70% of diabetics and 76% of nondiabetics).

Differences in baseline clinical and angiographic characteristics between the PCI and CABG groups were consistent regardless of diabetes status. However, diabetic patients who underwent PCI had higher hemoglobin A1c levels than those who received CABG. In addition, Syntax scores were higher in diabetics than nondiabetics.

CABG Improves Long-term Outcomes

At 30 days postprocedure, unadjusted rates of mortality and MI were similar between the PCI and CABG cohorts for both diabetic and nondiabetic patients. Stroke rates, however, were higher with CABG than PCI for nondiabetic patients (P = .01). 

After propensity-score adjustment, 5-year mortality was higher after PCI than CABG in diabetic but not in nondiabetic patients. Rates of cardiac death were higher after PCI in both nondiabetics and diabetics, although the difference reached only borderline significance in the latter group. Compared with CABG, both MI and any coronary revascularization occurred more often in the PCI group regardless of diabetes status (table 1).

There was, however, no significant interaction between diabetes status and the effect of PCI relative to CABG for any of the outcomes.

Even after results from the ASCERT, SYNTAX, and FREEDOM trials, the authors say, “it is still unclear whether the survival benefit of CABG over PCI is [different for] diabetic and nondiabetic patients.” In particular, “[i]nclusion of 3-vessel and left main disease in the current study as well as the SYNTAX trial might have diluted the difference in outcome between diabetic and nondiabetic patients,” they explain. 

Optimal Treatment Remains Unclear

In an email with TCTMD, Steven Marso, MD, of the University of Texas Southwestern Medical Center (Dallas, TX), said that he did not necessarily agree with the authors’ conclusion that “’[t]here was no difference in the direction and magnitude of treatment effect of CABG relative to PCI regardless of diabetic status.’ In fact, I think there were notable differences between the outcomes of patients with and without diabetes in this nonrandomized comparison,” he said. “After adjusting for measured confounders… the difference in mortality in [the] nondiabetic cohort was no longer apparent.”

Nonetheless, Dr. Marso commented, “[i]n the appropriate population—ie, [those with] multivessel disease and a high Syntax score—[CABG] is likely preferable to multivessel PCI. Whether or not this is true for lower-risk diabetic patients is unclear from the current literature.”

Dr. Marso also highlighted the “somewhat surprising” finding that nonfatal MI occurred more frequently after PCI than CABG in the nondiabetic cohort.

He agreed with the authors that there might have been differences in outcomes if left main disease had been separated from 3-vessel disease in the analysis. “In fact,” Dr. Marso continued, “SYNTAX suggested that PCI is comparable to bypass surgery in patients with isolated left main disease.”

He called for more “meaningful clinical studies to elucidate the optimal treatment strategy for this very high-risk cohort of people.”

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Source:
Marui A, Kimura T, Nishiwaki N, et al. Five-year outcomes of percutaneous versus surgical coronary revascularization in patients with diabetes mellitus (from the CREDO-Kyoto PCI/CABG registry Cohort-2). Am J Cardiol. 2015;Epub ahead of print.

Disclosures:

• The study was supported by the Pharmaceuticals and Medical Devices Agency of Japan.
• The paper contains no statement regarding conflicts of interest for Dr. Marui.
• Dr. Marso reports no relevant conflicts of interest.

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