CABG Preferable to PCI for Multivessel Disease in Diabetics: Canadian Registry

Veronica Hackethal, MD

November 13, 2015

ORLANDO, FL — Diabetic patients undergoing revascularization for multivessel coronary disease have a lower risk of death, heart attack, and serious complications if they receive CABG instead of PCI, especially if the setting is stabilized acute coronary syndrome, suggests Canadian registry data presented this week here at the American Heart Association (AHA) 2015 Scientific Sessions[1].

"Our data suggest that some people undergoing PCI may be better with bypass surgery. However, we need a proper randomized controlled trial to answer this question," commented lead author Dr Krishnan Ramanathan (University of British Columbia, Vancouver).

The results provide real-world confirmation of findings from the FREEDOM trial, which showed superiority of bypass surgery over PCI with drug-eluting stents (DES) in diabetics with multivessel disease.

But they also challenge perceptions that FREEDOM and similarly themed SYNTAX and BARI-2D would have yielded different results if they had been performed with newer-generation DES, especially everolimus-eluting stents.

Impact of Stent Choice

The current study took place during the time period when mostly second-generation DES were being used in Canada, but Ramanathan believes that using newer stents would not have affected the results much.

"Given the magnitude of difference we've shown [in our trial] and also in FREEDOM, it's unlikely that third-generation DES [would] significantly change the study findings, as even the newer generation of DES do not affect the underlying atherosclerotic process," he said.

One reason CABG might be preferable to PCI for some diabetic patients is that PCI tends to treat a focal segment of the disease, Ramanathan explained. In diabetics, the disease often involves the entire segment of the coronary arteries. So CABG protects against any other problems that could crop up in other parts of the vessel.

Number of PCIs in Diabetics Increasing Over Time

Currently, patients with diabetes and multivessel disease are being evaluated as to whether or not they are suitable just for PCI, according to Dr. Ramanathan,

The National Cardiovascular Disease Registry (NCDR) shows that the most common revascularization strategy in a diabetic with non-ST-segment-elevation MI (NSTEMI) and multivessel coronary artery disease is PCI, and the number of PCIs is increasing over time, he pointed out.

Results from this study, though, suggest that these patients should be evaluated for their suitability for bypass surgery, in addition to PCI.

"At the time of angiography, it will require not just selecting people for PCI but having a conversation to decide what is the optimal revascularization strategy," he said, "At the present time, patients are largely treated with PCI and not going on to subsequent bypass surgery because they're put on antiplatelet therapy and other things."

In the current study, researchers linked provincewide registries to identify diabetic patients with multivessel coronary artery disease (CAD), regardless of renal or cardiac function, who received revascularization between 2007 and 2014.

They used ICD-10 codes to identify stroke and MI and a vital statistics database to identify death. Then they looked at major cardiac/cerebrovascular events (MACCE) using a composite scores of death, nonfatal MI, and nonfatal stroke and adjusted analyses for baseline risk factors.

The analysis included 4937 procedures, 60% of which were PCI. Patients who received PCI were older and more likely to be female and had higher rates of pulmonary and liver disease (P<0.001). Patients who received CABG had higher rates of disease in the proximal left anterior artery (P<0.001).

Sixty-three percent of patients underwent revascularization for ACS. Of the patients who received PCI, 68% had ACS as the indication; the proportion was 54% among those who underwent CABG (P<0.001). Fifty-nine percent of CABG patients and 70% of PCI patients had emergent or urgent procedures (P<0.001).

Short-term outcomes (30 days to 12 months) favored CABG for the composite end points death and MI, but not for stroke. Long-term outcomes (31 days to 5 years) favored CABG for all end points.

Up to 30 days after the procedure, ACS patients showed significantly greater benefit for CABG compared with PCI (P interaction= 0.005). Thirty or more days postprocedure, the benefit of CABG over PCI was not significantly different for ACS compared with non-ACS patients (P interaction= 0.791)

Rethinking the Paradigm

According to Ramanathan, the next step is that diabetic patients with multivessel disease will need closer examination to determine optimal treatment strategy after ACS.

Data from the study suggest that factors that predict acuity of a patient are used to select patients for PCI, while factors that predict anatomical severity are used to select patients for bypass surgery, he explained.

But "maybe we need to rethink that paradigm. Rather than just using the clinical and anatomical criteria, we may need to think about the diabetic patient as being more than that," he concluded, "These patients should be considered and given the opportunity to have bypass surgery rather than simply proceeding with ad hoc PCIs."

The authors report no relevant financial relationships.

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