CABG Improves Late Survival, Stroke vs PCI in Patients With Diabetes, Poor LV Function

Marlene Busko

April 05, 2018

Long-term mortality and rates of cardiovascular events and stroke were significantly lower after coronary bypass (CABG) surgery than after percutaneous coronary intervention (PCI) in patients with type 2 diabetes and left ventricular (LV) systolic dysfunction, in a cohort study.

"Given a paucity of published data in the patient population that are what I would call double jeopardy — with both diabetes and left ventricular dysfunction — we sought to do the strongest-level observational study that we can in the absence of a clinical trial," which is a propensity-matched study, Jayan Nagendran, MD, PhD, University of Alberta, Edmonton, Canada, told theheart.org | Medscape Cardiology.

Our analysis shows "what we as surgeons have suspected, that patients with left ventricular dysfunction and diabetes have very acceptable outcomes with bypass surgery," he said.

"The other very important highlight is, the incidence of stroke was not significantly different with the two strategies."

Therefore, conclude the authors, "Apart from those patients who have prohibitive surgical risk or technical factors limiting surgical revascularization, CABG should be considered first-line therapy for the treatment of multivessel CAD" in patients with diabetes and LV dysfunction.

The study, based on data from the Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease (APPROACH), was published online February 27 in the Journal of the American College of Cardiology with Jayan Nagendran as senior author and Jeevan Nagendran, MD, PhD, University of Alberta, as lead author.

These findings are "welcome and important" since "remarkably" there have been no randomized, controlled trials or even adequately powered subgroup analyses comparing CABG vs PCI in this specific population, notes an accompanying editorial by Eric J Velazquez, MD, Duke University, Durham, North Carolina, and Mark C Petrie, MBChB, University of Glasgow, United Kingdom.

The study also "highlights the fact that everybody who has a low ejection fraction and heart failure probably needs to be evaluated for the extent of coronary disease," Velazquez told theheart.org | Medscape Cardiology. "We don't know how many patients with diabetes and low ejection fraction were actually never referred for angiography."

Diabetes, Low LVEF Underrepresented in Trials

Patients with diabetes and LV systolic dysfunction that is either moderate, defined by an LV ejection fraction (LVEF) of 35% to 49%, or severe, with an LVEF less than 35%, represent a growing clinical challenge, note Nagendran and colleagues.

But clinical trials that have compared the two forms of coronary revascularization have tended not to include many patients with both low LVEF and diabetes. 

For example, the Future Revascularization in Patients With Diabetes Mellitus: Optimal Management of Multivessel Disease (FREEDOM) trial compared CABG and PCI in patients with coronary artery disease (CAD) and diabetes, but only 3% of patients had a low LVEF, the group notes.

Also, the Surgical Treatment for Ischemic Heart Failure—Extension Study (STICHES) trial compared CABG vs medical therapy in patients with low LVEF, but less than 40% of participants had diabetes.

Indeed, because of the generally narrow entry criteria of clinical trials, patients enrolled in them typically make up less than 20% of those getting coronary revascularization in clinical practice, said Jayan Nagendran.

The APPROACH Cohort

The researchers identified 110,655 patients in the APPROACH database who underwent coronary angiography for suspected CAD for the first time in the province of Alberta from 2004 to 2016.

They excluded 71,826 patients who did not have multivessel CAD, more than 26,344 who did not have diabetes, 3038 who went on to medical treatment only, and 6610 who had LVEF greater than 50%.

Of the remaining 2837 patients, 1556 went from angiography to PCI and 1281 underwent isolated CABG. Their mean age was 65 years, and 23% were women.

Within that cohort, 869 patients who went to PCI were propensity-matched to 869 patients who underwent CABG. Of those 1738 patients, 973 (56%) had moderate LV dysfunction and 765 (44%) had severe LV dysfunction.

Better Late Outcomes With CABG

At 5 years, patients who had PCI showed a higher incidence of the primary outcome of major adverse cardiac and cerebrovascular events (MACCE), defined as death, stroke, myocardial infarction, or repeat revascularization.

That was also true within the patient subgroups with moderate and severe LV dysfunction (P < .001 for the comparisons overall and within both patient subgroups).

Table. Hazard Ratios for Outcomes: Propensity-Matched PCI vs CABG Cohortsa

Outcome per EF HR (95% CI) P Value
EF 35% - 49%    
  MACCE 1.97 (1.64 - 2.35) <.001
  Death 1.34 (1.07 - 1.68) .01
  Repeat revascularization 5.46 (3.80 - 7.78) <.001
EF < 35%    
  MACCE 2.28 (1.79 - 2.90) <.001
  Death 1.62 (1.20 - 2.22) .002
  Repeat revascularization 7.31 (4.08 - 13.10) <.001
aAt 50 months for MACCE and at 62 or 63 months for the other outcomes.

CI = confidence interval; EF = ejection fraction; HR = hazard ratio

 

The rate of stroke at 5 years was similar after PCI or CABG in patients with moderate or severe LV dysfunction (4% vs 3% for subgroups; P > .60).

The current findings, according to the editorialists, "should put the cardiovascular community on high alert and spur important next steps."

And, Velazquez said in an interview, "I believe the next step for dissemination and moving forward always has to have a randomized trial as part of it."

With APPROACH, that next step could be to develop a randomized trial within the data set, to randomly assign its patients to treatment and then follow outcomes by using the existing infrastructure. "That to me is the future," he said.

"Until then, these findings in support of CABG should be carefully integrated into discussions with diabetic patients with LV systolic dysfunction who are facing revascularization," the editorialists conclude.

Jeevan Nagendran, Jayan Nagendran, and their coauthors report they have no relevant financial disclosures. Velazquez reports receiving research grants from the National Heart, Lung, and Blood Institute, Alnylam, Amgen, Novartis, and Pfizer; providing consulting services for Abiomed, Amgen, Merck, Novartis, Pfizer, and Philips Ultrasound; and receiving speakers honoraria from Expert Exchange. Petrie reports receiving speakers fees, research grants, or consulting honoraria from Takeda, Novartis, AstraZeneca, Maquet, Boehringer Ingelheim, Pfizer, Daiichi-Sankyo, Servier, Eli Lilly, and Novo Nordisk; and serving on clinical-events committees for Roche, Bayer, Stealth Biotherapeutics, AstraZeneca, GlaxoSmithKline, Astellas, Cardiorentis, Reservlogix, and Boehringer Ingelheim.

J Am Coll Cardiol.  Published online March 26, 2018. Abstract, Editorial

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