Stroke-Reduction Benefit With Off-Pump CABG: Meta-Analysis

August 26, 2015

BYDGOSZCZ, POLAND — A large meta-analysis focusing on short-term outcomes finds support for off-pump CABG surgery, with investigators reporting no differences in the rate of MI and all-cause mortality between off-pump surgery and CABG with cardiopulmonary bypass (CPB) but documenting a reduction in stroke with the off-pump procedure[1].

Surgery performed off-pump was associated with a 28% relative reduction in the risk of stroke at 30 days.

The researchers, led by Dr Mariusz Kowalewski (Nicolaus Copernicus University, Bydgoszcz, Poland), say they also observed a "significant linear relationship" between the patient's baseline risk profile and the benefits of off-pump CABG for all clinical end points. Individuals at the highest risk for surgery, such as older patients, those with diabetes, renal failure, or those with chronic pulmonary disease, among other risk factors, fared significantly better with off-pump CABG compared with those treated with conventional surgery.

"Why high-risk patients are less likely to develop complications after [off-pump CABG] than their conventional CABG counterparts remains a subject of ongoing debate," write Kowalewski and colleagues in their report, published online August 14, 2015 in the Journal of Thoracic and Cardiovascular Surgery. "The use of CPB has been associated with a systemic inflammatory response affecting multiple organ systems, such as the brain, heart, lungs, kidney, and the gastrointestinal tract. Avoidance of CPB and, in turn, interactions between the inflammatory, coagulation, and fibrinolytic cascades confer complex, organ-specific benefits, especially in high-risk patients."

The meta-analysis included 19,192 patients, with 36 studies that examined all-cause mortality and 43 studies with MI as an end point. Among the data were studies such as the CORONARY trial, a randomized trial comparing off-pump and on-pump CABG in 4752 individuals, and the ROOBY trial, another head-to-head comparison with more than 2200 individuals treated at Veterans Affairs' hospitals.

For all-cause mortality at 30 days, the rates were 2.04% in the off-pump-CABG arm and 2.45% in the CABG-with-CPB arm, respectively. This difference was not statistically significant. For MI, the rates ranged from 4.31% for patients treated off-pump to 4.67% for those receiving CPB. Again, the difference was not statistically significant. When patients were stratified by risk profile, the researchers observed a significant relationship between the benefit of off-pump CABG surgery among higher-risk patients with respect to all-cause mortality, MI, and stroke.

"The findings on mortality benefit with [off-pump CABG] in high-risk patients corroborate on a larger scale the hypothesis that beyond a certain patient's risk threshold, off-pump CABG performs better than CABG," write Kowalewski and colleagues.

Compared with MI and all-cause mortality, there was a benefit to off-pump CABG surgery with respect to stroke in the overall analysis, a benefit that wasn't observed in CORONARY and ROOBY. In the meta-analysis, the overall incidence of stroke in 40 studies was 1.67%, with a rate of 1.34% in the off-pump CABG arm and 2.0% in the CABG-with-CPB group (odds ratio 0.72; 95% CI 0.56–0.92).

Currently, the European Society of Cardiology guidelines on myocardial revascularization state that off-pump CABG surgery is relegated to high-risk patients and should be performed at high-volume centers (class IIa, level of evidence B). In the US, off-pump CABG is recommended in patients with renal impairment and as an option to reduce perioperative bleeding and need for transfusions.

The authors report no relevant financial relationships.


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