On- and off-pump CABG outcomes similar
MedWire News: US research has shown that on-pump coronary artery bypass grafting (CABG) using cardiopulmonary bypass (CBP) is associated with similar outcomes to off-pump coronary artery bypass grafting (OPCAB).
The study revealed similar graft patency, incidence of myocardial ischemia, need for reintervention, and survival in patients who underwent CABG using CPB and those who underwent OPCAB over the 8-year follow-up.
Although OPCAB received much interest in the 1990s due to its avoidance of many of the morbidities associated with CPB, write John Puskas (Emory University School of Medicine, Atlanta, Georgia) and colleagues, its adoption rates have waned in recent years.
The authors believe that this is due to the technically challenging nature of OPCAB, and because recent trials have not shown a significant difference in major adverse cardiac event (MACE) outcomes.
"Despite the fact that these trials were underpowered to assess MACE, the absence of significant differences in these hard end points in randomized controlled trials was taken as evidence of absence of real benefit for OPCAB," they say.
The present study, a follow-up of the Surgical Management of Arterial Revascularization Therapies (SMART) trial, set out to compare long-term survival, graft patency, myocardial ischemia, and clinical outcomes among SMART survivors.
It included 200 unselected SMART patients, who were randomly assigned to OPCAB or CPB between March 2000 and August 2001, and who volunteered to return for clinical evaluation and imaging studies.
Of 140 SMART survivors, 87 returned for the present study, in which graft patency and myocardial ischemia were assessed after a mean period of 7.5 years. The mean age of the patients at follow-up was 68 years.
The findings showed that as of March 30, 2009, there were 31 all-cause deaths among CPB patients and 26 among OPCAB patients. Graft patency was similar between CPB and OPCAB groups before hospital discharge (97.7 vs 99.0%), at 1 year (95.8 vs 93.6%), and at 8-year follow-up (83.5 vs 76.0%).
Incidence of recurrent ischemia throughout follow-up was also similar, with 35.3% of OPCAB and 41.0% of CPB patients experiencing any ischemia upon positron emission tomography scanning. Of the OPCAB patients, 11.8% had an ischemic region in excess of 10% of the myocardium compared with 23.1% of the CPB patients.
Percutaneous reintervention was performed in the same percentage of OPCAB and CPB patients (2.3%). It was not necessary to perform repeat coronary artery bypass graft (CABG) in either group.
"Specifically, the index of completeness of revascularization was similar between groups overall and for the lateral wall of the left ventricle, an area of the heart often considered more difficult to graft off-pump," explain Puskas et al.
They point out that a limitation of their study lies in its small sample size, and the significant attrition of patients during the course of the trial.
"Conclusions from this trial must be drawn carefully and generalized cautiously," they say.
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By Piriya Mahendra