NEJM: More targeted CABG strategies needed to minimize stroke, cognitive decline
“Stroke continues to be a major complication of otherwise successful cardiac surgical procedures,” Ola A. Seines, PhD, of Johns Hopkins University School of Medicine in Baltimore, and colleagues wrote. “Prediction models for stroke have been available for some time, but individualized surgical-management strategies based on preoperative or perioperative screening have only recently become widely used in an effort to reduce this serious neurologic outcome. From the preoperative to the postoperative period, the care of patients undergoing CABG is still far from standardized.”
The authors reviewed the pathophysiology of these adverse outcomes and current and emerging strategies for improving outcomes. Factors associated with the risk of postoperative stroke include older age, a history of tobacco use, hypertension, diabetes and anemia, they noted. They suggested that in some cases the health of blood vessels in the neck, brain and surrounding the heart may play a role in postoperative neurologic complications.
They observed that randomized trials have found that off-pump CABG did not decrease the rate of postoperative stroke, while other nonrandomized trials showed off-pump surgery was associated with lower rates of early stroke but not delayed stroke.
“The mechanisms of stroke after on- and off-pump surgery may thus be slightly different,” Seines and colleagues wrote. “The finding that stroke rates are similar, however, supports the concept that patient-related factors, including arteriosclerotic burden, are more important predictors of the risk of stroke than is the type of surgery.”
Medical strategies for preventing postoperative stroke and adverse cognitive outcomes include prescribing statins and aspirin, but the use of statins is controversial, they wrote, as is the use of aspirin during surgery. Imaging modalities such as intraoperative epiaortic ultrasonography, duplex ultrasonography, near-infrared spectroscopy and transcranial Doppler are potentially helpful tools for guiding surgical and treatment decisions, but outcomes based on use of some of these techniques have not been assessed in randomized trials.
Research has shown that many patients referred for CABG already have cognitive impairment which the authors proposed could be a surrogate marker of cardiovascular disease. “Because pre-existing, undiagnosed silent infarctions and small-vessel disease are risk factors for adverse neurologic outcomes, it has been proposed that preoperative cognitive testing may be a cost-efficient means of identifying high-risk patients.”
Additionally, the root of postoperative cognitive declines may lie in preoperative cerebrovascular disease rather than the CABG procedure, they wrote.
“Although the pathogenesis of adverse neurologic events after CABG is probably multifactorial, there is growing evidence that patient-related risk factors, such as the extent of pre-existing cerebrovascular and systemic vascular disease, have a greater effect on both short- and long-term neurologic sequelae than do procedural variables, such as on-pump versus off-pump surgery,” they concluded. “Therefore, the risk of postoperative stroke or cognitive decline should not be a factor in the choice of surgical therapy for coronary artery disease.”
Based on their review, they recommended that to potentially improve patients’ neurologic and cognitive outcomes, physicians:
- Preoperatively assess a patient’s known risk factors, including a history of anemia, cerebrovascular disease and infarcts;
- Preoperatively screen patients for cognitive impairments that may be the result of underlying cardiovascular or cerebrovascular disease; and
- Provide postoperative care to control modifiable risk factors for cerebrovascular disease, such as diet, exercise, blood pressure and cholesterol.