Patients undergoing major vascular surgery procedures are at increased risk of stroke, leading to a high mortality rate and prolonged hospitalization, according to a study in the February issue of Anesthesia & Analgesia, official journal of the International Anesthesia Research Society (IARS).
But the risk factors for stroke associated with vascular surgery -- such as old age or a history of previous heart disease or stroke -- are not "readily modifiable," reports the study by Dr Milad Sharifpour and colleagues of University of Michigan Medical Center, Ann Arbor.
Study Shows High Impact of Stroke after Vascular Surgery
Using a large surgical database -- the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP®) -- the researchers identified nearly 46,000 patients undergoing vascular surgery at U.S. hospitals between 2005 and 2009. The study focused on specific types of procedures involving the major blood vessels: amputation or blood vessel reconstruction of the leg or aneurysm repair or other procedures on the aorta.
The goal was to assess the risk of stroke associated with these major vascular procedures, and to identify patient characteristics and conditions associated with particularly high risk. Because many patients undergoing vascular surgery have atherosclerosis or other known risk factors for stroke -- such as high blood pressure, coronary artery disease, or diabetes -- they are expected to be at high risk of stroke. (The study specifically excluded patients undergoing heart surgery, as well as carotid artery surgery for prevention or treatment of stroke.)
The overall risk of stroke within 30 days after vascular surgery was relatively low: 0.6 percent. However, this rate was about six times higher than in previous studies of patients undergoing nonvascular surgical procedures.
When stroke did occur, it had a major adverse effect on patient outcomes. For patients with stroke after vascular surgery, the risk of death was more than three times higher than for matched patients without stroke. Stroke after vascular surgery was also associated with prolonged recovery time: median hospital stay was 13 days in patients with stroke, compared to six days for those without stroke.
More Research Needed to Show 'Modifiable' Risk Factors
The study identified several risk factors for stroke after vascular surgery, including older age and female sex. Risk was also higher for patients with a previous history of stroke and those with kidney failure. About half of all strokes occurred on second through eighth days after vascular surgery.
For patients undergoing any type of surgery, stroke is a "potentially catastrophic" complication. The new results confirm that vascular surgery patients are a group at high risk of stroke, which puts them at increased risk of death and prolonged hospitalization.
The study identifies independent risk factors for stroke, but none of them are "potentially modifiable." Although the information may help the surgical team to identify vascular surgery patients at higher risk of stroke, they don't provide any opportunity to lower the risk of stroke for individual patients. "Further studies are needed to identify modifiable postoperative risk factors to reduce the incidence and sequelae of stroke," Dr Sharifpour and coauthors write.
In an accompanying editorial, Dr John C. Drummond of University of California raises key issues related to research using large electronic databases, such as the NSQIP. He identifies several potential sources of bias associated with such "armchair research" using information collected for other purposes.
Nevertheless, Dr Drummond believes the study by Sharifpour and colleagues is "legitimately hypothesis-generating" -- identifying new treatments with the potential to reduce the risk of stroke after vascular surgery. One promising approach may be new approaches to antithrombotic (anti-clotting) therapy during the high-risk period between two and eight days after surgery.
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