History of ischemic stroke raises risk of adverse events after noncardiac surgery

A history of ischemic stroke, especially within the previous 9 months, was associated with a higher risk of adverse events after noncardiac surgery, a new study found.

Danish researchers used national registry data of all elective noncardiac surgeries (n=481,183 surgeries) performed in patients aged 20 years or older in 2005-2011. Using ICD-10 codes, they identified patients with prior ischemic stroke; they didn't include patients with hemorrhagic stroke or transient ischemic attack. Patients whose last stroke occurred more than 5 years before surgery weren't included.

The researchers divided patients into subgroups based on time elapsed between stroke and surgery. The groups were no prior stroke, stroke within less than 3 months, stroke within 3 to less than 6 months, stroke within 6 to less than 12 months, and stroke 12 or more months before surgery. The primary outcomes were all-cause mortality and major adverse cardiovascular events (MACE) up to 30 days after surgery. MACE was a combination of nonfatal acute myocardial infarction, nonfatal ischemic stroke, and cardiovascular death. Results were published online July 16 by the Journal of the American Medical Association.

Among patients with prior stroke (n=7,137), the crude incidence rate of MACE was 54.4 per 1,000 patients, compared to patients without prior stroke (n=474,046) for whom the MACE incidence rate was 4.1 per 1,000. Regardless of time between ischemic stroke and surgery, a prior ischemic stroke was associated with an adjusted 1.8- and 4.8-fold increased relative risk of 30-day mortality and 30-day MACE, respectively, compared with patients without prior stroke.

There also was a strong time-dependent relationship between previous stroke and adverse postoperative outcome, with patients who had a stroke less than 3 months before surgery at especially high risk. Compared to patients without stroke, odds ratios for MACE were 14.23 (95% CI, 11.61 to 17.45) for patients with stroke less than 3 months before surgery, 4.85 (95% CI, 3.32 to 7.08) for stroke 3 to less than 6 months prior, 3.04 (95% CI, 2.13 to 4.34) for stroke 6 to less than 12 months prior, and 2.47 (95% CI, 2.07 to 2.95) for stroke 12 months or more prior. In those same subgroups, 30-day mortality risks followed a similar pattern; odds ratios were 3.07 (95% CI, 2.30 to 4.09), 1.97 (95% CI, 1.22 to 3.19), 1.45 (95% CI, 0.95 to 2.20), and 1.46 (95% CI, 1.21 to 1.77), respectively. Risks for MACE and death were elevated but level after 9 months. MACE risk didn't vary by whether the surgery itself was low-, intermediate- or high-risk.

Studies looking into the optimal timing of surgery in patients with prior stroke are scarce, the authors noted. These results suggest patients should be considered at higher risk of adverse 30-day outcomes after noncardiac surgery until 9 months after stroke, the authors concluded. Given that low- and intermediate-risk surgeries appeared to pose the same risk of MACE as high-risk surgeries, “it seems important to take a history of recent stroke seriously, including in the context of minor surgical procedures,” the authors wrote.