Mitigating Perioperative Stroke Risk in Patients Undergoing Non-Cardiac, Non-neurologic Surgery—Taking the Bull by the Horns

Perioperative stroke is a significant cause of morbidity and mortality and an increased risk for such a life altering event can limit patient willingness to undergo a necessary procedure.

Perioperative strokes occur in ~ 25,000 patients per year over the age of 45 who are undergoing non-cardiac surgery in the United States. Thirty-day mortality rates in patients who suffer a stroke attributable to perioperative causes, are as high as 26%. Recent studies have demonstrated a slightly upward trend in rate of perioperative stroke from 2004 to 2013^1,2. Infarcts that occur intra-operatively or within 30 days following non-cardiac and non-neurologic surgery can be clinically silent initially in 10% of patients, only to later result in cognitive impairment or be uncovered during a delayed neurological evaluation³. Patients with silent infarcts are twice as likely to develop cognitive impairment in prior studies². Advanced age, renal disease and prior stroke independently increase the risk for a perioperative ischemic stroke with hemorrhagic infarcts being much less common. Mechanisms of ischemia in these patients are not clearly established; often linked to hypoxia, hypotension or undiagnosed underlying vessel stenosis or risk factors⁴.

A practicing cardiologist and neurologist are often called upon to provide recommendations and perioperative risk assessment for a patient undergoing surgery. This highly nuanced, and much needed scientific statement by Benesch et al⁵ provides elegant guidance to neurologists and cardiologists alike to evaluate pre-operative neurologic risk, to implement intraoperative strategies to decrease stroke risk, and to adequately manage those who unfortunately experience a perioperative stroke. This guideline has simplified our approach in risk prediction and management and has clearly answered the following questions by analyzing current evidence.

1. How should we estimate the perioperative risk for stroke in our patients? The authors recommend using the American College of Surgeons surgical risk calculator that comprehensively incorporates underlying risk factors and disease states to provide a detailed risk percentage for various surgical complications including perioperative stroke⁶. In patients with prior stroke or TIA, another important consideration is the timing of surgery. Review of prior data suggests that non-elective surgeries be deferred at least 6-9 months while elective surgeries that lead to a quality-of-life benefit can be considered at the 6-month mark⁷.
2. How do underlying stroke risk factors contribute to stroke risk? The authors specifically evaluated data pertaining to patients with carotid stenosis, patent foramen ovale (PFO) and intracranial stenosis. As expected, existing literature demonstrates that high grade symptomatic carotid stenosis should be addressed surgically prior to any procedure while management of asymptomatic carotid stenosis is an ongoing area of research. With the evolution of intensive medical management strategies and the ongoing CREST-2 study, further guidance on managing asymptomatic carotid stenosis is awaited. The risk for perioperative stroke in patient with intracranial stenosis is unclear and can likely be ameliorated with intensive medical therapy. Patients with a PFO carry an increased perioperative risk but it is unclear if this risk is conferred due to an underlying cardiac risk. There is no clear data that high risk PFO’s as established by recent clinical trial criteria require closure prior to surgery ^8,9.
3. What about medications? It is recommended to continue beta blockers and statins; however, the discontinuation and re-initiation of antithrombotic therapy may vary by procedure-risk and thromboembolism-risk. The authors provide comprehensive guidance on when to stop and restart anticoagulation in patients based on these criteria ^10-12
4. What intra-operative strategies can help mitigate stroke risk? Hypotension and decreased cerebral perfusion are the most important risk predictors and it is recommended that the MAP be >=70mm Hg for patients at moderate to high risk. With surgery within one month of a stroke, hypotension should be avoided to prevent downregulation of cerebral blood flow. In cases of blood loss and patients with known vascular stenosis and occlusion, blood transfusion is recommended for Hemoglobin <8g/dl ^13-15.

All primary and comprehensive stroke centers employ a dedicated “stroke alert” process to activate teams of neurologists, radiologists and interventional specialists to rapidly evaluate and treat patients with all stroke types. The approach to perioperative stroke is no different and these patients need to be expeditiously evaluated for IV thrombolysis and endovascular thrombectomy (EVT). Bleeding risk at the surgical site needs to be discussed with the surgical team prior to administration of thrombolytics. Some patients with post-surgical strokes and large vessel occlusion will benefit from EVT without the bleeding risk of thrombolytics.

For clinicians who are often called upon to provide “surgical clearance”, this guideline can be used as a practical framework and can help us keep pace with the advancing complexity of stroke care; not only can we provide evidence-based recommendations to those getting tooth extractions but also to those who are undergoing more high risk non-cardiac, non-neurological procedures.