Parneet Grewal, MD
Perioperative stroke has been linked to increased mortality and morbidity in patients undergoing surgical procedures. A number of cardiovascular risk assessment tools, such as Revised Cardiac Risk Index (RCRI)1, the myocardial infarction or cardiac arrest (MICA) calculator1, the American College of surgeons surgical risk calculator (ACS-SRC), and Mashour et al. risk score,2 have been published to predict perioperative complications. CHADS2 and CHA2DS2-VASc risk scores have also been shown to improve prediction of postoperative stroke in patients undergoing cardiac procedures even in absence of atrial fibrillation3. In this retrospective study, Wilcox et al. aimed to compare the effectiveness of existing cardiovascular risk stratification scores in predicting risk of perioperative stroke after non-cardiac surgery.
Data was collected from American College of Surgeons National Quality Improvement Project (NSQIP)4, and included patients aged >18 years who underwent non cardiac surgeries (general, gynecologic, neurological, orthopedic, otolaryngological, plastic, thoracic, urological and vascular surgery) from year 2009 to 2010. The authors found that perioperative stroke occurred in 1474 (0.27%) cases out of 540717 with stroke patients having higher 30 day mortality (22.3% vs 1.6%; p<0.0001), increased length of stay (10 vs 2 days; p<0.0001), higher rate of myocardial infarction (2.85% vs 0.5%; p<0.0001), cardiac arrest, pneumonia, unplanned reintubation, sepsis, septic shock, pulmonary embolism, and deep vein thrombosis. Risk factors for having a perioperative stroke in this study sample were older age (69.7±12.9 vs 57.7±16.6; p<0.001), male sex (48.6% vs 43.2%; p<0.001), and lower BMI (28.1±7.0 vs 29.8±8.1; p<0.001). On comparing all the risk assessment scores, MICA and ACS-SRC scores had the highest discriminative accuracy for perioperative stroke (AUC >0.8 for general, gynecologic, otolaryngology, and plastic surgery types, AUC >0.7 for neurological, orthopedic, thoracic, and urologic subtypes). The other important finding was that the most common surgical procedure associated with perioperative stroke was vascular surgery, and all risk scores had poor discriminative accuracy for stroke in these patients (AUC<0.7).
The authors rightfully acknowledge the limitations of this study, which include retrospective analysis of a database that was designed mainly for quality improvement purposes with potential for sampling, reporting, and recall bias along with unmeasured confounders such as preoperative statin or beta blocker use. This database may also provide advantage to MICA, ACS-SRC, and Mashour scores over other scores since they have been validated in this patient population.
The study illustrated the importance of assessing stroke risk in perioperative period so that optimal interventions may be attempted to decrease that risk. Further research is needed to accurately establish scores for vascular surgery along with prospective validation of MICA and ACS-SRC scores in perioperative stroke risk assessment in patients undergoing non-cardiac surgery.
1. Gupta PK, Gupta H, Sundaram A, Kaushik M, Fang X, Miller WJ, et al. Development and validation of a risk calculator for prediction of cardiac risk after surgery. Circulation. 2011;124:381-387.
2. Mashour GA, Shanks AM, Kheterpal S. Perioperative stroke and associated mortality after noncardiac, nonneurologic surgery. Anesthesiology. 2011;114:1289-1296.
3. Peguero JG, Issa O, Podesta C, Elmahdy HM, Santana O, Lamas GA. Usefulness of the cha2ds2vasc score to predict postoperative stroke in patients having cardiac surgery independent of atrial fibrillation. Am J Cardiol. 2015;115:758-762.
4. Bilimoria KY, Liu Y, Paruch JL, Zhou L, Kmiecik TE, Ko CY, et al. Development and evaluation of the universal acs nsqip surgical risk calculator: A decision aid and informed consent tool for patients and surgeons. J Am Coll Surg. 2013;217:833-842.e831-833.