Inflammation and infection may predict post-thrombectomy mortality

By Tarun Sai LomteOct 12 2022Reviewed by Aimee Molineux

In a recent study published in Clinical Neurology and Neurosurgery, researchers assessed the association of markers of inflammation and infection with mortality in individuals with acute ischemic stroke post-thrombectomy.

Large vessel occlusion (LVO) carries a high morbidity/mortality risk and is observed in 20% to 40% of ischemic stroke cases. Clinical outcomes improve significantly in those with LVO after thrombectomy. Nevertheless, 15% to 20% of individuals with acute stroke die in less than three months after thrombectomy. Advanced age, increased infarct volume, and higher National Institutes of Health Stroke Scale (NIHSS) score at admission are factors predicting poor outcomes post-thrombectomy.

Inflammation and infection could potentially contribute to poor outcomes post-stroke. Infection could occur in up to 30% of hospitalized patients with ischemic stroke. Infection can aggravate outcomes after a stroke through systemic inflammation, resulting in secondary neurologic injuries. Multiple studies have demonstrated that poor post-stroke functional outcomes are associated with elevated markers of inflammation. Still, there is limited data on how inflammation and infection influence patient outcomes post-thrombectomy.

About the study

In the present study, researchers characterized the association between inflammation and infection markers and mortality in stroke patients after thrombectomy. They conducted a retrospective chart review of patients admitted for acute ischemic stroke between December 2018 and November 2020. Subjects were included if thrombectomy was attempted regardless of reperfusion and excluded if not.

Retrospective chart abstraction was performed to obtain demographic characteristics, stroke and hospitalization data such as NIHSS score at admission, the success of revascularization, discharge mortality, and markers of inflammation and infection. The thrombolysis in cerebral infarction (TICI) score was used to measure the success of revascularization. A TICI score of 2c or 3 meant successful revascularization.

Markers of inflammation and infection included leucocyte count and neutrophil percentage at admission, peak leucocyte count and fever during the hospital stay, days on antibiotic treatment, sputum, blood, and urine culture data, and severe acute respiratory syndrome coronavirus (SARS-CoV-2) test results. Infarct burden was evaluated on non-contrast computed tomography (CT) scans of the head obtained postoperatively by a neurologist using the Alberta Stroke Program Early CT Score (ASPECTS).

The association of discharge mortality with demographic characteristics, stroke data, and inflammation/infection markers was evaluated using a Fisher exact test or Student’s t-test; the Wilcoxon rank-sum test was used in the case of variables that are not distributed normally. Multivariable regression analyses tested for independent predictors of mortality. As a secondary analysis, the analyses were repeated, excluding coronavirus disease 2019 (COVID-19) patients.

Findings

There were 248 patients satisfying the inclusion criteria, and 41 (17%) died before discharge. Fourteen patients tested positive for SARS-CoV-2 and were excluded from the secondary analysis. In the primary (non-COVID-19) cohort, 34 patients died before discharge. Patients discharged alive had lower NIHSS scores at admission and were younger and less likely to have postoperative ASPECTS lower than 8.

There was a significant association of discharge mortality with higher median leucocyte count, neutrophil percentage, peak leucocyte count, and fever during admission. Results from the secondary analysis were similar except for leucocyte count at admission. In addition, patients who died before discharge were more likely to have a positive sputum, blood, or urine culture.

Nineteen patients had positive cultures, with (positive) sputum cultures accounting for about 95% of them. Moreover, the deceased patients were treated with antibiotics for longer than those discharged alive. SARS-CoV-2 infection was also associated with elevated mortality risk. Seven patients with COVID-19 (50%) died before discharge.

Secondary analysis revealed associations between positive cultures and the number of days on antibiotic treatment with discharge mortality. Multivariable analyses indicated a significant association of discharge mortality with leucocyte count, neutrophil percentage, peak leucocyte count, fever, and positive culture.

Multivariable analysis excluding COVID-19 patients showed a significant association of discharge mortality with fever, peak leucocyte count, and positive culture. The results of the multivariable analysis were similar when those with posterior circulation strokes were excluded (because ASPECTS is not relevant for these patients).  

Conclusions

In summary, the authors noted that discharge mortality in patients with acute ischemic stroke post-thrombectomy is associated with markers of inflammation and infection, independent of age, NIHSS score at admission, and ASPECTS. The study’s limitations include a small cohort size with patients from a single city. Nonetheless, the observed mortality rate approximates the anticipated mortality rate post-thrombectomy.

Overall, inflammation and infection post-thrombectomy in patients with acute ischemic stroke portends elevated discharge mortality risk. These results underscore the need to identify modifiable markers of inflammation and infection and further elucidate the mechanisms of post-stroke neurologic injury and inflammation to improve clinical outcomes.