Impact of smoking on outcomes following endovascular therapy for acute ischemic stroke: A systematic review and meta-analysis

Background: Smoking represents a leading risk factor for acute ischemic stroke (AIS). Previous literature has described a “smoking paradox”, wherein smokers experience better outcomes following intravenous thrombolysis for AIS. It is unclear whether such a phenomenon exists in smokers undergoing endovascular therapy (EVT) for AIS. To assess outcomes in smokers following EVT for AIS, we conducted a systematic review and meta-analysis. Methods: Following the PRISMA guidelines, a systematic literature review of the English language literature was conducted using PubMed, Embase Web of Science, and Scopus. Outcomes of interest included 90-day modified Rankin Scale (mRS) 0–2, thrombolysis in cerebral infarction (TICI) score 2b-3, symptomatic intracranial hemorrhage (sICH), and mortality. We calculated mean difference (MD), pooled odds ratios (ORs) and their corresponding 95% confidence intervals (CI). Results: Eight studies with 2633 patients comprised our analysis. On average, smokers were 10.14 years (MD = 10.14, [95% CI = −14.49 to −5.79], P-value < 0.001) younger than non-smokers. Smokers achieved mRS 0–2 (OR = 1.82, [95% CI, 1.34–2.48], P-value < 0.001) and TICI 2b-3 (OR = 1.61, [95% CI, 1.19–2.19], P-value = 0.002) at a higher rate than non-smokers. sICH rates were comparable between smokers and non-smokers (OR = 1.07, [95% CI, 0.62–1.85], P-value = 0.81). Smokers had a lower rate of 90-day mortality than non-smokers (OR = 0.54, [95% CI, 0.41–0.71], P-value < 0.001). Conclusions: In this meta-analysis of eight studies, we found that smokers with AIS undergoing EVT experienced better 90-day outcomes and higher rates of TICI 2b-3. This may be due to baseline differences between smokers and non-smokers, but future studies should explore alternative reasons that could explain this relationship between smoking and AIS treated with EVT.