Background: The smoking-paradox of a better outcome in ischemic stroke patients who smoke may be due to increased efficacy of thrombolysis. We investigated the effect of smoking on outcome following endovascular therapy (EVT) with mechanical thrombectomy alone versus in combination with intra-arterial (IA-) thrombolysis.
Methods: The primary endpoint was defined by three-month modified Rankin Scale (mRS). We performed a generalized linear model and reported relative risks (RR) for smoking (adjustment for age, sex, hypertension, atrial fibrillation, stroke severity, time to EVT) in patient data stemming from the Virtual International Stroke Trials Archive-Endovascular database.
Results: Among 1,497 patients, 740(49.4%) were randomized to EVT; among EVT patients, 524(35.0%) received mechanical thrombectomy alone and 216(14.4%) received it in combination with IA-thrombolysis. Smokers (N = 396) had lower mRS scores (mean 2.9 vs. 3.2; p = 0.02) and mortality rates (10% vs. 17.3%; p<0.001) in univariate analysis. In all patients and in patients treated with mechanical thrombectomy alone, smoking had no effect on outcome in regression analyses. In patients who received IA-thrombolysis (N = 216;14%), smoking had an adjusted RR of 1.65 for an mRS<less than or equal to>1 (95%CI 0.77-3.55). Treatment with IA-thrombolysis itself led to reduced RR for favorable outcome (adjusted RR 0.30); interaction analysis of IA-thrombolysis and smoking revealed that non-smokers with IA-thrombolysis had mRS ≤ 2 in 47 cases (30%, adjusted RR 0.53 [0.41-0.69]) while smokers with IA-thrombolysis had mRS ≤ 2 in 23 cases (38%, adjusted RR 0.61 [0.42-0.87]).
Conclusions: Smokers had no clear clinical benefit from EVT that incorporates IA-thrombolysis.