Smoking-Thrombolysis Paradox

Abstract

BACKGROUND AND PURPOSE: The so-called smoking-thrombolysis paradox of an improved outcome after thrombolysis was first described in smokers with myocardial infarction. We investigated whether reperfusion rates and clinical outcome differ between smokers and nonsmokers with ischemic stroke after intravenous tissue plasminogen activator. METHODS: Consecutive acute ischemic stroke patients, who had magnetic resonance imaging before and 1 day after thrombolysis, were included for analysis. All of the patients received intravenous tissue plasminogen activator within 4.5 hours. Reperfusion was defined as a 75% reduction in perfusion deficit (mean transit time >6 s) after thrombolysis compared with baseline. Magnetic resonance angiography was used to evaluate arterial stenosis and occlusion. Functional outcome was assessed 3 months after stroke using the modified Rankin Score. RESULTS: Of 148 patients, 21.6% were smokers (n=32). Smokers were younger (median, 61 years [SD, 9.4 years] versus 75 years [SD, 11.6 years]; P<0.001), less often women (28% versus 51%; P=0.03), had lower baseline glucose levels (median, 6.2 mmol/L [interquartile range, 5.7-6.8 mmol/L] versus 6.7 mmol/L [interquartile range, 6.1-8.2 mmol/L]; P<0.01) and higher baseline perfusion deficits (median, 53 mL [interquartile range, 13-141 mL] versus 17 mL [interquartile range, 2-66 mL]; P=0.04). In a backward stepwise regression analysis including age, sex, hypertension, glucose, perfusion deficit, and smoking, smoking had an odds ratio of 4 (95% confidence interval, 1-16; P=0.03) for reperfusion and 6 (95% confidence interval, 1-30; P=0.05) for recanalization (regression analysis for recanalization also included localization of arterial occlusion). Smokers had a better outcome (modified Rankin Score=0-2) than nonsmokers (77% versus 55%; P=0.05). CONCLUSIONS: Smoking is independently associated with recanalization and reperfusion, indicating that thrombolytic therapy acts more effectively in smokers; because of small numbers, these results should be considered preliminary. Clinical Trial Registration- URL: http://clinicaltrials.gov. Unique Identifier: NCT00715533.