Is low cardiac ejection fraction a risk factor for stroke?

Abstract

Background and Purpose: Reduced ejection fraction (EF) ?35% has been suggested as a criterion for anticoagulation in persons with heart failure in sinus rhythm, but the literature supporting EF as an independent stroke risk factor is conflicting. We here review the status of reduced EF as a stroke risk factor. Methods: We performed a Medline search combining terms for stroke and heart failure (HF) or cardiac left ventricular systolic dysfunction and reviewed evidence that reduced EF increases the risk of stroke. We also reviewed clinical and epidemiological HF studies that included data on stroke and EF. Results: Two of three longitudinal cohort studies found reduced EF (<50%) to be a stroke risk factor but did not find an inverse relationship between EF level and degree of stroke risk. Exploratory analyses of three clinical studies found an inverse relationship between EF level and degree of stroke risk but only in specific subgroups and vascular risk factors appeared to attenuate this relationship. Three analyses suggested an increased stroke risk with EF ?20%. Conclusion: Reduced EF (<50%) probably increases stroke risk but this is not consistently demonstrated in all populations studied. Reduced EF of any degree may be a surrogate for atherosclerotic cerebrovascular disease and in these patients traditional vascular risk factors may be more important for stroke risk than EF. There is no evidence to support EF ?35% as a specific stroke risk factor. Research is needed to determine if very reduced EF (?20%) is a specific stroke risk factor.