ABSTRACT: BACKGROUND:Heart failure (HF) is a risk factor for atrial fibrillation (AF), stroke, and post-stroke disability. However, differing definitions and application of HF-criteria may impact model prediction. We compared the predictive ability of left ventricular ejection fraction (LVEF), a readily available objective echocardiographic index, with clinical HF definitions for functional disability and AF in stroke patients. METHODS:We retrospectively analyzed ischemic stroke patients evaluated between January 2013 and May 2015. Outcomes of interest were: (a) 90-day functional disability (modified Rankin score 3-6) and (b) AF. We compared: (1) LVEF (continuous variable), (2) left ventricular systolic dysfunction (LVSD)-categories (absent to severe), (3) clinical history of HF, and (4) HF/LVSD-categories: (i) HF absent without LVSD, (ii) HF absent with LVSD, (iii) HF with preserved ejection fraction (HFpEF), and (iv) HF with reduced ejection fraction (HFrEF). Multivariable logistic regression was used to determine the predictive ability for 90-day disability and AF, respectively. RESULTS:Six hundred eighty five consecutive patients (44.5% female) fulfilled the study criteria and were included. After adjustment, the LVEF was independently associated with 90-day disability (OR .98, 95% CI .96-.99, P?=?.011) with similar predictive ability (area under the curve [AUC]?=?.85) to models including the LVSD-categories (AUC?=?.85), clinically define HF (AUC?=?.86), and HF/LVSD-categories (AUC?=?.86). The LVEF, HF, LVSD-, and HF/LVSD-categories were independently associated with AF (P < .01, each) with similar predictive ability (AUC?=?.74, .74, .73, and .75, respectively). CONCLUSIONS:Compared to commonly defined HF definitions, the objectively determined LVEF possesses comparable predictive ability for 90-day disability and AF in stroke patients.