Detection of Left Ventricular Thrombus by Cardiac Magnetic Resonance in Embolic Stroke of Undetermined Source

Background and Purpose— We aimed to use contrast-enhanced cardiac magnetic resonance (CE-CMR) imaging to elucidate the prevalence of left ventricular (LV) thrombus in patients suspected of embolic stroke of undetermined source (ESUS) with previous myocardial infarction or LV dysfunction (LV ejection fraction LVEF <50%). Methods— We prospectively investigated 797 consecutive patients who presented to our hospital with acute ischemic stroke between 2014 and 2015. Patients with myocardial infarction or LVEF<50% underwent CE-CMR imaging. ESUS was diagnosed according to proposal criteria based on transthoracic echocardiography findings. Results— The prevalence of ESUS was 22% (178 of 797) on initial diagnosis. Among 60 patients with myocardial infarction or LVEF<50%, the stroke subtypes were as follows: small artery disease, 17% (10 of 60); large artery atherosclerosis, 5% (3 of 60); cardioembolic stroke, 49% (29 of 60); ESUS, 23% (14 of 60); and undetermined causes other than ESUS, 6% (4 of 60). Of 60 patients examined via CE-CMR, LV thrombus was confirmed in 12 patients, whereas only 1 had been detected on transthoracic echocardiography ( P =0.04). Importantly, 29% (4 of 14) of patients with ESUS had LV thrombus. A prediction model based on CE-CMR findings showed higher performance in LV thrombus detection, permitting a net improvement of 0.46 (95% confidence interval, 0.08–0.82; P =0.016) in cardioembolic stroke reclassification. Compared with patients without LV thrombus, those with LV thrombus had lower LVEF (median: 26% versus 40%; P =0.003). Notably, 42% (5 of 12) of patients with LV thrombus had LVEF≥30%. Conclusions— When ESUS-suspected patients have myocardial infarction or LV dysfunction, CE-CMR may help improve detection of cardioembolic stroke and provide relevant information for anticoagulation therapy. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT02251665.