Abstract 113: Detection Of Patent Foramen Ovale In Patients With Ischemic Stroke On Prospective ECG-gated Cardiac CT Compared To Transthoracic Echocardiography

Abstract

Background: Cardiac CT acquired during the acute stroke imaging protocol is an emerging alternative to transthoracic echocardiography (TTE) to screen for sources of cardioembolism, but its diagnostic accuracy to detect patent foramen ovale (PFO) is unclear. Methods: This was a substudy of Mind the Heart, a prospective single-center cohort study in which consecutive adult patients with acute ischemic stroke underwent prospective ECG-gated cardiac CT during the initial stroke imaging protocol. Patients also underwent routine work-up, including TTE. We included patients <60 years who underwent TTE with agitated saline contrast (cTTE). Presence of a PFO on CT and cTTE was scored according to predefined criteria by a cardioradiologist and cardiologist, respectively, who were blinded to each other’s scoring. On CT, PFO was defined as a crypt shaped contrast jet from the left atrium to the right atrium towards the vena cava or an atrium septum discontinuity. On cTTE, a PFO was defined as the appearance of microbubbles in the left atrium within 3-6 cardiac beats after opacification of the right atrium. We assessed the sensitivity and specificity of cardiac CT for the detection of PFO using cTTE as the reference standard. Results: Of 452 patients in Mind the Heart, 92 were younger than 60 years. Of these, 56 (61%) patients underwent both cardiac CT and cTTE and were included. Median age was 55 (interquartile range [IQR] 49-57) years and 38 (68%) were male. In total, 32/56 (57%) patients had cryptogenic stroke and their median Risk of Paradoxical Embolism score was 6 (IQR 6-7). Cardiac CT detected a PFO in 5/56 (9%) patients, 3 of which were confirmed on cTTE. cTTE detected a PFO in 12/56 (21%) patients. The sensitivity and specificity of cardiac CT were 25% (95%CI: 5-57%) and 95% (95%CI: 85-99%), respectively. Positive and negative predictive value were 59% (95%CI: 22-87) and 83% (95%CI: 77-87), respectively Conclusion: Due to its low sensitivity, prospective ECG-gated cardiac CT does not appear to be a suitable screening method for PFO. If cardiac CT is used to screen for cardioembolism, additional echocardiography remains indicated in patients with cryptogenic stroke in whom PFO detection would have therapeutic consequences.