Table 1.

Study characteristics and validity criteria.

Study	Type of Study	>80% of Patients Received TEE	Tee Masked to Clinical Reviewer	Internal Validity @	External Validity (for Referral Center) #
		Criteria for Internal Validity		Class $
Marino et al., 2016 [17]	Retrospective	Yes	No	II	Minor
Gaudron et al., 2014 [18]	Prospective	No	No	II	Minor
Zhang et al., 2012 * [19]	Retrospective	No	No	II	Minor
Knebel et al., 2009 [20]	Retrospective	Yes	No	II	Minor
de Bruijn et al., 2006 [6]	Prospective	Yes	No	II	Minor
Blum et al., 2004 [12]	Retrospective	Yes	No	II	Moderate
de Abreu et al., 2008 [21]	Prospective	No	No	II	Moderate
Harloff et al., 2006 [14]	Prospective	Yes	No	III	Minor
Shyu et al., 1993 * [22]	Prospective	Yes	No	III	Minor
Rauh et al., 1996 [23]	Prospective	Yes	No	III	Minor
Cujec et al., 1991 * [24]	Prospective	Yes	No	III	Minor
Pop et al., 1990 * [25]	Prospective	Yes	No	III	Minor
Pearson et al., 1991 * [26]	Prospective	Yes	No	III	Moderate
Censori et al., 1998 * [27]	Prospective	No	No	III	Moderate
Retting et al., 2008 [28]	Retrospective	Yes	No	III	Moderate
Total: 15 studies

* Patients/data were taken from the subgroup analysis only for patients meeting study criteria (without evidence of atrial fibrillation and/or heart disease and/or without indication for anticoagulation prior to TEE). ^@ Internal validity was defined by three parameters (type of the study, if >80% of participants in the study received TEE, and if TEE was masked to clinical reviewer). ^# External validity was defined by the patient population enrolled in the study keeping the stroke referral center as standard. ^$ The class of the study was determined based on the above-mentioned internal validity parameters.