To the Editor,

We would like to thank the authors of the comment on our study for the interest they have shown in our work,1 as well as the Editorial Board of the journal for providing us with the opportunity to respond.

We are largely in agreement with the comments that they make, but we would nevertheless like to clarify the following points:

• 1. The ostium of the left appendage is, as they stated, not completely circular in most patients, but it is nevertheless flexible enough to adapt to the circular geometry of the device.

• 2. The self-expanding nitinol devices used for closure of cardiovascular defects (atrial and ventricular shunting, patent ductus arteriosus, vascular stenosis, etc.) are self-centering and adapt to the shape (not necessarily circular) of the abnormalities that they are intended to treat. This same principle explains the effectiveness of the Amplatzer Cardiac Plug (ACP) for closure of the left atrial appendage.

• 3. The devices used are semipatent, and so they initially allow a small residual flow. The observations made by 2D, 3D, and Doppler color echocardiography show complete closure (absence of flow) in the appendage in more than 95% of cases,2 once the adaptation of the ACP to the appendage has been accomplished and subsequent endothelization and organization has occurred. We therefore think that the moment to define whether or not flow is present is after 3 months have passed, and this is when we should judge whether complete closure has occurred.

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Corresponding author: calmeria.hcsc@salud.madrid.org