Author + information
- Jian-Fang Ren, MD⁎ ()
- ↵⁎Division of Cardiovascular Medicine, University of Pennsylvania Health System, 111 N 9th Street, Philadelphia, Pennsylvania 19107
I read with interest the report by Viles-Gonzalez et al. (1), which indicated that residual peri-device flow into the left atrial appendage (LAA) after percutaneous closure with the Watchman device was common, and not associated with an increased risk of thromboembolism. Transesophageal echocardiography (TEE) was performed, and follow-up revealed that 32% of implanted patients had at least some degree of peri-device flow (“leak”) at 12 months. Although such observations are unique with a large sample available from the PROTECT AF (WATCHMAN Left Atrial Appendage System for Embolic Protection in Patients With Atrial Fibrillation) trial, the methodology and analytical data used to reach conclusions regarding risk of thromboembolism warrant further discussion.
Accurate echocardiographic measurement of the LAA anatomy, especially of the ostium, is critically important for successful LAA ostial closure using the Watchman device. The echocardiographic ostium of the LAA, which is usually measured from the junction of the upper left pulmonary vein entering the LA to the junction of the LA and LAA, is somewhat larger than the anatomic ostium (2). The maximal LAA ostial diameter can be obtained and used as an accurate reference for LAA ostial diameter measured at baseline from TEE or intracardiac echocardiographic (ICE) LAA imaging views (3,4) (Fig. 1A). Viles-Gonzalez et al. (1) indicated that “there was a wide variation on the size of the LAA ostium width and length at baseline” and reported that “the mean LAA ostium width at baseline was 21.9 ± 4.1 mm…The mean ostium length at baseline was 49.4 ± 9.1 mm.” Obviously, such a large ostium length could not exist even in patients with atrial fibrillation (AF) and would be impossible to close with the largest Watchman device (33 mm). However, these LAA diameters are comparable with our measurements of the maximal short (18 ± 4 mm) and long (50 ± 9 mm) axes of LAA body size in patients with AF (n = 42) using ICE imaging. The question is whether they measured the LAA ostium or just the LAA body size.
Regarding peri-device flow (leak), Viles-Gonzalez et al. (1) explained that a peri-device flow would be the mismatch between the circular device and the typically oval LAA orifice and the subsequent inadequacy of circumferential LAA sealing. I disagree with this explanation of “shape mismatch” conception. Accurate measurement of maximal LAA ostial diameter is much more important than shape, because the LAA ostium is mainly a soft tissue structure that can be expanded and fit completely to the device shape if the device is placed at an optimal location. ICE LAA ostium imaging with color Doppler flow can reliably confirm the optimal location without any peri-device flow. Of note, to evaluate the peri-device flow (leak), LAA emptying flow is more important than the “fill-in flow,” which was only illustrated in their Figure 2 (1), because such a fill-in flow may be a slight “pit” and does not necessarily indicate a flow communicating to the closed LAA (Fig. 1B).
Although the investigators should be congratulated for reporting on such a large cohort of patients who underwent LAA device closure, I found the LAA ostium length measurements biased and peri-device flow unconfirmed against the patients who had common peri-device flow (leak). These factors significantly impair the power of this study and put into question the accuracy of their conclusion.
- American College of Cardiology Foundation
- Viles-Gonzalez J.F.,
- Kar S.,
- Douglas P.,
- et al.
- Veinot J.P.,
- Harrity P.J.,
- Gentile F.,
- et al.
- Hutchison M.D.,
- Callans D.J.