Device-Related Thrombus After Left Atrial Appendage Closure: Incidence, Predictors, and Outcomes
Background—In patients with atrial fibrillation (AF), left atrial appendage closure (LAAC) with the Watchman device prevents thromboembolism from the LAA; however, thrombus may form on the left atrial face of the device, and then potentially embolize. Herein, we studied the incidence, predictors and clinical outcome of device-related thrombus (DRT) using a large series of clinical trial cohorts of patients undergoing Watchman implantation.
Methods—We studied the device arms of 4 prospective FDA trials: PROTECT-AF (n=463); PREVAIL (n=269); CAP (n=566); CAP2 (n=578). Surveillance TEEs were performed at 45 days and 12 months in all patients, and also at 6 months in the randomized control trials. We assessed both the incidence of DRT during these TEEs (and other unscheduled TEEs), and clinical outcomes of post-procedure stroke or systemic embolism (SSE) and adjusted for CHA2DS2-VASC and HAS-BLED scores.
Results—Of 1,739 pts that received an implant (7,159 pt-yrs FU; CHA2DS2-VASc = 4.0), DRT was seen in 65 pts (3.74%). The rates of SSE with and without DRT were 7.46 and 1.78 per 100 patient-years (adjusted rate ratio 3.55, 95% CI 2.18-5.79; P< 0.001), and ischemic SSE rates were 6.28 and 1.65 per 100 patient-years (adjusted rate ratio 3.22, 95% CI 1.90-5.45, P<0.001). On multivariable modelling analysis, the predictors of DRT were: history of transient ischemic attack or stroke (OR 2.31, 95% CI 1.26-4.25, P=0.007), permanent AF (OR 2.24, 95% CI 1.19-4.20, P=0.012); vascular disease (OR 2.06, 95% CI 1.08-3.91, P=0.028); LAA diameter (OR 1.06 per mm increase, 95% CI 1.01-1.12, P=0.019); LVEF (OR 0.96 per 1% increase, 95% CI 0.94-0.99, P=0.009). DRT and SSE both occurred in 17 of 65 pts (26.2%). Of the 19 SSE events in these DRT patients, 9 of 19 (47.4%) and 12 of 19 (63.2%) occurred within 1 and 6 months of DRT detection. Conversely, after LAAC, most SSEs (123 of 142, 86.62%) occurred in patients without DRT.
Conclusions—After LAAC with Watchman, DRT (~3.7%) is not frequent, but when present, is associated with a higher rate of stroke and systemic embolism.
- Received April 6, 2018.
- Revision received April 23, 2018.
- Accepted May 3, 2018.