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Device-Related Thrombus After LAA Closure
Study Questions:
What is the incidence, predictors, and clinical outcome of device-related thrombus (DRT) among patients undergoing Watchman implantation?
Methods:
The investigators studied the device arms of four prospective FDA trials: PROTECT-AF (n = 463), PREVAIL (n = 269), CAP (n = 566), and CAP2 (n = 578). Surveillance transesophageal echocardiograms (TEEs) were performed at 45 days and 12 months in all patients, and also at 6 months in the randomized controlled trials. They 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. DRT was modeled on baseline variables using a generalized estimating equation, accounting for correlation among subjects from the same study, with a binary distribution and a logit link function.
Results:
Of 1,739 patients who received an implant (7,159 patient-years of follow-up; CHA2DS2-VASc = 4.0), DRT was seen in 65 patients (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% confidence interval [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 modeling analysis, the predictors of DRT were: history of transient ischemic attack (TIA) or stroke (odds ratio [OR], 2.31; 95% CI, 1.26-4.25; p = 0.007), permanent atrial fibrillation (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), and left ventricular ejection fraction (LVEF) (OR, 0.96 per 1% increase; 95% CI, 0.94-0.9; p = 0.009). DRT and SSE both occurred in 17 of 65 patients (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 left atrial appendage closure (LAAC), most SSEs (123 of 142, 86.62%) occurred in patients without DRT.
Conclusions:
The authors concluded that DRT (~3.7%) is not frequent after LAAC with Watchman, but when present, is associated with a higher rate of stroke and SSE.
Perspective:
This study reports that DRT occurs in ~3.7% of patients following LAAC with the Watchman device and is associated with higher rates of all-cause stroke/SSE and ischemic stroke/SSE. Patients with permanent atrial fibrillation, history of TIA/stroke, vascular disease, larger LAA diameters, and lower LVEF were more prone to develop DRT. Given the implications of DRT, a judicious surveillance strategy using periodic TEE should be considered, particularly when risk factors for DRT are present. Furthermore, anticoagulation should promptly be resumed when DRT is detected to potentially decrease the risk of subsequent ischemic stroke, with the caveat that patients choosing LAAC therapy are typically not good candidates for long-term anticoagulation.
Keywords: Anticoagulants, Arrhythmias, Cardiac, Atrial Appendage, Atrial Fibrillation, Brain Ischemia, Diagnostic Imaging, Echocardiography, Transesophageal, Embolism, Ischemic Attack, Transient, Primary Prevention, Risk Factors, Stroke, Stroke Volume, Thrombosis, Vascular Diseases
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