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Updated: Mar 24, 2026
The WATCHMAN Left Atrial Appendage Closure Device for Atrial Fibrillation
Published on: February 28, 2012
Assessment of Device-Related Thrombus and Associated Clinical Outcomes With the WATCHMAN Left Atrial Appendage
Michael L Main1, Dali Fan2, Vivek Y Reddy3
1Saint Luke's Mid America Heart Institute, Kansas City, Missouri.
Insights
Left atrial appendage closure device-related thrombus (DRT) was identified in 5.7% of patients. Clinical events occurred at 3.4 per 100 patient-years, highlighting DRT as a critical factor in atrial fibrillation stroke prevention.
Area of Science:
- Cardiology
- Medical Imaging
- Interventional Cardiology
Background:
- Left atrial appendage closure (LAAC) with the WATCHMAN device offers an alternative to anticoagulation for stroke prevention in atrial fibrillation (AF) patients.
- Device-related thrombus (DRT) formation after LAAC is not well-defined, impacting patient management and stroke risk assessment.
Purpose of the Study:
- To establish consensus echocardiographic criteria for diagnosing DRT.
- To determine the incidence of DRT following LAAC.
- To evaluate clinical event rates in patients diagnosed with DRT.
Main Methods:
- Development of a training manual and consensus criteria for DRT diagnosis by experienced echocardiographers.
- Review of transesophageal echocardiography (TEE) studies from the PROTECT-AF trial.
- Multi-phase reading process including independent scoring and group adjudication to identify DRT.
Main Results:
- Consensus diagnostic criteria for DRT were established.
- DRT was identified in at least one TEE in 27 out of 485 (5.7%) patients in the PROTECT-AF trial.
- Clinical events (stroke, embolism, death) occurred in DRT patients at a rate of 3.4 per 100 patient-years.
Conclusions:
- DRT incidence following WATCHMAN implantation is approximately 5.7%.
- The clinical event rate in patients with DRT is intermediate compared to overall device and warfarin arms in the PROTECT-AF trial.
- Standardized echocardiographic criteria are crucial for accurate DRT diagnosis and risk stratification in LAAC patients.
Abstract:
Left atrial appendage closure with the WATCHMAN device is an alternative to anticoagulation for stroke prevention in selected patients with atrial fibrillation (AF). LA device-related thrombus (DRT) is poorly defined and understood. We aimed to (1) develop consensus echocardiographic diagnostic criteria for DRT; (2) estimate the incidence of DRT; and (3) determine clinical event rates in patients with DRT. In phase 1 (training), a training manual was developed and reviewed by 3 echocardiographers with left atrial appendage closure device experience. All available transesophageal (TEE) studies in the WATCHMAN left atrial appendage system for embolic protection in patients with atrial fibrillation (PROTECT-AF) trial patients with suspected DRT were reviewed in 2 subsequent phases. In phase 2 (primary blind read), each reviewer independently scored each study for DRT, and final echo criteria were developed. Unanimously scored studies were considered adjudicated, whereas all others were reevaluated by all reviewers in phase 3 (group adjudication read). DRT was suspected in 35 of 485 patients by the site investigator, the echocardiography core laboratory, or both; 93 of the individual TEE studies were available for review. In phase 2, 3 readers agreed on 67 (72%) of time points. Based on phases 1 and 2, 5 DRT criteria were developed. In phase 3, studies without agreement in phase 2 were adjudicated using these criteria. Overall, at least 1 TEE was DRT positive in 27 (5.7%) PROTECT-AF patients. Stroke, peripheral embolism, or cardiac/unexplained death occurred in subjects with DRT at a rate of 3.4 per 100 patient-years follow-up. In conclusion, DRT were identified on at least 1 TEE in 27 PROTECT-AF patients, indicating a DRT incidence of 5.7%. Primary efficacy events in patients with DRT occurred at a rate of 3.4 per 100 patient-years follow-up, intermediate in frequency between event rates previously reported for the overall device and warfarin arms in PROTECT-AF.
