Safety and Feasibility of Intra-Cardiac Echocardiography in Guiding Left Atrial Appendage Occlusion With the Watchman Device: The ICE WATCHMAN Study
Phase: NA
Conditions: Left Atrial Appendage Occlusion
Sponsor: Mayo Clinic

Safety and Feasibility of Intra-
Cardiac Echocardiography in 
Guiding Left Atrial Appendage 
Occlusion with the Watchman 
Device:  
The ICE WATCHMAN study 
 
NCT# 05136417 
 
August 30, 2023 

 
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 Safety and Feasibility of Intra-Cardiac Echocardiography in Guiding 
Left Atrial Appendage Occlusion with the Watchman Device:  
The ICE WATCHMAN study 
Version 4 
08.30.2023 
 
 
1.0         PURPOSE OF THE INVESTIGATION              
 
The aim of this multi-center study will be to assess the feasibility and safety of left atrial appendage 
(LAA) occlusion with the WATCHMAN FLX™ device using a standardized intra-procedural 
intracardiac echocardiography (ICE) protocol under moderate sedation for procedural guidance. 
By eliminating the need for general anesthesia, we hope to show a reduction in procedural time, 
decrease use of supplemental invasive procedures (central venous line, invasive arterial pressure 
monitoring and transesophageal echocardiography) and quicker patient recovery time. This 
approach can decrease healthcare resource utilization and safely simplify left atrial appendage 
closure with the WATCHMAN device. 
 
2.0         CLINICAL PROTOCOL        
 
The study will be a prospective, non-randomized multicenter registry of 110 patients undergoing 
LAA closure with the WATCHMAN FLX utilizing an intra-procedural ICE probe under moderate 
sedation. The primary feasibility endpoint will be ability to successfully implant the 
WATCHMAN FLX device. Implant success is defined as confirmation of the device-specified 
release PASS (Position, Anchor, Size, Seal) criteria, successful device release, and adequate seal 
(defined as a residual leak <5 mm) as assessed by a core lab interpretation of the TEE (or CT) 45 
days post-implant. The primary safety endpoint will be a composite of major complications (major 
bleeding [intracranial bleeding, or bleeding requiring blood transfusion], pericardial effusion 
requiring pericardiocentesis or surgery, device embolization, procedural-related stroke, or 
procedural related death). Additional measured end points will be: freedom from conversion to 
general anesthesia and/or standard TEE during implant, the incidence and the size of iatrogenic 
atrial septal defect on 45 day TEE (or CT). The ICE procedural images will also be collected and 
analyzed by an independent committee composed of non-implanting interventionalist, and an 
imaging specialist. The images will be graded in quality as optimal (TEE equivalent), acceptable 
(adequate but not as detailed as TEE), and inadequate. This prospective study, along with its 
endpoints will be registered in clinicaltrials.gov  
 
2.1         SUBJECT SELECTION 
 
A total of 3 sites will enroll up to 110 consecutive patients, allowing room for 10 withdrawals to 
ensure data is collected on 100. 

 
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2.2      INCLUSION CRITERIA  
 
Determination for participation in the study is based on institutional standard of care practice for 
assessment of WATCHMAN FLX eligibility. Patients that are being considered for LAA Closure 
with WATCHMAN FLX device implant based on a history of non-valvular atrial fibrillation who 
are at increased risk for stroke and systemic embolism based on CHADS2VASc score >2 but have 
an appropriate rationale to seek a non-pharmacologic alternative to anti-thrombotic therapy due to 
risks of anti-thrombotic therapy. Patients should be able to tolerate the WATCHMAN FLX device 
implant procedure without the need for general anesthesia.    
 
Key inclusion criteria: 
• Men and Women > 18 years of age 
• The patients is eligible to undergo WATCHMAN FLX device implant procedure 
• The patient is eligible for short term anticoagulation therapy 
• Ability to tolerate the procedure without the need for general anesthesia as assessed by the 
treating physician(s) 
• Ability to give informed consent for the procedure 
• The patient is able and willing to undergo the procedure under moderate sedation 
• The patient is able and willing to return for required 45-day TEE or computed tomography 
(CT) scanning.  
 
2.3    EXCLUSION CRITERIA  
  
No specific exclusion criteria will be implemented based on age, weight, body habitus, renal 
insufficiency, LAA anatomy, or the presence of sleep apnea or chronic lung disease. However, 
Patients will be excluded from the study if the treating physician(s) feel that general anesthesia is 
necessary to safely complete the procedure.  
 
Key exclusion criteria: 
• Patient has contraindication for short term anticoagulation 
• The patient has history of a hypercoagulable state per medical record documentation 
• Pregnancy or planning to get pregnant during the investigation 
            
2.4    STUDY PROCEDURE 
 
Pre-Procedure: Informed consent should be obtained from the patient prior to the start of the 
procedure or within 48 hours post-WATCHMAN FLX procedure if ICE protocol is utilized. Pre-
procedural planning will be according to standard WATCHMAN FLX and local institution 
protocols. The use of cardiac CT is encouraged and should be performed shortly before the implant 
procedure (within 7-10 days) based on institutional protocols. Cardiac CT should be relied on as 

 
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the initial imaging modality to determine appendage anatomy, device sizing, and to exclude the 
presence of a LAA thrombus. In cases where CT scan cannot be performed prior to WATCHMAN 
FLX procedure, LAA thrombus will be excluded intraprocedural with ICE from the right atrium 
and/or pulmonary artery before transseptal puncture is completed. The treating cardiologist will 
screen the patient and deem them suitable for attempting the procedure with moderate sedation.  
 
Procedure: ICE will initially guide all implants. The ICE probe type (size, model, etc.), venous 
access approach (two vs. three venous accesses), access to the LA (single transseptal two probes 
or two different transseptal) are left to the discretion of the treating physician. However, the ICE 
probe will be advanced into the LA in all cases to guide the implant. It may not be possible to 
obtain identical views to those of TEE (0O, 45O, 90O, 135O) with ICE. However, two orthogonal 
(short axis and long axis) views of the LAA should be obtained with ICE to document the position, 
compression, leak, and record the tug test and comply with the device release criteria (ICE-PASS). 
The two recommended positions to obtain short- and long- axis views are mid- left atrium and left 
ventricular inflow view (just underneath the mitral valve) as illustrated in Figure-1. The 
WATCHMAN FLX device implant will otherwise be performed in accordance with standard 
practice, with the Boston Scientific clinical specialist overseeing the procedure. This individual is 
required to document appendage anatomy characteristics, procedural times, and release criteria 
measurements and device compression. The WATCHMAN FLX device should not be deployed 
unless all release criteria are met. Indications for conversion to general anesthesia are at the 
discretion of the treating physicians and include, but are not limited to, hemodynamic instability, 
inability to maintain a protected airway during the procedure, inadequate cardiac imaging with 
ICE, and patient discomfort.  
 
Post-Procedure: Patients should be monitored after the procedure according to institution specific 
protocol. Same day discharge for AM cases is allowed but not required. Patients should be 
maintained on a patient specific antithrombotic therapy for 45-day post-procedure based on the 
recommendation of the treating physician. Further anti-thrombotic changes should be made on a 
patient specific basis after consideration of the 45-day post-procedure TEE or CT scan and in 
accordance to WATCHMAN FLX device protocols. 
 
The study specific de-identified data collection form will be used to collect procedural data and 
information regarding the study’s primary and secondary endpoints for each case. A copy of this 
form, along with the pre-procedural CT imaging, procedural ICE images, and 45-day post 
procedure TEE or CT report should be compiled and sent to Mayo Clinic central repository 
database (Redcap) and Mayo Clinic Imaging Core Laboratory.  
 
 
 
 

 
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2.5     Study endpoints  
 
The primary feasibility endpoint will be ability to successfully implant the WATCHMAN FLX 
device. Implant success is defined as confirmation of the device-specified release criteria on ICE 
(ICE-PASS), successful device release, and adequate seal (defined as a residual leak <5 mm) 
assessed by TEE or CT scan at 45 days’ post-implant.  
 
The primary safety endpoint will be a composite endpoint of major complications (major bleeding 
and/or life-threatening [intracranial bleeding, or bleeding requiring blood transfusion], pericardial 
effusion requiring pericardiocentesis or surgery, device embolization, procedural-related stroke, 
or procedural related death). An event is defined as procedure related if it occurred during or within 
7 days of the procedure and deemed that the event was likely related to the device/procedure.  If 
the information is insufficient, the conservative position (assuming procedure related) should be 
taken. 
 
Secondary endpoints: These include freedom from conversion to general anesthesia and/or 
standard TEE during implant, incidence, and size of iatrogenic atrial septal defect at 45 days.  
 
2.5.1      Sample size determination            
The registry will enroll up to 110 patients, allowing room for 10 withdrawals to ensure data is 
collected on 100. 
 
2.5.2      Outcome data and data analysis  
Mayo Clinic Cardiovascular Imaging Core Laboratory will do data analysis.  
 
2.5.3      Data and Safety Monitoring Committee   
There will be no data and safety monitoring committee for this registry as the WATCHMAN FLX 
procedure is considered standard of care with either TEE or ICE at the participating institutions. 
Each site is expected to monitor appropriateness and outcomes of implant.  
 
3.0         RISK ANALYSIS    
Major procedural complications will be reported through the data collection form. However, 
since this is an observational registry that only collects clinical and imaging data from standard-
of-care routine procedures, adverse events will not be separately reported to the IRB.  
 
4.0      IRB INFORMATION      
Each site is responsible for its own institutional review board.  
 
5.0       ADDITIONAL RECORDS AND REPORTS       
 

 
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5.1       Data handling and record-keeping  
Each institution will be responsible for individual data handling and record keeping. A Data 
collection sheet will be used to record procedure related characteristics and track any 
complications. The site-specific primary investigator will be responsible for this form’s accuracy 
and completeness.  Data forms, CT, and TEE images should be de-identified and sent to the Mayo 
Clinic Laboratory from all participating institutions for data analysis.  
 
5.2       Record maintenance and retention           
Originals of all images, WATCHMAN FLX Implant Form, and data collection form will be 
maintained at each site. A copy of this information should be sent to the study primary investigator.