Intracardiac Echo a Good Imaging Option to Guide LAA Closure

Intracardiac echocardiography can be used to safely and effectively guide left atrial appendage occlusion (LAAO) with the Watchman FLX device (Boston Scientific), according to the results of multicenter study.

The investigators, led by Jens Erik Nielsen-Kudsk, MD, DMSc (Aarhus University Hospital, Denmark), believe these data show that intracardiac echocardiography (ICE) is a valid alternative to transesophageal echocardiography (TEE) and can help simplify the LAAO workflow.

“The most frequently used imaging for Watchman FLX implants and other LAA implants is transesophageal echo,” Nielsen-Kudsk told TCTMD. “In most centers, that would require general anesthesia and tracheal intubation. You need the anesthesiology team and a dedicated cardiologist to do the transesophageal echo. It’s quite a demanding setup. The drawback is also that general anesthesia comes with its own risks. Patients undergoing left atrial appendage closure are often elderly and fragile—they might not tolerate general anesthesia so well.”

Intraprocedural imaging with ICE has emerged as alternative to TEE, with the advantage being use of local anesthesia with an awake and cooperative patient. “You also don’t need the anesthesiology team and a separate cardiologist to do the TEE during the procedure,” said Nielsen-Kudsk. “The turnover time for the procedure is much faster with this concept.”

Andrew Goldsweig, MD (Baystate Medical Center, Springfield, MA), who wasn’t involved in the study, said they almost entirely use ICE to guide LAAO at his center, adding that they recently switched from 2D ICE to a 3D ICE catheter. He noted that all of the pivotal trials for LAAO used TEE to guide the procedure, but interest in and greater uptake of ICE were sparked by the COVID-19 pandemic.

“First, nobody wanted to be near other people’s respiratory tract, and second, hospital administrators were telling us, ‘Look, we want these procedures, but we don’t have any inpatient beds—you have to do same-day discharge—and we don’t have any anesthesiologists, so you have to them awake,’” Goldsweig told TCTMD. “If you do [LAAO] with ICE, patients are awake, there’s no intubation/extubation, you can discharge them the same day, and you don’t need an anesthesiologist.”

For Goldsweig, ICE “is a win for everybody involved,” but acknowledged that with 2D ICE, the imaging can be more limited, although it can be augmented with fluoroscopy. “As far as I’m concerned, ICE is very rapidly becoming the standard of care for left atrial appendage occlusion,” he said.

The ICE LAA Study

To demonstrate that ICE is a valid alternative to TEE, Nielsen-Kudsk and colleagues launched ICE LAA, a prospective, single-arm, multicenter study. The study, which was published this week in JACC: Cardiovascular Interventions, included 100 patients (mean age 76 years; 33% female) with nonvalvular atrial fibrillation and a CHA₂DS₂-VASc score ≥ 2 (mean score 4.0) who were undergoing Watchman FLX implantation at seven European centers. All patients underwent preprocedural imaging with cardiac CT (or 3D TEE if CT was not available) to assess the appendage anatomy, predict device sizing, and exclude LAA thrombus.        

The primary endpoint—the rate of peridevice leak > 5 mm at 45 days on TEE assessed by an independent echocardiography core lab—was not seen in any patients. In terms of procedural outcomes, device and technical success rates were 100%. Procedural success was 96%, with two patients having access-site bleeding and groin hematoma. No cases required conversion to TEE during the implantation, while the median procedure and fluoroscopy times were 50.5 and 17.8 minutes, respectively.

The researchers compared 45-day outcomes with patients treated in the PINNACLE FLX trial, a study of patients implanted with Watchman FLX using TEE guidance. Overall, results were similar, with no differences in mortality, stroke, systemic embolism, major bleeding, pericardial effusion, or device embolization seen between the two imaging strategies. In ICE LAA, one patient died of cardiac arrest 10 days after an uncomplicated Watchman implantation.

To TCTMD, Nielsen-Kudsk said they have used ICE for LAAO, both with Watchman and other LAA occlusion devices, for many years at their hospital. In 2020, his group published early results showing that ICE could be used to safely and effectively guide Watchman FLX implantations. The ICE LAA study differs in that peridevice leak was adjudicated by an independent core laboratory and more centers were involved. “We wanted to show that other operators could reproduce the procedure and have the same good results with this type of image guidance,” he said. “Of course, you have to realize there is a learning curve for maneuvering the ICE probe.”

Most electrophysiologists, he said, have a good handle on ICE because it’s used for all transseptal punctures. Operators with experience in patent foramen ovale (PFO) and atrial septal defect (ASD) closures will also be comfortable with using ICE.

One of the drawbacks of switching from TEE is the cost of the ICE catheter. However, Nielsen-Kudsk said the switch eliminates the anesthesiology team and TEE operator, and with the streamlined workflow, centers will be able to do more cases per day. For this reason, he believes ICE-guided LAAO would be “cost neutral” when compared with conventional imaging.

The ICE catheters used in the present analysis were 2D and the imaging is not precise enough to provide accurate sizing of the Watchman FLX. For that reason, Nielsen-Kudsk stressed the importance of 3D preprocedural imaging. With ICE-guided Watchman implantations, they also used the PASS criteria (position, anchoring, sizing, and sealing), which is performed with four standard views on TEE, to assess whether the LAAO is optimized.

“So, this is also a demonstration that the PASS criteria can be fulfilled using intracardiac echocardiography,” he said.

As in the present study, Goldsweig said they’ve also achieved excellent outcomes with ICE at his center, adding that they began using it around the time the next-generation Watchman FLX came to market. With a better device and improved operator skills gained through experience, their results today are even better today than when using TEE.

There is a learning curve, he said, but there’s a wide range in comfort with ICE in cardiovascular medicine. Today, there are three US Food and Drug Administration-approved 3D ICE catheters on the market—VeriSight Pro (Philips), Ultra ICE (Boston Scientific), and AcuNav Volume (Siemens)—and these devices offer advantages over 2D catheters, although they are more expensive.

In terms of preprocedural planning, Goldsweig said 2D ICE is not as good as TEE for ruling out thrombus in the LAA, which is a contraindication for closure. CT prior to the procedure is helpful for defining the anatomy and ruling out thrombus, but 3D ICE does provide excellent imaging for procedural planning. He noted that when he practiced at the University of Nebraska Medical Center, some patients traveled long distances for LAAO.

“We’d have patients coming from 6 or 7 hours away,” he said. “They can’t come in for CT and then come back the next week for the procedure. Here, 3D is a big game changer because you can visualize any part of any appendage with 3D ICE.”  

Learning Curve and Cost

In an editorial, Mohamad Alkhouli, MD (Mayo Clinic, Rochester, MN), says that changing practices in interventional cardiology requires a solid rationale, supportive safety and effectiveness data, a reasonable learning curve, and sound economics. The ICE LAA study has some limitations—modest sample size, lack of a direct control arm, and loss to follow-up (approximately 15%)—but provides a “simple and validated ICE imaging protocol than can be used in clinical practice and in future studies to address remaining open questions surrounding ICE-guided LAA closure,” he notes.

Alkhouli, whose center switched to ICE-guided LAAO in 2016, says there’s ample evidence that ICE is safe, but the efficacy data are less certain because many studies are self-reported and don’t directly compare ICE with TEE. There are data showing an association with peridevice leak and subsequent ischemic events, so achieving complete closure is critical, which makes some physicians skeptical about abandoning TEE. The learning curve is a worry, as is the cost of the ICE catheters.

“Despite these persistent concerns, the ICE LAA study remains very valuable as it provides simple validated ICE PASS criteria, which can be used clinically and in subsequent research,” he writes. “It may also clear the way for a change in the label of the Watchman FLX device, in which the use of ICE is currently considered off-label.”