Large NCDR Registry Study Finds Leaks after LAAO Procedures Heighten Stroke Risk

April 3, 2022—The American College of Cardiology (ACC) announced that Mohamad Alkhouli, MD, presented findings demonstrating that patients who had leakage to the left atrial appendage because of incomplete device sealing after left atrial appendage occlusion (LAAO) experienced more clotting and bleeding events within 1 year after their procedure compared with patients who had no leakage.

The results suggest that even small leaks are associated with a 10% to 15% higher risk of adverse events, advised the ACC.

The ACC press release noted that the study included data from more than 50,000 patients in the National Cardiovascular Data Registry (NCDR) and is by far the largest to date to assess how leaking after LAAO affects the likelihood of adverse health outcome.

Dr. Alkhouli presented the study at ACC.22, the 71st annual scientific session of the ACC, which was held April 2-4 in Washington, DC. "Clinical Impact of Residual Leaks Following Left Atrial Appendage Occlusion: Insights From the NCDR LAAO Registry" was simultaneously published online by Dr. Alkhouli et al in JACC: Clinical Electrophysiology.

Dr. Alkhouli, MD, who is Professor of Medicine at Mayo Clinic in Rochester, Minnesota, commented in the ACC press release, "Our study shows that any leak matters, and we should find ways to optimize the procedure to minimize the proportion of patients who end up with leaks. Because this is a preventative procedure, it is important to find ways to master this and prevent leaks from happening. Fortunately, there are indications that leaking might be less common with newer devices and improved techniques."

The study was funded by Boston Scientific, maker of the Watchman LAAO device, which was approved by the FDA in 2015.

According to the ACC, the study investigators analyzed data from 51,333 patients who underwent LAAO procedures with the Watchman device between 2016 and 2019, as recorded in the ACC’s LAAO Registry (part of the NCDR databases), which includes approximately all LAAO procedures conducted in the United States.

Echocardiograms were used to classify the size of any leaks around the device an average of 45 days after a LAAO procedure. Registry data also included information about subsequent adverse health events occurring in the years after the procedure.

As summarized in the ACC press release, the investigators found the found:

• 73.4% of patients had no leaks; 25.8% had small leaks (> 0 mm but < 5 mm across); and 0.7% had large leaks (> 5 mm); these proportions are similar to those reported in previous registry studies and clinical trials.
• Although relatively few patients (approximately 2-3%) experienced adverse events in the year after an LAAO procedure, the investigators found that the relative risk of these events varied significantly between patients with and without leaks.
• Compared to patients who had no leaking, those patients with small leaks had a 10% higher relative risk of experiencing any major adverse events, an 11% higher relative risk of major bleeding complications, and a 15% higher relative risk of clotting-related events, including stroke, systemic embolization, and transient ischemic attacks.
• There was no significant difference in the rate of adverse events between patients with large leaks and those with small or no leaks. Dr. Alkhouli said that this finding is likely because of the use of anticoagulants in these patients. Instructions for the Watchman device indicate that patients who have residual leaks > 5 mm across should be considered to have a failed procedure, and they are generally treated with anticoagulants.

As reported in the ACC press release, Dr. Alkhouli observed that leaking is relatively common with LAAO procedures because the size and shape of the left atrial appendage varies widely from person to person, which can make it difficult for operators to position the device in a way that completely seals off the appendage. He noted that the shape of the appendage portion where the leaked blood flows into could affect the associated risks.

More recent technologies, such as the use of CT scans to image the appendage and software that allows users to practice the procedure virtually before operating on a patient, could help operators place the Watchman device in a more optimal position. Newer generation Watchman device designs, which were introduced in 2021, could also help to reduce the risk in some patients.

Finally, Dr. Alkhouli advised that the study was based on registry data reflecting real-world practices, so variations in the measurement of leaks could exist and may impact the results of the study. He added that future studies could help clarify whether using blood thinners in some patients with leaks < 5 mm would be helpful in reducing stroke risk.