Patients who had leakage to the left atrial appendage due to incomplete device sealing after left atrial appendage occlusion (LAAO) experienced more thromboembolic and bleeding events within a year following their procedure compared with patients who had no leaking, according to a Featured Clinical Research study presented April 3 at ACC.22 and simultaneously published in JACC: Clinical Electrophysiology. The study, which included data from more than 50,000 patients in ACC's LAAO Registry, is by far the largest to date to assess how leaking after LAAO affects the likelihood of adverse health outcomes.

For the study, researchers analyzed data from 51,333 patients who underwent LAAO procedures with the WATCHMAN device between 2016-2019 as recorded in ACC's LAAO Registry, part of the College's NCDR registries. 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.

Overall, researchers found that 73.4% of patients had no leaks, 25.8% had small leaks (greater than zero but less than 5 millimeters across) and 0.7% had large leaks (greater than 5 millimeters) – proportions similar to those reported in previous registry studies and clinical trials. While only about 2%-3% of patients experienced adverse events in the year following their LAAO procedure, the researchers found that the relative risk of these events varied significantly between patients with and without leaks.

Compared to patients who had no leaking, those with small leaks had a 10% higher relative risk of suffering any major adverse events, a 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. The study revealed no significant differences in the rate of adverse events between patients with large leaks and those with small or no leaks, which researchers said is likely due to the use of anticoagulants in these patients. Instructions for the WATCHMAN device indicate that patients who have residual leaks greater than 5 millimeters across should be considered to have a failed procedure, and they are generally treated with anticoagulants.

"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," said Mohamad Alkhouli, MD, FACC, professor of medicine at Mayo Clinic and the study's lead author. "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 [with improved seal] and improved techniques."

The study was based on registry data reflecting real-world practices, meaning variations in the measurement of leaks could exist and may impact the results of the study, Alkhouli said. He added that future studies could help clarify whether using blood thinners in some patients with leaks smaller than 5 millimeters would be helpful in reducing stroke risk.

Clinical Topics: Arrhythmias and Clinical EP, Atrial Fibrillation/Supraventricular Arrhythmias

Keywords: ACC Annual Scientific Session, ACC22, Atrial Fibrillation, Pyridones, National Cardiovascular Data Registries, LAAO Registry

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