Boston Scientific heart implant linked to steep drop-off in afib-related stroke risk: study

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The Watchman FLX device is implanted inside the opening of the heart’s left atrial appendage to block blood from pooling there and forming potentially dangerous clots, therefore reducing the risk of stroke and systemic embolism in patients with non-valvular atrial fibrillation. (Boston Scientific)

The idea of implanting a device inside the heart to block blood flow may sound counterintuitive, but in the case of left atrial appendage closure devices like Boston Scientific’s Watchman FLX, that intentional blockage could save lives.

The Watchman device is designed for use in patients with atrial fibrillation not caused by problems with a heart valve, as an alternative to long-term use of blood thinner medications like warfarin.

The cylindrical device is implanted in the opening of the left atrial appendage, a small pouch on the muscle wall of the heart’s upper left chamber. Though scientists are still unsure of the appendage’s exact function, in patients with afib, blood sometimes pools in the pouch and forms clots, which are then pumped out of the heart, potentially causing a stroke or systemic embolism.

By blocking the opening of the appendage, the Watchman FLX prevents those blood clots from forming. Newly released clinical trial data shows that, in fact, in the two years after implantation, patients using the Watchman device experienced ischemic stroke or systemic embolism at a rate of just 3.4%.

That’s well below the study’s secondary effectiveness endpoint, which deemed the Watchman system successful if the two-year stroke and embolism rate maxed out at 8.7%.

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The two-year data also found that none of the 400 U.S. patients studied in the trial experienced a device embolization or pericardial effusion—both of which would require invasive heart surgeries to correct—after the device was implanted.

The new results of the Pinnacle FLX trial were released exactly a year after the Watchman FLX was approved by the FDA for use in reducing stroke risk in afib patients in need of an alternative to long-term oral anticoagulation therapy.

Initial study results presented earlier this year at the annual scientific sessions of the American College of Cardiology saw the Watchman FLX achieve all of its primary safety and efficacy endpoints with flying colors.

In the safety category, only two of the 400 patients—representing 0.5% of the group—experienced adverse events within seven days of the procedure. Meanwhile, the device was proven to successfully block blood flow to the left atrial appendage in 100% of patients, and to maintain that blockage at 45 days and one year after the implantation.

At the time, the researchers also noted that the implant led to stroke rates about 77% lower than the average for high-risk afib patients.

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Taken all together, the Pinnacle FLX trial’s results are “very encouraging” for the device’s core audience, which is made up largely of elderly patients with complex cardiac conditions that place them at a higher risk for strokes while taking oral blood thinners, according to Saibal Kar, co-principal investigator of the study.

With the Watchman FLX’s safety and efficacy thoroughly proven, Boston Scientific will now shift its focus to a handful of other ongoing studies of the device.

One of these, the Option trial, is comparing the performance of the device to that of oral anticoagulants in patients with atrial fibrillation who have also undergone a cardiac ablation procedure. Another, named Champion-AF, will study the device’s ability to prevent embolic stroke in an even larger patient population.