What Is the Success Rate of the Watchman Procedure?

The Watchman procedure succeeds in placing the device correctly in roughly 95% to 99% of attempts, depending on which generation of the device is used and how experienced the implanting team is. The largest U.S. registry, covering more than 97,000 patients, reports a successful implantation rate of 97.5% with the current-generation Watchman FLX. That number reflects everyday clinical practice rather than cherry-picked trial conditions, which makes it a reliable benchmark for anyone considering the procedure. But “success” has layers beyond whether the device lands in the right spot, and the details matter more than the headline figure.

What the Registry Data Actually Show

The most robust picture of real-world Watchman performance comes from the NCDR Left Atrial Appendage Occlusion Registry, a national database that tracks outcomes across hundreds of U.S. hospitals. Among 97,185 patients who received the Watchman FLX, successful implantation occurred in 97.5% of cases.¹ That figure accounts for all comers, including patients with tricky anatomy or higher surgical risk.

Smaller, more controlled studies have reported even higher numbers. The FLXibility Post-Approval Study, which tracked 300 patients across European and U.S. centers, found a 99.0% procedural success rate. The three failures in that study were due to unfavorable anatomy or a device positioned too far forward to meet release criteria.² The earlier EWOLUTION registry, which enrolled over a thousand patients across 47 centers, reported 98.5% successful deployment.³

The gap between the large registry number and these smaller studies probably reflects the real-world messiness that a national database captures. Lower-volume hospitals and newer operators contribute to the registry, pulling the average down slightly. In experienced hands, the procedure fails to place the device only about 1% to 2% of the time.

The Newer FLX Device Changed the Numbers

If you are researching the Watchman now, you are almost certainly looking at the FLX model, which replaced the original Watchman 2.5 in 2020. The redesign was meaningful. A systematic review and meta-analysis pooling over 54,000 patients found the FLX had roughly seven times the odds of procedural success compared with the original device.⁴ That same analysis found the FLX was associated with substantially lower rates of mortality, major bleeding, device embolization (the device dislodging and migrating), and pericardial effusion (fluid collecting around the heart).

Data from the Japanese OCEAN-LAAC registry confirm the pattern. The FLX succeeded in about 96% of cases compared with roughly 92% for the Watchman 2.5, a statistically meaningful gap driven primarily by fewer pericardial effusion events with the newer design.⁵ The FLX also showed a significantly lower rate of peri-device leak at the 45-day follow-up imaging check (about 15% versus 24% for the older model) and lower one-year rates of ischemic stroke and major adverse events.⁶

The FLX’s shorter profile and improved ability to be recaptured and repositioned during the procedure made it possible to treat patients whose anatomy previously disqualified them, particularly those with a “chicken-wing” shaped appendage or a shallow appendage.⁷ So if you encounter older success-rate data from before 2020, keep in mind those numbers reflect a device that is no longer used.

Complications That Happen Around the Procedure

Implantation success and complication-free implantation are not the same thing. A device can be placed correctly while the patient still experiences a procedure-related problem. The most common serious complication is pericardial effusion. Across the NCDR registry’s first 65,000-plus cases, it occurred in about 1.35% of patients.⁸ A separate analysis of roughly 17,700 U.S. procedures found a similar rate of about 1.24% for effusions that required intervention, but noted that those cases were associated with dramatically longer hospital stays and higher costs.⁹

Procedural stroke is another concern. Across multiple studies, the stroke rate during or shortly after the procedure sits around 1%.¹⁰ These rates have improved over time. Early data from the landmark PROTECT AF trial and its Continued Access Registry showed overall safety-event rates within seven days dropping from about 7.7% to 3.7% as operators gained experience, with serious pericardial effusions declining from 5.0% to 2.2%.¹¹ Today’s complication rates with the FLX are lower still, reflecting both the device redesign and a decade of accumulated procedural skill across the field.

Device-Related Thrombus and Peri-Device Leaks

Even after a technically successful implant, two issues can undermine the device’s protective benefit over time. The first is device-related thrombus, essentially a blood clot forming on the surface of the device itself. A pooled analysis of nearly 1,740 patients followed for several years found this occurred in about 3.7% of cases. When it did happen, the risk of stroke or systemic embolism roughly tripled compared with patients who did not develop a clot on the device.¹² This is why follow-up imaging and short-term blood-thinning medications after implantation are standard practice.

The second issue is peri-device leak, meaning blood can still flow around the edges of the device into the appendage. Small leaks (5 mm or less) are common. In one analysis of over 51,000 patients from the NCDR registry, about a quarter had a small leak and under 1% had a large one. Small leaks were linked to modestly higher rates of stroke, blood clots, and bleeding. Large leaks, counterintuitively, were not associated with worse outcomes, though many of those patients were kept on blood thinners, which likely offset the risk.¹³

Timing of follow-up imaging matters. One study tracking patients over five years found that a small leak detected at the one-year follow-up, but not at the initial 45-day check, was associated with roughly double the risk of ischemic stroke or systemic embolism.¹⁴ Japanese registry data has also found that even leaks of 3 mm or less carry a significantly elevated risk of stroke-related events compared with a complete seal.¹⁵ These findings reinforce why the procedure’s success is best judged not just by whether the device deploys, but by whether follow-up imaging confirms a good seal over the months and years that follow.

How Much Your Doctor’s Experience Matters

Operator volume is one of the strongest predictors of a good outcome, and the effect is larger than many patients realize. A study of more than 87,000 patients across 693 U.S. hospitals found that the overall procedural success rate was 94.2%, but hospitals in the lowest volume quartile had about a third lower odds of success compared with the highest-volume hospitals. Physician-level volume showed a similar pattern, with low-volume operators consistently less likely to achieve a successful implant.¹⁶

Research has put a specific number on the experience threshold. An analysis using maximally selected log-rank statistics identified 32 procedures per year as the cutoff distinguishing experienced operators. Operators performing fewer than 32 annually had about 1.8 times the risk of adverse outcomes, and every additional five cases per year reduced that risk by roughly 12%.¹⁷ So asking your hospital or cardiologist how many procedures they perform each year is a reasonable and practical question.

How Watchman Compares to Blood Thinners

The Watchman was originally tested against warfarin, and it proved at least as effective for stroke prevention with the added advantage of reducing hemorrhagic stroke and major bleeding over the long term. A network meta-analysis found both the Watchman and newer oral anticoagulants (often called DOACs) were better than warfarin at preventing hemorrhagic stroke.¹⁸

The comparison with DOACs is more nuanced. One study looking at matched cohorts of about 2,250 patients per group found that by five years, the Watchman group had lower rates of major bleeding, transient ischemic attacks, and ischemic strokes compared with DOAC users.¹⁹ However, a different analysis found the Watchman had a somewhat higher relative risk of ischemic stroke compared with DOACs at both one and five years, while still showing a mortality advantage.²⁰ These seemingly contradictory results likely reflect differences in patient populations, matching methods, and follow-up periods. The evidence is strongest that the Watchman reduces bleeding risk relative to lifelong anticoagulation. Whether it matches or beats DOACs purely on stroke prevention remains an area of active debate.

The medication protocol after implantation also influences outcomes. For the first weeks to months following the procedure, patients typically take blood thinners anyway, usually a DOAC or warfarin, before transitioning to aspirin and then eventually stopping blood thinners altogether. A meta-analysis found that using a DOAC rather than warfarin during that post-implant period cut the risk of major bleeding roughly in half.²¹

Five-Year Outcomes and Who Gets the Procedure

Real-world long-term data from Medicare beneficiaries paints a sobering but clarifying picture. Among the typical Watchman population, which skews elderly and medically complex (the median stroke-risk score was 4 out of a possible 9, and about 42% had a history of major bleeding), five-year outcomes showed a 44% death rate, a 15% rate of major bleeding, and a 7% ischemic stroke rate.²² Those numbers reflect the fact that Watchman patients are, on average, sicker than the general atrial fibrillation population. They receive the device precisely because they cannot tolerate the blood thinners that would otherwise protect them, and they tend to have multiple serious health conditions. A 7% five-year stroke rate in this group is actually lower than what their risk scores would predict without any protection.

The most common reasons clinicians recommend the Watchman include a history of major bleeding, high fall risk, difficulty maintaining stable blood-thinner levels, and noncompliance with daily medication.²³ If you tolerate a DOAC well, without bleeding or side effects, a cardiologist is unlikely to recommend the Watchman as a first-line alternative. The device’s sweet spot is the patient for whom long-term anticoagulation is either dangerous or impractical.

Kidney Disease and Procedural Risk

Chronic kidney disease (CKD) is common among Watchman candidates and raises legitimate questions about safety. A single-center study of 300 patients found that CKD did not significantly affect the implantation success rate (about 99% versus 97% in CKD versus non-CKD patients). Stroke events and device-related thrombus occurred at similar rates in both groups, and the observed rate of clot-related events dropped by about 69% in CKD patients compared with what their risk scores predicted.²⁴

Larger database studies are less reassuring about complications, though. An analysis of over 36,000 procedures from the National Inpatient Sample found that CKD patients had higher rates of major complications (about 6.2% versus 5.1%), pericardial effusion requiring intervention (3.7% versus 2.7%), and pulmonary complications (5.1% versus 2.4%) compared with non-CKD patients.²⁵ CKD was also independently associated with longer hospital stays and higher costs. That said, another multi-center analysis found no statistically significant difference in mortality, length of stay, or periprocedural stroke between CKD and non-CKD patients.²⁶ The overall message is that the procedure can still be performed successfully in CKD patients, but the complication risk runs somewhat higher, and close monitoring is warranted.

The Watchman Versus Other Closure Devices

The Watchman is not the only left atrial appendage closure device on the market. The Amplatzer Amulet is its main competitor. A meta-analysis comparing the two found no meaningful differences in stroke prevention, systemic embolism, death, or major bleeding. However, the Amulet group had significantly lower rates of device-related thrombus and large peri-device leaks.²⁷ A sub-analysis from the LAARGE registry found similar patterns: technical success was slightly higher with the Amulet (99% versus 96%), procedural safety was comparable, and one-year outcomes were essentially the same.²⁸

A single-center head-to-head comparison, however, found the Amulet group actually had more periprocedural complications and more major bleeding events than the Watchman group, with similar long-term event rates.²⁹ The choice between devices often comes down to the patient’s specific anatomy and the operator’s experience with each system. Neither device has convincingly proven superior to the other in hard clinical outcomes.

Imaging During and After the Procedure

Watchman implantation traditionally relies on transesophageal echocardiography (TEE), which requires a probe placed down the throat, usually under general anesthesia. A growing number of centers now use intracardiac echocardiography (ICE), where the imaging probe enters through a vein along with the device. An analysis of over 25,000 patients found that ICE dramatically reduced the need for general anesthesia (about 54% of ICE patients received it compared with 98% of TEE patients) while producing equivalent device success rates and complete-seal rates at 45 days.³⁰ For patients concerned about general anesthesia, asking whether ICE guidance is available at their center is worth the conversation.

Cost Over Time

The Watchman carries a significant upfront cost, mostly from the device itself and the catheterization lab time. But because it replaces a lifetime of daily medication, cost-effectiveness analyses consistently show it pays for itself within several years. One model found that left atrial appendage closure became cost-saving compared with aspirin by about seven years and compared with the DOAC apixaban by about eight years, after which it continued to save money while providing more quality-adjusted life years.³¹ A separate analysis focused on patients who had already had a stroke found the Watchman became the dominant strategy (both cheaper and more effective) compared with warfarin and all four DOACs by the ten-year mark.³² These analyses matter most for younger patients or those expected to live long enough for the upfront investment to break even.