DISCUSSION:
The main findings of our current investigation are: (1) Over the study
period from 2015-2017, there has been a significant increase in the
number of Watchman device implantation procedures in the United States
(from 1,195 in year 2015 to 11,165 devices in year 2017, p <
0.01). (2) There has been a decline in the rate of complications over
the study period primarily driven by lower rates of cardiovascular and
neurological complications. (3) Overall mortality continues to be low
during the study period, with an even lower trend towards reduced
mortality over the study years (1.3% in year 2015 vs. 0.1% in year
2017, p < 0.01). (4) The total length of stay and
hospitalization costs after Watchman implantation declined over the
study period.
Percutaneous LAAO with the Watchman device provides a viable alternative
to oral anticoagulation in select patients based on randomized trials
that have shown efficacy and safety of utilizing this approach for
stroke risk reduction (10,11). The FDA approved the device for
commercial use in United States in March of 2015 and the Watchman
implant procedure currently carries a class IIb recommendation in
patients with non-valvular AF at risk for stroke per the latest American
College of Cardiology guidelines (14). Our analysis of a contemporary,
real-world, national database sampling US practice since FDA approval of
Watchman showed consistent increased utilization of device procedures
suggesting gradual assimilation of this device implantation procedure in
clinical practice. Additionally, our analysis also showed that
complications and in-patient mortality associated with implantation of
Watchman devices continued to show a downward trend.
Our study showed a significant decline in the overall complication rate
over the study period (26.4% in year 2015 vs. 7.9% in year 2017, p
< 0.01). This downtrend was primarily driven by a reduction in
cardiovascular and neurological complications over the study period.
Cardiac perforation complications including cardiac tamponade were
encountered in the landmark PROTECT trial where its prevalence was
approximately 4.3% (10). Subsequently, with improved operator
experience and better implant techniques, the incidence of this
complication was lowered to 1.9% in the PREVAIL trial, 1.4% in CAP
(Continued Access to PROTECT), 1.9% in CAP2 (Continued Access to
PREVAIL), and 0.3% in EWOLUTION registries (11,15,16). The overall rate
of cardiac tamponade in the current study of contemporary Watchman
patients was 0.8%. This rate is similar to post-FDA approval study led
by Reddy et al. in which the authors reported a nearly similar rate of
cardiac tamponade at 1%; still higher than the European EWOLUTION
registry which reported cardiac tamponade rate of 0.3% (17). It is also
similar to a recently published contemporary registry of Watchman
implantations from National Cardiovascular Data Registry which analyzed
nearly 38,000 patients (18). It may be expected that with more
widespread availability of the Watchman device in US practice that the
rate of cardiac tamponade may continue to decline over the coming years.
The rate of ischemic stroke/transient ischemic attack (TIA) was 1% in
our study cohort with most cases reported in 2015 and a significant
downtrend since that time (0.7% in year 2016 and 0.4% in year 2017, p
< 0.01). Vuddanda et al. have shown nearly similar ischemic
stroke/TIA rates of about 0.5% when analyzing Watchman implants from
year 2016 (13). These strokes are presumed to be due to inadvertent air
or clot embolization from the trans-septal sheath and enhanced physician
training should continue to mitigate this risk.
The current study showed a downward trend in in-hospital mortality
suggesting improved safety with the device with more operator experience
(from 1.3% in year 2015 to 0.1% in year 2017, p < 0.01).
Improvement in mortality rate trends over time seen in the current study
of real-world patients was also seen in previous clinical studies,
including the CAP2 registry which supplemented the PREVAIL trial and was
designed to continue long-term accrual of data, and showed a mortality
rate of 0.2% within 7 days of Watchman implant (15). A subsequent study
utilizing National Inpatient Sample database by Vuddanda showed a
mortality rate of 0.3% at discharge for combined endocardial and
epicardial based approaches for LAA occlusion (13). In another post-FDA
approval analysis of more than 3,800 patients undergoing Watchman
implantation from March, 2015 to May, 2016, Reddy et al. demonstrated
procedure related mortality of 0.078% (17). The prospective EWOLUTION
registry that enrolled more than 1,000 consecutive patients undergoing
Watchman implantation outside the US also showed low procedure related
mortality of 0.1% (16). These earlier studies along with our more
contemporary data suggest that overall implantation of the Watchman
device is associated with low absolute rates of mortality that is
decreasing over time.