Discussion
Analysis of 30-day all-cause readmissions after the LAAC procedure
revealed several important findings. First of all, 8.2% of patients who
received the LAAC device were readmitted within 30 days. Independent
predictors of readmission included non-routine disposition such as
discharge to Home Health Care (HHC) or a SNF, chronic pulmonary
disease, renal disease, and anemia.
Both cardiac and non-cardiac causes accounted for readmission, with
atrial arrhythmias and congestive heart failure being the most common.
Charges varied significantly between readmitted and non-readmitted
patients on index admissions. The readmission rates of LAAC procedures
seem to be lower when compared with those of other cardiac procedures
and diseases, including readmissions for congestive heart
failure, TAVR, or PCI15–17. This may reflect the fact
that procedural success has increased since FDA approval, while
complication rates have decreased8. Interestingly,
neither hospital procedural volume nor peri-procedural complications
correlated significantly with readmission rate, save for peri-procedural
acute renal failure and venous thromboembolism, though this may be a
function of the low number of reported complication rates (Table 3).
Since 30-day readmissions are viewed as a quality performance measure,
this study is an important one in identifying patients at risk for
readmission and directing resources towards them. Our results suggest
that patients with kidney disease, COPD, CHF, ischemic heart disease,
and anemia are at elevated risk for readmission within 30 days.
Interestingly, though the readmission rate for LAAC devices was lower
than in TAVR, the predictors for readmission are strikingly similar,
likely reflecting the fact that patients with greater disease burden in
general are at elevated risk of readmission16. Our
multivariable model had modest discriminatory ability in predicting
these readmission (ROC 0.70), which is on par or better than many
rehospitalization prediction models18.
These predictors of readmission reflect the fact that patients with
increased comorbidities are at higher risk of readmission. Patients who
are discharged to HHC or SNF often require greater care, have a greater
number of comorbidities, incur higher inpatient charges, and are
generally frailer than patients who are discharged home—a common
pattern among post-surgical, acute care, trauma, stroke, post-cardiac
surgery, and heart failure patients19–23. Medicare
data examining characteristics predisposing SNF residents to readmission
found that ~21% of residents had been readmitted within
30 days, with a significant percentage of residents presenting with an
admission diagnosis of cardiac conditions 24,25.
Therefore, it is not surprising that these patients are more likely to
be readmitted after receiving a LAAC device.
Anemia is an especially common comorbidity encountered in LAAC patients,
as the primary criterion for LAAC selection is the desire to avoid
indefinite anticoagulation, generally due to
bleeding risk26. Current guidelines recommend that
patients who undergo WATCHMAN continue on anticoagulation for at least
45 days5. Speculatively, it is possible that patients
who are anemic during their index hospitalization may be anemic because
of an increased predisposition towards bleeding and would have greater
difficulties tolerating post-procedural anticoagulation, leading to
increased readmission. Further study regarding the possible utility of
post-procedural hemoglobin monitoring or alternative post-procedural
anticoagulation strategies is warranted.
Major causes of readmissions included arrhythmia (atrial fibrillation
and flutter), heart failure, gastrointestinal disease, and sepsis.
Readmissions for cerebral infarction made up only 1.63% of readmissions
(n=3). One of the major causes of rehospitalization is congestive heart
failure, and numerous studies are underway to investigate strategies to
aid in reducing overall readmissions for heart
failure27,28. Interestingly, however, neither
congestive heart failure nor cardiomyopathy during the index admission
were predictive of readmissions on multivariate analysis. This
discrepancy may reflect hemodynamic changes caused by LAA occlusion
itself. In animal studies, occlusion of the left atrial appendage
results in increases in left atrial filling pressures, which results in
diastolic dysfunction29. One single center study
reported increases in mitral E/E’ ratios three months after left atrial
occlusion on echocardiography, indicative of increases in left- sided
filling pressures.30 Further study is needed in this
area.
Interestingly, gastrointestinal disease was not an independent risk
factor for readmission but was a top cause of readmission. The
subcategories of the general ICD-10 code for gastrointestinal disease
include hematemesis, melena, hemorrhage, mucositis, and unspecified.
Therefore, the gastrointestinal disease code likely captured many
patients with bleeding complications after LAAC. While gastrointestinal
disease was not an independent risk factor for readmission, anemia was
an independent risk factor. Patients who undergo LAAC usually have
contraindications to anticoagulation, and therefore the required 45 days
of anticoagulation afterwards may predispose to bleeding complications,
particularly gastrointestinal bleeding.
Further studies examining anticoagulation strategies after WATCHMAN are
needed, given the significant portion of readmissions post-WATCHMAN
implantation that are related to gastrointestinal hemorrhage.
Atrial fibrillation and atrial flutter as causes of readmission may
reflect the arrhythmic burden in patients who receive the procedure, as
all patients who receive the device have atrial fibrillation. When
compared with 30-day readmission rates in patients who are admitted for
atrial fibrillation, readmissions for atrial fibrillation after LAAC
appear lower. A 2017 study of 388,340 patients admitted for atrial
fibrillation and subsequent 30-day readmissions found that atrial
fibrillation was the most common readmission diagnosis and accounted for
27.1% of readmissions, followed by heart failure, accounting for
11.4%. In contrast, in the current study, only 8.23% of readmissions
after LAAC were due to atrial fibrillation, and 8.23% of readmissions
were secondary to CHF 31.
The average length of stay during index admission for readmitted
patients was nearly twice the length of stay for non-readmitted patients
(2.8 days versus 1.5 days). This difference may explain the discrepancy
in accrued charges observed between both groups ($139,869 versus
$115,258).
Unfortunately, given the constraints of the NRD, it was not possible to
elucidate the reason for the prolonged stay during the index
readmission. To our knowledge, there is no standardized guideline for
length of stay for LAAC procedures. This is considerably less than the
average length of stay for TAVR, percutaneous ASD closure, and
transcatheter mitral valve repair, which are all reported to be greater
than 5 days based on analysis of national
databases32–35.
Given the relative lack of medical guidelines for defining an
appropriate length of stay post LAAC, further investigation may be
warranted. Standardization of post-LAAC length of stay will result in
significant charge savings, given that the average charge of the
readmitted hospital stay was nearly 50% of the cost of the index
admission ($62,577). Similar efforts are underway for elective
percutaneous coronary intervention (PCI), as evidenced by a recent study
highlighting roughly $5,000 worth of savings from employing a same-day
discharge strategy, rather than one involving overnight stay, without a
corresponding increase in adverse events36.
The role of 30-day readmissions as a quality performance measure
underscores the importance of this analysis as a vital first step in
elucidating risk factors for readmission after the LAAC procedure.
Recent data suggest that quality of life improves after the WATCHMAN
procedure, when compared with quality of life of patients reliant on
lifelong warfarin37. Atrial fibrillation diagnoses are
expected to double by 2050, and it is likely that left atrial appendage
occlusion will continue to gain favor as a method of stroke prevention,
due to decreasing rates of periprocedural complications, overall safety,
and patient preference1,38. The results of this study
will be useful in identifying patients at high-risk of 30-day
readmission after LAAC and developing strategies to lower readmission
rates.
Readmission scoring systems are of particular interest since CMS
implemented the Hospital Readmissions Reduction Program (HRRP), and
robust models are scarce. Mortality models fare reasonably well, but
readmissions models are less discriminatory with an average c statistic
of 0.6339. The CMS-endorsed Readmission Risk Score
(RRS), a composite of 37 variables, has a c statistic of 0.6 for 30 day
all-cause readmissions for CHF40. Similarly, the
HOSPITAL score, designed to predict avoidable all-cause 30 day
readmission, has a c statistic of 0.7141. Countless
additional scores exist, and there is considerable overlap between
variables used in mortality scores with high predictive ability and
readmissions scores that do not fare as well.
Our readmission scoring system had modest discriminatory ability with a
C-statistic of 0.67 in derivation and 0.63 in validation. Our scoring
system is on par with most readmission models and may be more clinically
useful given its simplicity. We suggest designating patients with a
score of 1 or less as “low” risk, 2 to 3 as “moderate” risk, and 4
and above as “high” risk.This may aid clinicians in risk stratifying
patients at greater risk for being readmitted post-LAAC
Limitations
There are few limitations to this study. This analysis is based solely
on diagnostic and administrative variables, and there is a noted absence
of procedural or detailed clinical data. Details on LAAC device size,
type, echocardiographic variables, such as LAA dimensions and
the degree of para-device leak, were not available. Additionally, the
cause of readmission was elucidated through discharge diagnosis codes,
an approach that is utilized extensively in 30-day readmissions
analyses. Furthermore, the NRD does not contain data on patients who are
readmitted to a hospital in another state, which may result in an
underestimation of the true readmission rate. For the scoring system,
ICD9 and ICD10 codes are not 1:1, so potential data points may have been
either not counted for or incorrectly included. Efforts were made to
minimize this. Finally, the NRD does not track mortality, and so the
influence of mortality on the rates of readmission cannot be accounted
for.