Comment
Unmatched analysis in this study demonstrates an association between the
use of MAC for TAVR and reductions in OR time, ICU LOS, total LOS,
hospital cost, and total cost. However, MAC was also associated with
lower VASQIP estimated mortality (Table 1 ). This difference
reflects temporal trends in TAVR use. TAVR was initially applied only to
patients not considered surgical candidates as a salvage alternative to
medical therapy, then to high risk patients, and eventually to
intermediate and low risk patients in later years.2,
27, 30-32 MAC was not used for TAVR at this institution until 2015, and
as it became increasingly implemented, the use of GA declined
(Figure 2 ). This trend is consistent with national
trends.14 Given the asymmetrical temporal distribution
of surgical risk and anesthesia modalities with time, propensity
matching was necessary to reduce confounding bias and for meaningful
comparisons between anesthesia modalities for TAVR.
The incidence of adverse outcomes, including atrial fibrillation,
cardiac arrest, CVA, MI, and renal failure requiring renal replacement
therapy, were not significantly different between propensity-matched
groups of TAVR patients. The incidence of these events after TAVR is
known to be low, and this study was insufficiently powered to detect
differences in the occurrence of these uncommon
events.14 25, 29, 33 No significant differences were
found in 30-day mortality or the percentage of patients discharged
elsewhere besides home, but MAC was associated with lower 180-day
mortality. It is difficult to ascertain whether this is a true effect of
the anesthesia modality or a reflection of underlying bias not
eliminated by propensity matching. Studies have suggested 30-day
mortality may underestimate outcomes, and longer-term outcomes may be
better metrics for assessing hospital performance and patient
outcomes.34
Several studies have compared costs between MAC and GA in
TAVR.14, 24, 25, 35-37 This study demonstrated
significant differences between anesthesia modalities in OR time, ICU
LOS, and total LOS after propensity-matching. It was hypothesized that
these differences would translate to reductions in patient charges, but
this was not the case. The absence of significant cost savings among MAC
TAVR has been reported in a prior unmatched single-center study, which
similarly found decreased ICU and hospital LOS with MAC but no cost
benefit.36 The authors found similarity in costs was
mostly driven by increased “miscellaneous” costs in the MAC group,
which primarily included the costs of treating unrelated comorbidities
during the hospital stay. A 2014 retrospective unmatched comparison
between TAVR via “minimalist approach,” involving MAC and the use of
catheterization lab, and a “standard approach,” which involved GA and
the use of a hybrid OR, found the minimalist approach was associated
with an average cost reduction of $9,892.24 The high
cost of a hybrid OR likely explains these findings, and the use of MAC
may not have driven savings.38, 39 A 2017
propensity-matched analysis found a 28% decrease in direct cost when
MAC was used for TAVR.25 However, this latter study
was of high-risk patients, with a large percentage of cases being done
by transapical approach. Average hospital stay for both arms was nearly
double that observed in this series, highlighting the limited
generalizability of the study to more recent trends in the use of TAVR.
Other comparisons of high-risk patients, confounded by baseline
differences between groups, have demonstrated reduced OR, ICU, and total
hospital LOS times with the use of MAC for TAVR.35, 37With the inclusion of intermediate and low risk patients, the data
presented herein offers more generalizability to the population
currently treated with TAVR.
Hospital and operator volume have been demonstrated to correlate with
outcomes in TAVR.40-42 To minimize the impact of
physician and institutional experience on OR time, we compared MAC and
GA TAVR within the year 2016. This year was chosen as it had the most
even distribution of TAVR between MAC and GA and followed over 60 cases
and two years of institutional experience with TAVR. In this analysis,
MAC was still associated with significantly shorter OR time, suggesting
the difference is due to the anesthesia modality itself, not confounders
such as increased institutional experience or new deployment devices.
Physician experience and case volume vary considerably between studies,
which poses a challenge when comparing our findings to previous
analyses. Among the TAVR programs developed at 13 national VAMC’s, our
center is the highest volume VAMC TAVR program based on internal data.
While prior studies were performed at non-VA hospitals, this is the
first study comparing costs between MAC and GA TAVR at a VAMC, which has
a very standardized cost structure. Differences in administrative,
clinical, and billing operations between non-VA and VA centers may limit
extrapolation of costs to non-VA centers. For instance, the relative
value units (RVU) used for reimbursement purposes are calculated
differently between VAMCs and other hospitals. RVUs defined by the
Centers for Medicare and Medicaid Services (CMS) for non-VA facilities
are based on factors like technical skill, stress, and judgement
required for a treatment associated with a current procedural
terminology (CPT) code. The VA instead uses a unique RVU formula that is
based on the resources used for a service (e.g., OR time, ICU LOS) and
further specifies RVUs for several different resource categories (labor,
supplies, overhead, contractors, etc.).43 It can be
difficult to extrapolate costs between VA and non-VA hospitals, as
studies of these differences are limited. Healthcare costs for end-stage
renal disease patients have been shown to be more expensive at VA
hospitals compared to at non-VA hospitals, but studies like this are
confounded by comorbidity distribution and different approaches to
medical management.44 More recent comparisons have
demonstrated increased costs at VA hospitals compared to community
hospitals for coronary artery bypass grafting, but lower costs for
percutaneous coronary intervention.45 Cost data for
other hospitals would include indirect costs, such as administrative
expenses.
While our study was performed at the highest volume VA TAVR program, it
remains limited by the propensity matched sample size and its
retrospective nature. Additionally, the VA patient population is almost
exclusively male, limiting the generalizability of our results. Despite
these limitations, our study demonstrates strong advantages to the use
of MAC for TAVR. In a high volume VAMC, TAVR performed under MAC is
safe, leads to an improvement in OR efficiency, and reduces ICU and
hospital length of stay, but does not translate into cost savings.