Discussion
The present study describes the HT treatment decision algorithm for a
defined cohort of consecutives patients with severe AS from a tertiary
referral hospital and two additional satellite hospitals. A local
consensus document was used to define the patients who needed to be
discussed in the HT. After HT discussion, more than 50% of the patients
were allocated to the TAVR group, and approximately 20% to each of the
other treatment groups. Baseline characteristics that determined the
allocation group were mainly older age, concomitant MR, surgical risk
scores, renal function and frailty. Patients without intervention had a
1-year mortality rate which was three times higher than either of the
intervention groups, mainly driven by cardiovascular death. Readmission
rates at 1-year was close to 50% in both the TAVR and SAVR groups.
The HT concept stems from 2 randomized controlled trials comparing
surgical and percutaneous strategies in coronary artery disease and AS
(10,11). The purpose of the HT in these trials was to choose suitable
candidates for both interventions. The function of contemporary HT
discussions should be to apply the clinical acumen of the HT members to
the selection of patients for medical, transcatheter and surgical
treatment, as basing this decision purely on risk scoring systems may
not properly reflect specific high-risk characteristics in some patients
(12). As such, the HT approach provides a patient-specific decision
based on the overall patient profile.
The role of the HT has become more prominent in recent years since the
introduction of TAVR as an alternative treatment for severe AS,
particularly in elderly patients with multiple comorbidities. The
treatment of severe AS is a perpetually evolving area, with current
evidence attesting to its value in lower risk patients (13,14), making
continuous evaluation of HT decisions in this changing clinical
environment of paramount importance. In our center, the HT format was
designed by cardiac surgeons, and interventional, clinical and imaging
cardiologists who take part in weekly meetings. Referral physicians also
participated via video-link. The routine schedule of a weekly meeting
dedicated entirely to patients with AS, allowed all resources to be
focused on these patients to optimize the HT decision making process.
The number of candidates referred to the HT increased over the years,
suggesting a greater penetrance of the HT concept and, probably, greater
value being placed in HT decisions by the referring physicians.
A critical aspect of the HT is to determine which patients would not
benefit from an invasive approach and avoid futility (15). Reasons to
avoid an invasive treatment were heterogeneous, but in general invasive
treatment was avoided in patients considered to have a high-risk of
mortality. The most common reasons to avoid invasive treatment were
severe comorbidities or acute and critical illness. Despite careful
decision making to avoid futile invasive procedures, a relatively high
percentage of patients who underwent an invasive treatment died
(~15%) or were readmitted (~40%)
within one year, suggesting that the patient selection process could
still be improved. Specially, patients referred to the TAVR group were
very old and had several significant comorbidities, which conferred a
high risk of dying from non-cardiovascular causes (more than half of the
patients in this cohort). Continuous evaluation of the HT decisions,
with a special focus on these high-risk patients, should be implemented
to identify patients at higher risk of mortality and attempt to diminish
future futile interventions. In our cohort HT decisions could be
reconsidered if changes in the clinical situation arose and
approximately 10% of the patients were subsequently changed from the
initial allocated group.
Several factors (older age, significant MR, frailty, eGFR and surgical
risk scores) defined by the CART analysis impacted the clinical decision
making in accordance to others (6). Significant MR was identified as an
important co-morbidity which increased the likelihood of referring the
patient for surgery, particularly in those without frailty. However, the
concomitant role of significant MR in patients with AS is still
unresolved (16). Previous reports showed a negative impact of untreated
baseline ≥ grade III MR in both TAVR (17,18) and SAVR populations
(19,20). On the other hand, a double valve intervention is associated to
higher perioperative mortality than isolated SAVR (21). Among those with
significant MR, frailty was a determinant factor to choose TAVR over
SAVR. Frailty has been described as a strong predictor of
peri-procedural complications and mid-term outcomes after cardiac
surgery (22,23). However, in the setting of TAVR, frailty may not be
significantly related to peri-procedural mortality or morbidity;
although, it appears to have impact on mid-term outcomes (24). This may
be due to the less physiologically stressful nature of TAVR compared to
SAVR (25).
In our study, chronic kidney disease (CKD), a frequent comorbidity in
patients with AS(26), increased the chance of referring the patient for
TAVR over SAVR. A previous study in patients with CKD has shown better
short-term outcomes in TAVR compared to SAVR (27). Despite the
well-recognized limitation of surgical risk scores in predicting
outcomes in TAVR patients, systematic calculation of theses scores
provided useful and objective information for the HT discussion. Current
European and American guidelines support their use for surgical risk
stratification based on the inclusion criteria of randomized trials
(2,3,28). Moreover, surgical scores still provide a general risk
prediction in individualized patient and may predict a futile
intervention (29).
The purpose of the study was not to compare different therapeutic
options, due to the non-randomized nature of the interventions and the
selection bias by the HT. However, general results were in accordance
with previous registries and randomized trials with high-risk
patients(11,28). While acute kidney injury, new onset atrial
fibrillation and significant bleeding were higher in the SAVR group,
vascular complications were more frequent in TAVR patients. Stroke and
in-hospital mortality were similar. While residual aortic regurgitation
tended to be higher in TAVR patients, valve hemodynamics overall were
better in this group. Also, both invasive groups showed similar results
in terms of long-term mortality and rehospitalization rates.
This study has the inherent limitations of any observational study
without an external adjudication event committee. However, it
demonstrates the practical real-world issues related to the current
management of AS patients within a HT format. In this study we present
the results of a single HT with a limited sample size. Additionally, not
all patients with AS were evaluated by the HT. Although, wide-ranging
criteria were prospectively set to define those that should be referred
to the HT, a number of patients were treated without HT discussion and
were not included in our study. Patients in the MT arm were not
specifically followed-up and outcomes were identified in a retrospective
fashion. This study spans the time period before the publication of
trials on low risk patients, and the results cannot be extrapolated to
current practice relating to patients in lower risk groups.