3.5 Predictors of mortality after TAVI
We used Cox proportional hazard models to analyze the predictors of
mortality after TAVI, as shown in Table 4. The univariate analysis
revealed that preoperative serum albumin and hemoglobin were associated
with mortality. In the multivariate analysis, only preoperative serum
albumin showed a tendency towards predicting mortality, however the
association did not reach statistical significance (hazard ratio: 0.54,
95% confidence interval CI: 0.65–1.03, p=0.08).
DISCUSSION
Life expectancy varies from country to country and in addition, the
healthcare systems of each country are unique in themselves. In Japan,
where health insurance is a requirement, the healthcare delivery
environment is different as compared to other countries where health
insurance is not a requirement. There are several reports on the
outcomes of TAVI for nonagenarians in Western countries.6-8 However, to our knowledge, this is the first
report to investigate outcomes in the Japanese population. Takeji et al.
reported that the current hospital mortality rate of TAVI in Japan is
1.3%, suggesting that it has a high success rate and is being performed
safely with very low mortality. 3 This study revealed
that TAVI in nonagenarians have excellent early- and mid-term outcomes.
The in-hospital mortality rate of our nonagenarian cohort was 0%, which
was statistically equivalent to the younger patients’ cohort (0%).
Although hospital stays were longer in the nonagenarian cohort, the
other early outcomes were comparable, indicating that TAVI can be safely
performed even in very elderly populations. Investigators from Western
countries have shown that TAVI in nonagenarians can achieve acceptable
in-hospital outcomes and that age alone should not exclude patients from
treatment, 6-8 a viewpoint that is supported by our
findings.
A decade ago, SAVR was the only effective therapy for aortic valve
stenosis. The development of TAVI has dramatically changed the surgical
treatment of aortic valve stenosis. Previous studies with nonagenarian
cohorts showed that early mortality after SAVR ranged from 11% to 17%.9,10 In contrast, the in-hospital or 30-day mortality
rates after TAVI in nonagenarians has been reported as 0%–8.7% in
recent observational studies, showing a distinct advantage.6,7 In fact, there were no in-hospital or 30-day
mortalities in our nonagenarian cohort. Although the long-term results
of TAVI remain unclear, it is a useful therapeutic option and a
reasonable alternative to SAVR in nonagenarians based on their
relatively short life expectancy.
Our results showed that nonagenarian patients required longer hospital
stays. Prolonged hospitalization can cause postoperative muscle weakness
and deterioration of activities of daily living (ADL). Stehli et al.
reported that deterioration of ADL after TAVI is more frequent in older
patients and that 25% of nonagenarians transition to aged-care
facilities within 1 year after TAVI. 7 We believe that
this points to a particular disadvantage of TAVI in very elderly
patients. In this cohort, only 15 of 23 nonagenarians had frailty
assessment data available as these assessments were not routinely
performed during the early period of our series. Although the sample
size is limited, we could not find any deterioration in frailty status
in the early phase after TAVI (Supplemental table1). However, the data
is insufficient for assessing the possible future changes in ADL and
quality of life. Unconscious scaling back of physical activity in
patients with cardiac disease is a well-characterized phenomenon.
Gradual improvement in activity may be possible after recovery of
cardiac function (Supplemental Figure1). Further investigations into
long-term ADL outcomes are required.
The freedom from cardiac events rates in each group were almost
equivalent in this study. Interestingly no late cardiac deaths occurred
in the nonagenarian cohort. The Japanese Ministry of Health, Labor and
Welfare reported that the top 5 causes of mortality in nonagenarians are
cardiac disease, pneumonia, senility, cerebrovascular disease, and
malignancy. 11 In our nonagenarian cohort, the causes
of late mortality were pneumonia in 3 patients, other infectious disease
in 3, and malignancy in 1, but there were no cardiac deaths. Thus, TAVI
may contribute to the avoidance of cardiac death in nonagenarians.
The wide-spread adoption of TAVI and the aging of the population have
led to an increase in the number of procedures performed worldwide. The
identification of prognostic factors is thus essential for patient
selection and stratification in the TAVI era. Various predictors of
prognosis after TAVI have been reported; for example, anemia, intra- or
post-operative blood transfusion, psoas muscle area, and appetite
immediately before discharge were associated with postprocedural
mortality. 12-15 In this study, lower preoperative
serum albumin seemed to be associated with poor long-term outcomes, but
the results were not statistically significant (p=0.08). Serum albumin
is a known frailty marker and may be a potential predictor of TAVI
outcomes. In this study, age was not a predictor of prognosis despite
generally being a significant factor in all procedures. Older patients
have more co-morbidities and are at a higher operative risk. In fact,
major operative risk scores, including the STS risk score, EuroSCORE,
and JapanSCORE, identified older age as independent operative risk
factor. 16-18 We believe that our results could be
explained by the equivalent risk scores in the nonagenarian and the
younger age groups (Table 1). This indicates that the nonagenarian
patients may have been selected to some degree and be in relatively
better condition as compared to the younger group, which would affect
the assessment of age as a prognostic indicator.
This study has several limitations. Since this was a retrospective,
observational study, selection bias may be present. The sample size was
limited because our hospital is not a high-volume center. Furthermore,
data regarding outcomes of conservative medical therapy in nonagenarian
aortic stenosis patients were not available.
CONCLUSIONS
The early and mid-term clinical outcomes of TAVI in selected
nonagenarians were comparable to those in younger patients and TAVI may
contribute to the prevention of cardiac death in nonagenarians. These
findings indicate that TAVI may be an effective treatment for aortic
stenosis, even in nonagenarian patients.