Discussion
To the best of our knowledge, this is the first study demonstrating the
prevalence, temporal trends and impact of TTS in patients with AIS. In
this nationally representative sample of hospitalizations with AIS, we
demonstrate an estimated 0.4% of TTS cases from 2007-14 which were
associated with higher all-cause mortality, adverse hospital-related
complications and longer LOS as compared to AIS patients without TTS.
This rate is nearly 20 times higher than the TTS rate reported in the
general inpatient population (0.02%). Previous analyses studying TTS in
AIS have either been single-center studies or case reports [12-15].
There has been an increasing trend in the prevalence of TTS with AIS
from 2007-2014, with the highest number of cases recorded during 2014
(N=1081). The highest proportion of TTS cases among AIS were recorded
among elderly >65 years (69.8%) and female (82.2%)
patients. A study by Jung et al. of 23 AIS patients reported similar
findings of increasing rates of TTS among the elderly with a mean age of
70.7±13.9 years consisting predominantly of females (73.9%) [16].
Female predominance was seen in another study by Templin et al [17].
Consistent with our study findings, a study by
Murugiah
et al. reported white patients representing almost 90.2% of the total
TTS population [18].
The baseline characteristics and comorbidities could define prognosis in
AIS patients with TTS. We observed a significantly higher prevalence of
congestive heart failure, chronic pulmonary disease, coagulopathy, fluid
and electrolytes disorders, hypothyroidism, obesity, previous myocardial
infarction, depression and coronary atherosclerosis among AIS patients
with TTS. In one study by
Brinjikji
et al. reported the higher prevalence of chronic cardiovascular
morbidities among TTS patients [19]. These data could help better
risk stratify patients at risk of TTS with AIS.
In our study, we observed higher odds of developing adverse events
during AIS hospitalizations with TTS. These included cardiogenic shock
(OR=8.84), cardiac arrest (OR=3.17), and venous thromboembolism
(OR=1.68). Moreover, the AIS-TTS cohort was at higher risk of developing
respiratory failure (OR=3.13) and requiring mechanical
ventilation/intubation (OR=4.09) more frequently. Increased risk of
cardiovascular complications in AIS-TTS cohort could be due to higher
proportion of elderly patients with underlying chronic medical illness.
Similar findings were observed in a study by
Brinjikji
et al, in which higher odds of complications were seen among elderly
patients with underlying chronic cardiovascular risk factors [19].
TTS occurrence in AIS also had a worse impact on healthcare resource
utilization. We observed frequent step down of AIS-TTS cohort to more
chronic care centers including SNF, ICF etc. In addition, we observed an
extended hospital stay of TTS cohort (8.59±10.03 vs 5.22±6.24) compared
to non-TTS cohort. This could be attributed to increased risk of
complications requiring longer stay and more advanced care. Prolonged
hospital stay among AIS-TTS cohort was also associated with more than
two times higher mean total hospital charges ($85,854 vs $37,924).
This further signifies the importance of identifying AIS patients early
to prevent complications and associated economic repercussions.
The all-cause inpatient mortality observed in AIS patients with TTS was
double (10.2% vs 5.1%) than non-TTS cohort. In addition to the added
burden of TTS-related complications, this could be explained by the
higher prevalence of chronic comorbidities, which increases risk of
in-hospital adverse events among AIS patients with TTS. In a prospective
observational study, higher mortality risk along with adverse events was
observed in older age groups [20].