Discussion:
Our data demonstrates an increasing trend in pediatric ICD admissions
over time. These findings are in line with reported increasing rates of
pediatric ICD implantation over time . Cardiomyopathy was the most
common underlying diagnosis in all the years, likely due to the need for
hospitalization for other comorbidities and may reflect an increasing
trend in ICD utilization for primary prevention in patients with
cardiomyopathy. An underlying diagnosis of primary arrhythmia
demonstrated a decreasing trend in the rate of hospitalizations after
2006. Although data is not available to assess reasons for this decline,
we speculate that utilization of ICDs in primary arrhythmia patients may
be decreasing with evolving practices; as the knowledge of inappropriate
shocks, electrical storm, and alternative medical management strategies
improves among primary arrhythmia patients, ICD implantations may be
decreasing. For example, it is likely that more caution and
consideration is being taken before prophylactic ICD implantation among
patients with Long QT type 3 and Catecholaminergic Polymorphic
Ventricular Tachycardia. Patients with primary arrhythmias are also less
likely to have other comorbidities that may necessitate hospitalization.
Our data suggest that among hospitalizations for young patients with
ICDs, those with an underlying diagnosis of cardiomyopathy or congenital
heart disease have significantly higher odds of in-hospital death when
compared to those with primary arrhythmia diagnosis. While our study was
not powered to address the possible trend of increased mortality seen
among non-Hispanic Black race this may warrant further investigation in
the future.
We noted that a diagnosis of heart failure increased over time among ICD
admissions suggesting the possibility of increased utilization of ICDs
in heart failure patients. Prior studies have demonstrated increased
in-hospital mortality among patients admitted with heart failure who
have arrhythmias and Silka et al demonstrated abnormal ventricular
function to be significantly correlated with mortality among patients
with ICDs. Although exploratory, our multivariable analysis found that
only a diagnosis of heart failure was associated with in-hospital death,
increasing the odds of mortality among patients admitted with ICDs by
ten-fold (p < 0.001), independent of underlying diagnosis. Of
note, the mortality rate among ICD admissions with heart failure in our
cohort was 3.7%, which is lower than the previously reported mortality
rate of 7.3% in all heart-failure related hospitalizations. The KID
database is not designed to identify reasons for the lower mortality but
one might speculate that children with heart failure in whom an ICD is
implanted may be of a different risk profile than those who do not have
ICDs. For example, implantation of an ICD requires the ability for the
patient to tolerate not only the procedure, but anesthesia and
induction, and thus may be limited to patients with less procedural
risks. In addition, predicted survival of less than 1 year is a relative
contraindication for ICD implantation.
In this study, we were unable to determine the exact cause of death
based on diagnostic codes; however, our data suggests that in-hospital
deaths are less among patients with primary arrhythmia disorders and
higher among those with cardiomyopathy and congenital heart disease with
the driver of death mainly related to heart failure.