Discussion
In the European Guidelines, ICD implantation is a class 1B
recommendation for patients with nonischemic heart failure, and a class
1A recommendation for patients with ischemic heart
failure.[7] However, no difference was found
between the long-term benefits of DCM patients and ICM patients
receiving ICD as primary prevention treatment in this study.
Patients with extensive comorbidity may experience less benefit from
ICDs than those with less comorbidity.[10] We can
see that patients in the ICM group have prevalence of hypertension and
diabetes than patients in the DCM group. In this study, 38% of deaths
were attributed to non-cardiovascular diseases, emphasizing the
importance of strict screening criteria for ICD implantation.
ICD
implantation in NICM patients had a less benefit, which provided a basis
for not implanting ICD in frail patients, which is in line with the
guidelines that recommend.[11, 12]
Cox regression analysis found that all-cause mortality of ICM was higher
than that of DCM group. Patients with more comorbidities benefited less
from ICD treatment. Therefore, it is not recommended to install ICDs in
patients who cannot tolerate or are not suitable for CRT treatment, VAD
(ventricular assist device), NYHA Class IV heart transplantation, or
patients with severe comorbidities. The life expectancy of these
patients is difficult to exceed One year, it is difficult to obtain
benefits from expensive ICD treatment. Studies have also shown that ICM
patients in NYHA II-III patients have a greater risk of death than NICM
patients, so it is more recommended to carry out drug or ICD primary
prevention treatment in the early stage of the
disease.[13]
As we know, ICD is superior to antiarrhythmic drugs in increasing
overall survival.[14] Studies have shown that, ICD
was superior to amiodarone for the prevention of
SCD.[15] In this study, due to the small number of
patients taking amiodarone, and rare arrhythmia events during the
follow-up results, so their effects could not be compared.
The European Guidelines have recommended ICD implantation in patients
with NYHA class II-III. Although ICD treatment could reduce the risk of
SCD in some NYHA class IV patients, these patients often survived less
than 1 year due to the presence of severe diabetes, cerebral infarction
and other non-cardiovascular diseases. Due to the high survival rate
(50% at 10 years), heart transplantation became a choice for patients
with severe HF.[16] However, due to the limited
donor heart, these patients had a very high risk of SCD while waiting
for surgery, which was a special indication for ICD implantation. Some
retrospective studies showed that the use of ICD in patients waiting for
heart transplantation can reduce overall mortality by 36% to
49%.[17] Interestingly, 2 patients in the DCM
group successfully received heart transplantation in this study.
Among the patients included in this study, 3 (12%) in the ICM group and
20 (37.7%) in the DCM group have received CRT
treatment.[18, 19] Reversing LV remodeling is one
of the most important effects of CRT. However, it is difficult for CRT
to reverse cardiac remodeling of ICM patients whose LV were covered with
scar tissues to the same extent as DCM, which was consistent with our
results.[20] In this study, more patients received
CRT-D treatment in the DCM group, which may be a choice based on the
patient’s situation in clinical practice, but there is a lack of
function evaluation after receiving CRT-D treatment in both groups.
Limitations of our research need to be recognized. The sample size of
this study was small, and the conclusions were greatly affected by
individual differences. Multi-center studies could be conducted in the
future.
In conclusion, DCM patients with ICD implantation compared could be
benefit with a reduction in the risk of all-cause mortality and
cardiovascular disease with ICM patients, while the occurrence of SCD
had no difference in two groups.