Discussion
At this relatively early point in our knowledge of CS, most
implementable changes found from studies this paper analysed will be
targeted at the “ground-level”. That is, aiding clinicians in their
practice to filter patients deemed best to benefit from ICD implantation
for CS. Review of the literature made it clear that balancing the higher
rates of appropriate therapy with the largely unknown, but likely
increased, likelihood of device complication in this younger patient
cohort is challenging but important. The crux of ICD usage in CS hinges
around scarring patterns and the consequential increased risk of
arrhythmia. Although made more challenging by the high heterogeneity of
the disease, identifying these high-risk patients and discussing
treatment options to achieve a shared but informed decision is
essential.
We have seen the influence that some of the discussed papers have had on
the management of ventricular arrhythmias in those with CS in several
iterations of guidance and recommendations, most recently in the ESC
Guidelines from 2022(23). More widely speaking this paper aims to
provide a stepping stone for further research to support revision of
these guidelines if necessary – especially relating to the information
we have amalgamated about the drawbacks of ICD implantation.
Although a consequence of the innate rarity of the condition, the low
cohort sizes seen in several of the previous studies lends itself to
statistically underpowered analyses and therefore limits the ability to
draw stronger conclusions. This highlights the need for larger-scale
trials that are prospective in nature to truly characterise the utility
of ICDs in CS. In particular, there is a need for more data surrounding
both device complication and inappropriate therapy. This should compare
a variety of different variables, examples of which may include
analysing ICD therapies in those treated with and without
immunosuppression, or perhaps looking at outcomes in patients with
sarcoid isolated to the heart versus those with systemic manifestations
of the disease.
Inappropriate therapy will likely remain an unavoidable complication of
ICD therapy. However, through improvement of VA therapy detection
systems and supraventricular tachycardia (SVT) discrimination
algorithms, rates of inappropriate therapy will be reduced, and will
make ICD implantation a more viable option for a greater proportion of
patients. We envisage machine learning to play a pivotal role in this by
using AI-based pattern recognition on an ever-growing collection of
patient datasets from devices and constantly refining the ‘correct
rhythm’ to deliver a shock to. We have already seen some advancements
made in this field recently(33), and expect this to grow further and
impact positively on those with CS as well.
Increasing clinician awareness alongside more accurate and improved
cardiovascular imaging & diagnostic testing has led to higher numbers
of cases being diagnosed each year. In the coming years, we would expect
this trend to continue to increase. We also picture formulation of a
more definitive diagnostic criteria that can be more specifically
applied to a variety of ethnic groups.