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.