Author Reply: S-ICD Eligibilities in Adults with Congenital Heart Disease

We thank Wang et al. for their interest in our article on S-ICD eligibility in adults with congenital heart disease (ACHD).1 Wang et al. emphasize that our results are in contrast to several previous ACHD studies,2-5 including one recent study from their group.2 Carefully reviewing the references, our results regarding S-ICD eligibility in ACHD patients (83%) are obviously in line with previous published data. In the studies mentioned by Wang et al., S-ICD eligibility was 75%,3 77%,4 and 75.4%.5 Further studies not mentioned by Wang et al. showed even higher eligibility rates of 93.5%6 and 86.7%.7 More precisely, the result of Wang et al.2 reporting only 60% S-ICD eligibility is exceptionally lower compared to the above-mentioned studies. Our eligibility rate lies even closer to the aforementioned mean of the published data than the eligibility rate from Wang et al.2 (Figure 1). The references added by Wang et al. therefore nicely extend the well-described underlying evidence in the field. Wang et al. highlight a discrepancy between the reported data in the figures and the results section in a previous version of our manuscript, which has already been corrected in the final version of the publication. In detail, 70 patients (70%) were found eligible in both left and right parasternal positions, 8 patients (8%) only in left, and 5 patients (5%) only in right parasternal position adding up to the 83 patients (83%) found eligible in either left and/or right parasternal position as correctly reported in the study (Figure 2). Thus, Figure 1 of our manuscript and the eligibility rate mentioned in the study are correct.1 Wang et al. mention that the discussion of our results was not sufficient and that details about the Boston Scientific programmer settings of the automated S-ICD screening test including SMART Pass function (ECG filtering settings)6 were not appropriately described in our study. Of note, the automated S-ICD screening test does not include or allow the SMART Pass function, since the SMART Pass function is a filter setting of implanted S-ICD devices, whereas the automated S-ICD screening test is a test performed with the device programmer. The automated screening test automatically evaluates vector eligibility using the Latitude Programmer Model 3120 (Boston Scientific Natick, MA, USA). Thus, no settings can be adjusted before or during the test. Colleagues familiar with this screening tool will confirm that the reason for failure is not provided by the programmer. Cases of the automated screening test unable to deliver a result have been previously reported and are often due to paced QRS complex, low R wave amplitudes, and electromagnetic interferences.8, 9 The ECG-based screening test was performed as standard of care, but was not the main focus of our study, since this has already been largely examined in ACHD patients in previous studies.2, 3, 5, 7, 10 Furthermore, Wang et al. propose a comparison of S-ICD eligibility in different positions (standing and supine) on the left and right parasternal position using McNemar's chi-square test. Clinicians performing S-ICD screening will agree, that the proposed analysis comparing S-ICD eligibility in different positions is irrelevant in clinical practice, since S-ICD eligibility is only met if at least one vector is eligible in both, supine and standing position. The statistical test requested by Wang et al. therefore seems superfluous.