Eligibility for subcutaneous implantable cardioverter-defibrillators in the adult congenital heart disease population

Background
Patients with adult congenital heart disease (ACHD) have an increased risk of arrhythmic, sudden cardiac death. The subcutaneous implantable cardioverter defibrillator (S‐ICD) provides a potentially safer alternative to transvenous ICDs in ACHD. Suitability for S‐ICD depends on the surface ECG which is often abnormal in ACHD patients. This study investigates the proportion of ACHD patients who meet the screening criteria for S‐ICD

Methods
A standard screening ECG was performed in 102 patients with complex ACHD (Tetralogy of Fallot, Fontan Circulation, Transposition of the Great Arteries). This process was repeated post‐exercise for patients who also had an exercise test.

Results
Three quarters (75.4%) of ACHD patients meet screening criteria for an S‐ICD with at least 1 suitable vector. The most common number of acceptable vectors in the eligible group was 2 (35% of total population). In only 12% were all three vectors suitable whilst 28% had only 1. The primary vector (equivalent of ECG lead III) was the most common suitable vector, found in 62% of participants who had appropriate sensing vectors. 25 (24.5%) patients failed to meet the S‐ICD screening criteria. Of these, 14 had repaired tetralogy of Fallot. 92% of patients with a Fontan circulation met ECG screening criteria. Of those who had the protocol repeated following their cardiopulmonary exercise test (n = 14), only 1 additional patient failed eligibility criteria.

Conclusions
A quarter of ACHD patients do not meet eligibility criteria for the S‐ICD. However, more than 90% of patients with a Fontan circulation are suitable for an S‐ICD.