Background
Patients with adult congenital heart disease (ACHD) have an increased risk of arrhythmic and 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 electrocardiogram (ECG), which is often abnormal in ACHD patients. This study investigates the proportion of ACHD patients who meet the screening criteria for S‐ICD implantation.
Methods
A standard screening ECG was performed in 102 patients with complex ACHD (Tetralogy of Fallot, Fontan circulation, and transposition of the great arteries). This process was repeated postexercise 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 one suitable vector. The most common number of acceptable vectors in the eligible group was two (35% of total population). In only 12% of total population, all three vectors were suitable while only one vector was suitable in 28% of total population. The primary vector (equivalent of ECG lead III) was the most common suitable vector, found in 62% of participants who had appropriate sensing vectors. Twenty‐five (24.5%) patients failed to meet the S‐ICD screening criteria. Of these, 14 had repaired tetralogy of Fallot. A total of 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 one additional patient failed to meet the eligibility criteria.
Conclusions
A quarter of ACHD patients do not meet the eligibility criteria for the S‐ICD. However, more than 90% of patients with a Fontan circulation are suitable for an S‐ICD.
PurposeThe subcutaneous implantable cardiac defibrillator ICD (S-ICD) has been developed to reduce the risk of lead complications in patients requiring prophylactic ICDs. It has also been recommended for patients with adult congenital heart disease (ACHD) who are at risk of sudden cardiac death (SCD) and often have complex cardiac anatomy, preventing the implantation of a transvenous system. It is unclear how many patients with ACHD may be suitable for a S-ICD.MethodsThe S-ICD screening protocol was carried out in three ACHD populations; Tetralogy of Fallot (TOF), complete transposition of the great arteries (d-TGA) and Fontan. S-ICD eligibility and potential predictors of ineligibility were investigated.Results102 patients were recruited to this study, with 14 repeating the protocol post-exercise. Mean age was 27 (±15 years) and 53% male. 25 participants failed to meet the S-ICD screening criteria and were deemed ineligible, (23.5%), significantly greater than the proportion of ineligible patients in the general ICD population (p≤0.01). Exercise was not shown to have a significant impact on eligibility. A broad QRS duration, small R:TMAX and a large RVEDV were associated with ineligibility.Abstract 3 Figure 1Disease distribution between the eligible and ineligible groupsConclusionThis data suggests that a significant proportion of ACHD patients would not be candidates for the S-ICD, due to the risk of inappropriate sensing. This emphasises an importance of alternative treatment options for this population at a high risk of SCD. Substantial development of the current S-ICD sensing algorithm would be required to increase eligibility.
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