Subcutaneous implantable cardioverter defibrillator eligibility according to a novel automated screening tool and agreement with the standard manual electrocardiographic morphology tool.

Purpose: Since subcutaneous implantable cardioverter defibrillator (S-ICD) introduction, the pre-implant screening based on a dedicated manual ECG tool (MST) was required to assure adequate sensing by the S-ICD. A novel automated screening tool (AST) has been recently developed. We assessed and compared the pass rate with AST and MST, and we measured the agreement between screening tools.

Methods: Three electrodes were positioned at locations mimicking the placement of the S-ICD, and ECG recordings were collected in the supine and standing postures at rest. The three sensing vectors were analyzed with the MST and the AST. Eligibility was defined by the presence of at least one or two appropriate vectors in both postures.

Results: A total of 235 patients with an indication to ICD and no need for permanent pacing were enrolled. At least one suitable vector was identified in 214 (91%) patients with MST and 221 (94%) patients with AST (p = 0.219). At least two vectors were appropriate in 162 (69%) patients with MST and 187 (80%) patients with AST (p = 0.008). Overall, out of 1587 ECG analyzed, 1035 (65%) qualifying leads were identified with MST and 1111 (70%) with AST (p = 0.004). The agreement between the results of MST and AST ECG analysis was moderate (Kappa = 0.570; standard error = 0.022; CI = 0.526-0.613). The results were consistent regardless of the underlying cardiomyopathy. The most frequent reason for screening failure with MST was a high-amplitude T-wave (31% of failures). With AST, 23% of recordings that failed with MST for high-amplitude T-wave were classified as acceptable.

Conclusion: The AST is associated with higher pass rate than the standard MST. It seems more tolerant of high-amplitude T-waves. Consequently, the agreement between MST and AST findings was only moderate.