Conventional and alternative preimplantation ECG screening for subcutaneous ICD in high risk hypertrophic cardiomyopathy patients

Abstract

IntroductionPatients with hypertrophic cardiomyopathy (HCM) relatively often fail preimplantation ECG screening for subcutaneous implantable cardioverter-defibrillator (S-ICD). We aimed to evaluate impact of conventional and alternative ECG electrodes placement on eligibility for S-ICD implantation in HCM patients at high risk of sudden cardiac death (SCD). We hypothesized that modified electrodes placement will influence QRS-T morphology and thus it will increase S-ICD eligibility in the screening process. Material and methodsThis study enrolled 17 HCM patients at high risk of SCD (5-year SCD risk above 5%) referred for an ICD implantation. ECG screening for S-ICD eligibility in horizontal and vertical position was performed in each patient, in two different screening electrodes configuration: conventional (recommended by manufacturer) and alternative (precordial electrodes shifted rightwards and lateral electrodes dorsally). We evaluated QRS and T waves amplitude as well as T wave index. Primary, secondary and alternate sensing vectors were assessed. ResultsPreimplantation ECG screening with alternative electrodes placement resulted in more sensing vectors that were screened successfully (77 vs. 88, p = 0.05). Modified screening combined with a standard one allowed more patients to qualify for S-ICD implantation (17/17 vs. 12/17, p = 0.04). Electrocardiographically, the alternative positioning of ECG electrodes resulted in significant decrease in absolute values of QRS complex and T waves amplitudes in almost all sensing vectors, which was responsible for successful screening. ConclusionsThe use of alternative placement of screening electrodes may be a valuable method to increase eligibility for S-ICD implantation in HCM patients at high risk of SCD.