Dialytic interval and the timing of electrocardiographic screening for subcutaneous cardioverter-defibrillator placement in chronic hemodialysis patients

Background: Hemodialysis (HD) patients have a high risk of sudden death but limited vascular access and high complication rates from transvenous implantable cardioverter-defibrillators (ICDs). Subcutaneous ICDs (S-ICD) may be an alternative, but dynamic ECG changes may result in inappropriate shocks. This study aims to define the screen failure rate for S-ICD in patients pre- and post-HD. Methods: ECG waveforms were obtained using electrodes mimicking the S-ICD sensing vectors in an unselected test group of chronic HD patients and a control group of ICD-eligible non-dialysis patients. Participants passed screening if their QRS and T-waves fit within the screening template in supine and standing positions in any lead. Test group participants were screened before and after HD and control group patients were screened at two separate time points. HD patients were stratified into the four following groups: (A) passed screening before and after HD, (B) failed screening before but passed after HD, (C) passed screening before but failed after HD, and (D) failed screening before and after HD. Patients in group A passed the screening for ICD implantation, and patients in groups B, C, and D failed the screening for ICD implantation. Control patients were similarly classified by pass/fail status at the two assessment points. Results: Of the 76 patients enrolled, 51 were HD patients and 25 were controls. Of the 51 HD patients, 43 (84%) were in group A, four participants (8%) were in group B, one (2%) was in group C, and three participants (6%) were in group D. There were no differences in any of the clinical or demographic variables between the pass and fail test HD groups. None of the 25 controls failed the screening at either time point (p = 0.047 vs HD patients). Conclusions: Overall, HD patients were more likely to fail S-ICD screening compared to non-HD patients (16 v 0%, p = 0.047) and are more likely to do so prior to HD. Patients on HD should be screened at multiple time points around the dialytic interval to reduce the risk of inappropriate shocks.