Postoperative ergometry-guided programming does not prevent T-wave oversensing and inappropriate shocks in S-ICD patients

Background: T-wave oversensing (TWOS) is a feared complication after subcutaneous implantable cardioverter-defibrillator (S-ICD) implantation, potentially leading to inappropriate shocks (IS) with tremendous impact on quality of life.

Hypothesis: Postoperative ergometry facilitates primary and secondary prevention of TWOS or other potential causes of IS and optimizes S-ICD programming.

Methods: We analyze the impact of ergometry guided-programming (EMGP) on primary and secondary prevention of TWOS/IS in S-ICD patients, we screened 146 patients implanted in our center (2010-2016) for the incidence of TWOS/IS during postoperative ergometry. Furthermore, to evaluate the outcome in 123 eligible patients complete follow-up (FU) of at least 6 months up to 2 years was retrospectively analyzed.

Results: (1) Primary prevention: TWOS could only be provoked postoperatively in 3.7% of patients (n = 3/82). FU analyses did not reveal significant differences compared to our control group (Ctrl: n = 6/61, 9.8% vs EMGP: n = 5/62, 8.1%; P = 0.731). Further subgroup analyses of patients with postoperative ergometry in the close postoperative period (< 7 days; n = 3/45, 6.7%; P = 0.563) did not yield any significant difference. (2) Secondary prevention: We found various causes of TWOS/IS. In patients who underwent reprogramming due to previous TWOS/IS events we observed a 66.7% (n = 6/9) reduction of TWOS/IS using EMGP.

Conclusion: TWOS/IS has various causes while not all cases are exercise-associated. Postoperative ergometry does not seem to be useful for primary prevention. Further trials need to investigate the potential benefit of EMGP for secondary prevention of TWOS/IS.