Lead Performance and Echocardiographic Outcomes for Delayed Bundle Capture Loss During Conduction System Pacing

Conduction system pacing (CSP) is increasingly recognized for mitigating the adverse hemodynamic effects commonly associated with conventional ventricular pacing. However, there is limited data on the lead performance and echocardiographic outcomes for delayed bundle capture loss during CSP.

To evaluate the rate of complete loss of bundle capture/correction during CSP and assess the subsequent clinical outcomes.

Patients who underwent successful CSP lead implantation with indications for ventricular pacing or cardiac resynchronization therapy (CRT) were screened. The reasons for complete loss of capture or failed LBBB correction were identified, and subsequent clinical outcomes were analyzed.

Out of 2636 patients screened, nine experienced complete loss of bundle capture or LBBB correction during follow-up. Loss of capture was attributed to unexplained causes (n = 6), near-complete electrode dislodgement (n = 1), surgical damage (n = 1), and electrode malfunction (n = 1). The six patients with CRT indication and declining cardiac function underwent lead revision, with left ventricular ejection fraction (LVEF) improving from 40.6 ± 17.3% to 59.1 ± 6.0% at the last follow-up with the bundle capture threshold of 0.63 ± 0.14 V/0.5 ms. The remaining 3 atrioventricular block patients with stable cardiac function did not undergo lead revision and the local myocardium threshold of 0.58± 0.31 V/0.5 ms.

The incidence of complete capture loss during CSP is low recapturing/recorrecting the bundle significantly improves cardiac function in patients with CRT indications.