S-ICD Oversensing of Leadless Atrial Pacing Spikes

Subcutaneous implantable cardioverter-defibrillators (S-ICDs) and leadless pacemakers (LPs) are increasingly used together, although data on combined use are limited.

A 79-year-old man with ischemic cardiomyopathy and 2 prior episodes of bacteremia requiring transvenous implantable cardioverter-defibrillator lead extraction received an S-ICD. He later developed tachycardia-bradycardia syndrome. Given his prior lead infections, an atrial LP was placed. Testing during implantation revealed high pacing thresholds. Therefore, the LP was programmed to 6 V at 0.4 ms. Remote monitoring noted S-ICD oversensing of the atrial pacing spike. Reduction of his LP amplitude to 1.5 V at 0.4 ms resolved the oversensing.

The use of S-ICD and ventricular LP is well described and occasionally not feasible due to sensing interference. The use of an atrial LP with an S-ICD is uncommon, and sensing interference is unlikely. This case shows atrial LP interference with S-ICD sensing and highlights possible solutions.