Clinical Results of Far‐Field R‐Wave Reduction with a Short Tip‐Ring Electrode

Background: Far‐field R‐wave (FFRW) sensing of the atrial lead of AAI or DDD pacemakers causes incorrect mode switches and remains a problem in patients with atrial arrhythmias in whom low voltage sensing is essential. We studied a pacing electrode with a short tip‐ring distance (1.1 mm). We compared our findings with recordings from a conventional electrode with a larger tip‐ring distance (10 mm). Methods: Thirty‐six consecutive patients with an indication for DDD pacing were implanted with the short tip‐ring electrode. Another 23 patients received the conventional electrode. FFRW and P‐wave amplitudes during pacing and intrinsic ventricular depolarization were measured at implantation. Measurements were repeated before hospital discharge and at follow‐up between 10 and 14 days after implantation. Results: P‐wave amplitude was slightly smaller in the short tip‐ring group (2.71 ± 1.04 vs 3.17 ± 1.30 mV in the conventional group, respectively, P = NS). All P‐waves exceeded 1.2 mV. FFRW during pacing was 0.07 ± 0.05 in the short tip‐ring group and 0.54 ± 0.32 mV in the conventional group (P < 0.001). FFRW during intrinsic rhythm was 0.08 ± 0.04 and 0.55 ± 0.31 mV, respectively (P < 0.001). The ratio between P‐wave and FFRW was 48.6 ± 27.2 in the short tip‐ring group and 7.3 ± 4.4 in the conventional group (P < 0.001). FFRW and P‐wave amplitudes did not change at hospital discharge or during follow‐up. Conclusion: FFRW can be suppressed without compromising P‐wave sensing by using a pacing electrode with a short tip‐ring distance. Whether reduced FFRW amplitude results in clinical endpoints remains to be determined.