Incidence and Characteristics of Far-Field R Wave Sensing in the Low Right Atrial Septum

Abstract

Background: Although it remains controversial, low atrial septal (LAS) pacing may prevent atrial tachyarrhythmias in selected patients. While far-field R wave (FFRW) sensing in this region seems more likely than in right atrial appendage, it has not been studied formally. Methods: 31 patients (74±10 years, 12 males) who underwent dual-chamber pacemaker implantations were investigated in randomly use of different tip-ring electrode distances of bipolar atrial leads at LAS region; 10 mm of tip-ring inter-electrode distance in 15 and 1.1 mm in 16 patients. FFRW sensing was measured in the setting with shortest post ventricular atrial blanking period of 60 ms and with 0.1 mV of atrial sensitivity, increment step-by-step in every 0.1 mV. Results: The incidence of FFRW sensing in atrial sensitivity of more than 0.1 mV and 0.5 mV were observed in 24 (77%) and in 9 patients (29%), respectively. The use of 10 mm tip-ring electrode distance of bipolar atrial lead (HR 10.32, 95% CI 1.04–102.74, P=0.047) and the presence of left ventricular hypertrophy (LVH) on electrocardiogram (HR 14.51, 95% CI 1.17–179.98, P=0.037) showed both independent predictors for FFRW sensing. Conclusions: The incidence of FFRW sensing is commonly observed and shorter tip-ring electrode distance of bipolar atrial lead is recommended, particularly in presence of LVH on electrocardiogram in the LAS region.