Long-term stability of P wave sensing in single lead XXXX pacing: clinical versus subclinical atrial undersensing.

@entity1 @entity713 @entity955 @entity3867
Optimal function of a single lead P wave synchronous rate adaptive ventricular pacing system ( @entity3867 ) requires reliable P wave sensing over time and during daily activities. The stability of P wave sensing and the incidence of sensitivity reprogramming in a single pass lead with a diagonally arranged bipole was assessed in 30 @entity1 with complete @entity713 over a follow-up period of 12 +/- 1 months (range 6 months to 3 years). Atrial sensing was assessed during clinic visits, by physical maneuvers (postural changes, breathing, Valsalva maneuver, walking and isometric exercise), maximum treadmill exercise and Holter recordings. P wave amplitude at implantation was 1.21 +/- 0.09 (0.5-3.6) mV, and the atrial sensing threshold remained stable over the entire period of follow-up. Using an atrial sensitivity based on twice the sensing threshold at 1 month, P wave undersensing was found in 2, 4, 3, and 7 @entity1 during clinic visit, physical maneuvers, exercise, and Holter recordings, respectively. Atrial sensitivity reprogramming was performed in three @entity1 based on the correction of undersensing during physical maneuvers. Although eight @entity1 had atrial undersensing on Holter recordings, the number of undersensed P waves was small (total 101 beats or 0.013% +/- 0.001% of total ventricular beats) and no @entity1 was symptomatic. One @entity1 had intermittent atrial undersensing at the highest sensitivity, but the @entity3867 mode was still functional most of the time. No @entity1 had myopotential interference at the programmed sensitivity. One @entity1 developed chronic @entity955 and was programmed to the VVIR mode. Thus, single lead @entity3867 pacing is a stable pacing mode in 97% of @entity1 .(ABSTRACT TRUNCATED AT 250 WORDS)
