Background. In patients with permanent
atrial fibrillation (AF) rate irregularity can cause symptoms and impair the
pumping function of the heart. Ventricular pacing at a rate close to the mean
spontaneous ventricular rate can result in a more stable ventricular rate. Specific
algorithms for automatic Ventricular Rate Stabilization (VRS) were designed and
implemented in commercially available pacemakers. To assess this dynamic rate
control we designed the RARE-PEARL
study: prospective, randomized, cross-over, double-blinded.
Methods. Patients with permanent AF, symptomatic episodes of brady-tachycardia,
left ventricular ejection fraction (LVEF) >40%, NYHA class I/II, were
eligible for enrolment. Each patient (n = 67) was implanted with a
single-chamber VVIR pacemaker (models C20 or T20, Vitatron BV, The Netherlands) equipped
with the VRS algorithm. At the end of a
four week of stabilization period, patients were randomized to VRS algorithm ON
or OFF (2 months) and then crossed-over for the second phase (2 months).
Primary endpoint was patient’s preference.
Results. Sixty six patients ended the study: 19 (29%) had no preference; 15
(23%) preferred the phase with the algorithm OFF, 32 (48%) algorithm ON (p<0.0001,
algorithm ON vs OFF). In 58% of patients the algorithm ON caused an increase of
ventricular pacing percentage > 10%. The ventricular pacing percentage was
82±10% with algorithm ON vs 59±26% with algorithm OFF (p<0.0001). Symptoms
did not differ significantly.
Conclusions. The VRS algorithm significantly increases the
ventricular pacing percentage in patients with permanent AF. This pacing
function is preferred by the majority of patients implanted with a
single-chamber VVIR pacemaker.
Credits: Eraldo Occhetta; Gianfranco Mazzocca; Carla Svetlich; Pietro Scipione; Alessandro Fabiani; Massimo Giammaria; Serafino Orazi; Giorgio Corbucci