Abstract 8575: Effects of Permanent Left Atrial Pacing in Patients with Heart Failure and Preserved Ejection Fraction.

Abstract

Background Although numerous patients are suffering from heart failure with preserved ejection fraction (HFPEF), no specific treatments have been shown to be efficient as the underlying mechanisms involved in this entity are still poorly understood. We hypothesized that inter-atrial conduction delay (IACD) associated with a short left atrio-ventricular interval (LAVI) may impair left ventricular active filling as it reduces the left atrium “kick” which occurs against the closing mitral valve. We assessed the clinical efficacy and safety of left atrial pacing therapy as a new treatment to restore the left ventricular active filling in severe HFPEF patients with IACD and a short LAVI. Methods Six NYHA class III patients with severe HFPEF and no other cause for heart failure symptoms than a short LAVI with IACD were implanted with pacemakers for left atrial permanent stimulation via the coronary sinus (lead screwed inside the Cs at 1 to 2 cm from the ostium). All patients were in sinus rhythm with an IACD defined as a p wave prolongation greater than 120ms in lead II, normal QRS interval. During electrophysiological (EP) studies, they all had a left atrio-ventricular interval (LAVI) shorter than 70ms. None of them had a standard indication for pacemaker implantation. This double-blind, randomized, crossover study compared the responses of the patients during two periods: a two-week period of inactive pacing (ventricular inhibited pacing at a basic rate of 30 bpm) and a two-week period of active (left atrial permanent pacing with dedicated algorithm for AF prevention). The primary end point was the distance walked in six minutes (6MWD). The secondary endpoint was the patient's treatment preference. Results During the inactive phase, two patients developed an acute heart failure 24 and 72 hours after the pacemaker was turned off. The mean (±SD) distance walked in six minutes was 21 percent greater with active pacing (237 ± 30m vs. 187 ± 18m, P<0.001). Active pacing was preferred by 100 percent of the patients. Conclusions Although the beneficial effects of left atrial permanent pacing need to to be confirmed by larger studies, this new pacing strategy may improve exercise tolerance in patients with HFPEF and short left atrio-ventricular interval.