Accelerated pacing reduces left heart filling pressures: a novel therapy for heart failure with preserved ejection fraction?

Abstract Background The recent MyPACE trial demonstrated significant improvement of quality-of-life, physical activity, and atrial fibrillation (AF) burden with accelerated pacing as compared to the standard 60bpm back-up rate setting in patients with heart failure with preserved ejection fraction (HFpEF) and indication for pacemaker therapy. We hypothesized that a potential working mechanism underlying these improved outcomes lies in the reduction of left heart filling pressures during accelerated pacing, reducing congestion and atrial stretch. Aim To assess the acute effects of accelerated atrial pacing on left heart filling pressures in consecutive AF patients undergoing catheter ablation. Methods Fifty AF patients undergoing catheter ablation were prospectively enrolled for accelerated atrial pacing. As illustrated in Figure 1, pacing was performed proximally in coronary sinus (CS). Pacing rate was increased incrementally from resting heart rate by 10-bpm increments up to Wenckebach rhythm, with 30-sec intervals of pacing on and off for hemodynamic stabilization. Left atrial pressure (LAP) was continuously monitored via a fluid-filled transseptal sheath (SL0 sheath, Abbott). Acute pacing-induced changes in mean LAP and PR-interval were evaluated at each pacing rate and compared between resting heart rate, the patient-specific optimal heart rate (i.e., the rate resulting in the lowest mean LAP), and the maximum pacing rate. Results Atrial pacing acutely decreased mean LAP from 14.8[9.8; 18.4] to 12.8[8.5; 15.8]mmHg (median[IQR], p<0.001) as heart rate increased from 51[47; 61] to 90[70; 100]bpm (p<0.001) (Figure 2, resting versus optimal category). Among the 50 patients included, only 4 did not exhibit a decrease in LAP. Further increasing pacing rate to a maximum of 130[100; 140]bpm resulted in an acute LAP increase to 16.2[12.7; 19.9]mmHg (p<0.001) to values above resting mean LAP. Accelerated pacing induced negative AV dromotropy, i.e., lengthening of the PR-interval from 169[150; 185] to 186[164; 209]ms (p=0.003) and 270[217; 310]ms (p<0.001). Conclusion Our study demonstrated that moderately accelerated atrial pacing reduced mean LAP in AF patients undergoing catheter ablation. While our primary focus was on acute response in AF patients, the reduction in mean LAP during moderate pacing rates may suggest a promising therapeutic approach for managing HFpEF patients. However, caution is warranted as pacing rates beyond the optimal range led to a marked increase in LAP. Additionally, increasing pacing rates were observed to induce varying degrees of AV-node dromotropy, which potentially modulates therapy response.Fig 1. Overview of clinical protocolFig 2. Response to accelerated pacing