P1910Impact of pulmonary vein antral isolation by radiofrequency catheter or cryoballoon on left atrial function assessed by volume-pressure loops
Authors: Karanasos A , Toutouzas K , Tyrovolas K , Efremidis M , Tsiachris D , Kordalis A , Karmpalioti M , Aggeli C , Prappa E , Karagiannis S , Stefanadis C , Gatzoulis K , Tousoulis D 
Published: October 2019

Abstract

Background
Atrial volume-pressure loops are used to assess left atrium (LA) function. Catheter ablation of paroxysmal atrial fibrillation (PAF) by pulmonary vein (PV) antral isolation can be performed either with radiofrequency (RF) catheter or with cryoballoon and might affect LA function.

Purpose
We explored a potential difference in changes in LA function by volume-pressure loops between patients with PAF undergoing either RF catheter or cryoballoon ablation.

Methods
Patients undergoing for the first time catheter ablation of PAF by PV antral isolation and PV-LA junction ablation, as clinically indicated, were enrolled from 2 centers. Each center enrolled consecutive patients undergoing PV antral isolation using the same method ie RF or cryoballoon ablation. Patients with severe mitral stenosis or regurgitation, any prosthetic valve, left atrial thrombus or severe systolic or diastolic dysfunction of the left ventricle were excluded. Pre and post procedure, all patients underwent real-time 3D transthoracic echocardiogram to evaluate volume changes of the LA during an entire cardiac cycle, while recording LA pressure by a 6F angiographic catheter following transseptal puncture. After the procedure, LA volume and pressure recordings were gated offline by ECG, and were used to plot the LA pressure as a function of LA volume, thus creating a volume-pressure loop. The A loop area is a measure of the LA booster pump function. The V loop area expresses the LA reservoir function. Pressure and volume data at the clockwise ascending limb of the volume-pressure loop were fitted to the exponential function P = bxea·V, where P = instantaneous LA pressure; V = LA volume; a is the passive elastic chamber stiffness constant (cm–3) that determines the slope of the exponential curve, and b is the elastic constant (mm Hg).

Results
34 patients with PAF were analysed, 12 treated with RF ablation and 22 with cryoablation. The procedure was uneventful in all cases. In the overall cohort, mean LA pressure, A-wave and V-wave amplitude were all increased post-procedurally (p<0.001); A-loop area decreased (p=0.001), whereas V-loop area increased (p=0.016). Although the elastic constant increased (p<0.001), there was no significant difference in the passive chamber elastic constant (p=0.30).
Changes in both A-loop and V-loop areas were similar between RF and cryoablation (p=0.18 and p=0.36, respectively). However, compared to cryoablation, RF ablation had a lower increase in the elastic constant (b=-2.24; 95% CI: −10.56 to −1.78), and a higher increase in the passive elastic chamber stiffness constant (b=0.078; 95% CI: 0.016 to 0.140).

Conclusion
Both in RF- and cryo-ablation and in a similar extent, the LA booster pump function is decreased, and LA reservoir function is increased. LA pressure is increased in RF ablation mainly due to an acute increase in LA stiffness, whereas in cryoablation this increase is observed in the absence of change in LA stiffness.