1Uniklinik RWTH Aachen Med. Klinik I - Kardiologie, Angiologie und Internistische Intensivmedizin Aachen, Deutschland; 2Maastricht UMC+Heart+Vascular Center Dept. of Physiology Maastricht, Niederlande
Background and Aims: Cryoballoon ablation of atrial fibrillation alters a significant amount of vital myocardium that contributes to its electrical activity. However, the effect of pulmonary vein isolation on the P-wave is unclear. The aim of this investigation was to determine the contribution of each pulmonary vein (PV) using means of signal-averaged P-wave analysis.
Methods: Unfiltered high-resolution (2000 samples/second) ECGs were obtained for 5 minutes before and after isolation of each PV with 12 standard and 10 additional lead positions (x01-x10). The additional lead positions were determined in preceding investigations for maximal atrial electrical energy deflection on the body surface and for positions not monitored by standard leads. Signal-averaged ECGs (SAECG) were calculated and analyzed using customized software in Matlab. A two-tailed paired t-test was used to test for significance. 66 patients were included in the analysis.
Results: Significant changes for several ECG parameters and lead combinations were found (Table 1). Averaged across all derivatives, P-wave terminal force (PWTF, 3.08±1.99 mV*ms vs. 2.63±1.76 mV*ms, p = 0.022), P-wave complexity (PWC, 2.05±0.65 vs. 1.79±0.51, p < 0.001), and sample entropy (SaE, 0.210±0.039 au vs. 0.187±0.028 au, p < 0.001) were reduced after completion of pulmonary vein isolation. After ablating the left pulmonary veins (LPV), PWTF (3.07±2.05 mV*ms vs. 2.84±1.88 mV*ms, p = 0.044), PWC (2.02±0.64 vs. 1.90±0.57, p = 0.047), and SaE (0.210±0.039 au vs. 0.197±0.031 au, p < 0.001) decreased. Only SaE was reduced after ablation of the right pulmonary veins (RPV, 0.196±0.031 au vs. 0.190 ±0.027 au, p = 0.049).
Conclusion: Pulmonary vein isolation in atrial fibrillation has a significant effect on signal-averaged P-wave. These effects are most pronounced after ablation of the LPV. PWTF, PWC and SaE are the most promising parameters to determine the effect of catheter ablation and might be used as a potential indicator for a successful ablation.
Table 1 Ablation effect per pulmonary vein for different P-wave parameters
|
P-wave parameter P-wave parameter |
Pulmonary vein PV |
Baseline Mean±SD |
Postablation Mean±SD |
P P |
|
Terminal Force [mV*ms] |
Post procedure [N=64] LPV [N=63] RPV [N=63] |
3.08±1.99 3.07±2.05 2.82±1.82 |
2.63±1.76 2.84±1.88 2.62±1.73 |
0.022 0.044 0.105 |
|
Complexity [N] |
Post procedure [N=64] LPV [N=64] RPV [N=64] |
2.05±0.65 2.02±0.64 1.90±0.58 |
1.79±0.51 1.90±0.57 1.84±0.55 |
<0.001 0.047 0.376 |
|
Sample Entropy [au] |
Post procedure [N=64] LPV [N=64] RPV [N=64] |
0.210±0.039 0.210±0.039 0.196±0.031 |
0.187±0.028 0.197±0.031 0.190±0.027 |
<0.001 <0.001 0.049 |
Values are given as mean ± SD averaged across all derivatives. Comparison before (baseline) and after
ablation (postablation) with two-tailed paired t-test. Post procedure: Measurement before and after the
entire procedure. LPV: Left pulmonary veins. RPV: Right pulmonary veins.
Figure 1 Change in P-wave morphology after single pulmonary vein isolation
Example of a subject's signal-averaged P-wave before (baseline) and after ablation of the left superior pulmonary vein (LSPV), left inferior
pulmonary vein (LIPV), right superior pulmonary vein (RSPV), and right inferior pulmonary vein (RIPV) in lead II. The order of ablation is
indicated by the arrows. As the procedure progresses, the P-wave becomes less complex and irregular.