Background: Left atrial low voltage areas (LVA) are associated with increased recurrence rates of atrial fibrillation (AF) after catheter ablation and can be a potential ablation target during the procedure. Therefore, noninvasive prediction of the presence and the distribution of LVA may help physicians to predict ablation outcomes and to guide antiarrhythmic management.
Material and methods: Seventy-three consecutive patients with atrial fibrillation undergoing first time left atrial ablation for paroxysmal or persistent AF were enrolled. P-wave properties (amplitude and duration) were measured in all limb and precordial leads in pre-interventional sinus rhythm surface ECGs and correlated with total LVA size. LVA were detected via high density low voltage maps of the left atrium in sinus rhythm. LVA were then manually encircled, their total size was calculated and given as a percentage of the total LA surface area.
Results: A significant, inverse correlation with LVA size was shown for P-wave amplitude for leads I, II, aVR, aVF, V1, V4, V5 and V6. Additionally, a significant positive correlation between LVA size and P-wave duration was shown for leads V1, V2 and V3. As the strongest correlation was shown for the amplitude in lead I (R = -0.578), this lead was used to find a potential cutoff for LVA prediction. The best cut-off for a P-wave amplitude in lead I to predict severe scarring (defined as LVA size >35%, according to UTAH stadium IV) was 0.062 mV with an area-under-the receiver-operating-characteristic curve of 0.935, a sensitivity of 85% and a specificity of 88%.
Conclusions: P-wave duration and amplitude show significant correlations with LVA size and may be used as a noninvasive tool to predict severe scarring. Amplitudes in lead I smaller than 0.062 mV were found to be predictive of LVA >35%.
Keywords: 12-lead surface ECG; Atrial fibrillation; Catheter ablation; Left atrial scarring.
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