Purpose: Catheter ablation (CA) is the treatment of choice of symptomatic drug-refractory atrial fibrillation (AF). Multiple factors including age, left atrial (LA) dilation, type of AF and hypertension (HT) are predictive of AF recurrence following CA. The P-wave duration as a global index of atrial activation and remodeling, however, has not been tested so far. The objectives of our study are 1) to identify the parameters that determine the duration of the pre-ablation ECG P-wave and 2) to determine whether long term success can be predicted by the kinetics of the P-wave duration following CA.Method: 108 consecutive patients (pts, age 56±9y) underwent a mean of 1.4 CA for drug-refractory AF (duration 7±8y, paroxysmal 58%, persistent 42% (pers-AF)). The P-wave duration was averaged over three consecutive beats from the pre-ablation ECG by a single investigator blinded to AF type and results of CA. Comparisons between groups were performed using unpaired studentʼs t-test. Linear regression was used to assess the correlation between the P-wave duration and continuous variables (age, BMI, height, NT-proBNP, LA volume). p<0.05 was considered significant.Results: The table below reports parameters that were significantly associated (p<0.05) with the P-wave duration. In contrast, sleep apnea syndrome and diabetes did not prolong the P-wave. Linear regression showed the absence of correlation between the P-wave duration and age, BMI, NT-proBNP level and LA volume (by Carto-XP, Webster). P-wave duration, however, was negatively and weakly correlated to patientsʼ height (R2=0.091, p<0.05).Conclusions: Our study shows that HT, dyslipidemia, CHADS2 score ≥1 and pers-AF contribute to the remodeling process (i.e. 2nd factor) leading to the prolongation of the ECG P-wave in pts referred for CA. These findings suggest that multiple co-morbidities may oppose the long term benefit of pulmonary vein isolation. (Table is included in full-text article.)