Objective To evaluate the predictive value of the maximum(Pmax) and minimum(Pmin) P-wave durations for paroxysmal atrial fibrillation(PAF).Methods Ninety consecutive inpatients with heart diseases who underwent 12-lead Holter monitoring during the period of January 2008 to October 2008 were retrospectively collected.There were 32 patients with PAF and 58 with non-atrial fibrillation(NAF).The Pmax,Pmin and clinical characteristics were compared between the two groups.Results The Pmax and average 24-h heart rate were significantly higher in PAF group than in NAF group((114±15)vs(104±11) ms,P<0.01;(89±25) vs(74±15) beats/min,P<0.01).There was no significant difference in Pmin between PAF and NAF groups.After adjustment for other covariates,it was shown that higher Pmax and average ventricular heart rate were the independent risk factors of PAF in inpatients with heart diseases.Conclusion Higher Pmax and average ventricular heart rate in 12-lead Holter monitoring are reliable predictors for the risk of PAF in inpatients with heart disease.