Objective To assess the prediction value of Pmax and Pd on idiopathic paroxysmal atrial fibrillation(IPAF) and the possible mechanism of amiodrone preventing the recurrence of IPAF.Methods Pmax and Pd were measured in 60 patients with IPAF and 60 healthy control subjects by 12-lead surface electrocardiography. 30 of patients with IPAF were assigned to treatment with amiodrone for 6 months. Pd?Pmax and recurrence of IPAF were observed and compared with control group during the treatment.Results Pmax and Pd were found to be significantly higher in patients with IPAF than in healthy subjects[(126?17)ms vs(102?11)ms; (50?9)vs(29?8)ms,P