Background: To find out the real-world investigation on discontinuation of oral anticoagulation after paroxysmal atrial fibrillation (AF) catheter ablation China. Methods:We enrolled in our study 1,508 consecutive paroxysmal AF patients who underwent catheter ablation from five centers. Patients' clinical data and follow-up data were collected. Clinical data included on-admission characteristics such as gender, age, type and duration of AF, type of ablation, ablation sessions, history of diseases, CHA 2 DS 2 -VASc score, echocardiographic variables, medication, and blood test variables.Follow-up data included duration of follow-up, the status of oral anticoagulant (OAC) therapy, adverse events, and recurrence of AF.Results: A total of 1,491 patients were included in the final analysis, while the other 17 patients lost contact. The follow-up duration was 12 to 74 months (27.8±14.6 months). Of 1,491 patients, 989 (66.3%) patients stopped OAC therapy 3 to 14 months after successful ablation during follow-up. Stroke or transient ischemic attack (TIA) occurred in 37 (2.5%) patients. Major bleeding occurred in 24 (1.6%) patients. Six (0.4%) patients died at follow-up. Patients who stopped OAC had lower CHA2DS2-VASc score (1.5±1.4 vs. 2.4±1.7, P<0.05) and lower incidence of major bleeding (11/989 vs. 13/502, P<0.05). Of 989 patients who stopped OAC, 318 stopped according to doctor's prescription, and 671 stopped on their own decision.In patients who underwent brain MRI, patients who stopped OAC had a lower incidence of silent cerebral infarction (SCI) (37/904 vs. 38/419, P<0.05). Among patients who did not stop warfarin therapy, there were 117 (117/397, 29.5%) patients had not to achieve target INR. Conclusions:The incidence of adverse events was relatively low in paroxysmal AF patients who stopped OAC. The patient partly determined when OAC was discontinued. Target INR was not achieved in many patients who had not to stop OAC.

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Phe58 of cytochrome b5 is involved in stacking interactions with heme and the axial ligand His63. To elucidate the contribution of the stacking interactions to protein stability, the crystal structures of the F58Y and F58W mutants were determined at high resolution. The structure of the F58Y mutant is basically the same as that of the wild-type protein. However, the mutation from Phe58 to Trp58 leads to difficulty in growing single crystals and results in a space-group change; the six molecules in the asymmetric unit form two groups that are related by a non-crystallographic twofold axis. The structure of F58W was determined using molecular replacement by making use of the non-crystallographic symmetry. The F58W mutation gives rise to multiple conformations of six side chains, a peptide linking two of the six residues and the extended propionic acid of the heme. The six molecules in the asymmetric unit of the F58W mutant structure are grouped into two types based on their conformations and one of the six molecules exhibits dual conformations. The stacking interactions are weakened owing to the increase/decrease of the angles between the indole ring of Trp58 and the His63/heme rings, which accounts for the lower stability of F58W compared with the wild-type protein.