Anticoagulation for people presenting acutely with atrial fibrillation 1.8.8 In people with new-onset atrial fibrillation who are receiving no, or subtherapeutic, anticoagulation therapy: in the absence of contraindications, offer heparin at initial presentation continue heparin until a full assessment has been made and appropriate antithrombotic therapy has been started, based on risk stratification (see section 1.2 on assessment of stroke and bleeding risks and section 1.6 on stroke prevention). [2006, amended 2014] 1.8.9 In people with a confirmed diagnosis of atrial fibrillation of recent onset (less than 48 hours since onset), offer oral anticoagulation if: stable sinus rhythm is not successfully restored within the same 48-hour period after onset of atrial fibrillation or there are factors indicating a high risk of atrial fibrillation recurrence, including history of failed cardioversion, structural heart disease, prolonged atrial fibrillation (more than 12 months), or previous recurrences or it is recommended in section 1.2 on assessment of stroke and bleeding risks and section 1.6 on stroke prevention. [2006, amended 2014] 1.8.10 In people with new-onset atrial fibrillation, if there is uncertainty over the precise time since onset, offer oral anticoagulation as for persistent atrial fibrillation (see section 1.2 on assessment of stroke and bleeding risks and section 1.6 stroke prevention). [2006, amended 2014] 1.9 Initial management of stroke and atrial fibrillation 1.9.1 For guidance on the initial management of stroke and atrial fibrillation see recommendation 1.4.17 in NICE's guideline on stroke and transient ischaemic attack in over 16s. [2014] 1.10 Preventing and managing postoperative atrial fibrillation Preventing postoperative atrial fibrillation 1.10.1 In people having cardiothoracic surgery: reduce the risk of postoperative atrial fibrillation by offering 1 of the following: amiodarone a standard beta-blocker (that is, a beta-blocker other than sotalol) a rate-limiting calcium-channel blocker (diltiazem or verapamil) do not offer digoxin. 