Subclinical Postoperative Atrial Fibrillation

Clinical background:

Postoperative atrial fibrillation and atrial flutter (POAF) is the most common complication after cardiac surgery requiring intervention or prolonged hospital stay . Affecting 10-65% of patients , this arrhythmia is associated with increased mortality, considerable morbidity including systemic therombo-embolism and hemodynamic deterioration. Often it will prolong the hospital stay and increase health costs. Notably, the incidences of POAF is increasing resulting from an increase in the average age and arrhythmic risk factors in patients undergoing cardiac surgery.

Although a lot of POAFs occur in patients with a history of PAF, there is an important portion of POAF in patients who have never experienced AF before. In some of these patients POAF may be the first manifestation of a tendency to fibrillate (that may have been silent prior to surgery) whereas in others it may be an acute response to the peri-operative stress that may never recur after the acute phase. A recent study has shown that patients with a first detected AF episode precipitated by a secondary event (the most common of which was cardiothoracic surgery) are very likely to have recurrent events. In fact the risk of recurrence was similar to that of patients with an AF event with an obvious precipitating factor Current guidelines mainly address the acute management of arrhythmia. Most conclude that anti-thrombotic therapy is indicated in POAF (IIA) usually if the arrhythmia persists for at least 48 hours. However this recommendation is based on very limited evidence as there is no substantial data describing the long term natural history of this complication. POAF was described as self-terminating but frequently recurrent with a complete resolution within 6-12 weeks . However, this observation was based on electrocardiogram follow-up with no continuous long term monitoring (ECG holter or loop recorder) and are therefore of limited validity. Emerging data suggests that AF recurrence rates may be significate ranging up to 24% over 6 years . Still, it is currently unknown how many of the patients presenting with an acute episode of POAF will develop recurrent events and when, as a result, there are no clear recommendations regarding the duration of anticoagulantion treatment. The current practice in cases of POAF of significant duration is to administer anti-coagulation therapy combined with antiarrhythmic (most often with amiodarone) for 6-12 weeks. The only guideline based recommendation that is based on poor evidence is to administer OAC to AF patients following CABG for at least 3 months . Holter ECG is routinely performed prior to the end of this period and if normal and clinical evaluation is normal the treatment is discontinued, usually with no additional evaluation.

Technical overview:

This study will be executed using the following devices and services: