Postoperative AF after cardiac surgery

Postoperative AF after cardiac surgery

Postoperative atrial fibrillation (AF) is one of the most common complications after cardiac surgery. The occurrence of postoperative atrial fibrillation is rising as more and more older patients are undergoing cardiac surgery. It may occur in up to one third of post cardiac surgical patients. Over one hundred trials have evaluated postoperative atrial fibrillation and many meta analyses have been conducted on these trials. Atrial fibrillation can occur both after coronary artery bypass grafting and surgery for valvular heart disease. The onset of atrial fibrillation would mean longer stay in the intensive care unit and higher risk of postoperative stroke. The risk of stroke is enhanced two to four times with post operative atrial fibrillation [1]. In addition there is a chance for delirium and cognitive dysfunction in these cases.

Post operative AF after coronary artery bypass graft (CABG) surgery has been associated with both higher in hospital and long term mortality [2]. The study compared 994 patients who developed post CABG AF and 5481 who did not develop AF. Survival at 5 years was 87% in those who had postoperative AF while it was 93% in those did not have AF.

Several strategies have been employed in the prevention and treatment of postoperative atrial fibrillation. They include beta blockers, magnesium, sotalol, amiodarone, calcium channel blockers, digoxin and atrial overdrive pacing. Of the lot, digoxin appears to have least evidence in favour of it. Use of digoxin for prophylaxis against AF is a Class III recommendation as per 2014 AATS guidelines (not to be used for prophylaxis). Beta blocker withdrawal may increase the risk of postoperative atrial fibrillation. Continuation of betablockers is a Class I recommendation in 2014 AATS guidelines [3]. Sotalol appears to be more effective than conventional beta blockers in some studies. Various forms of atrial pacing used in the prevention of postoperative atrial fibrillation are right atrial pacing, biatrial pacing, left atrial pacing and Bachmann’s bundle pacing. Several trials have evaluated the role of pacing. But the overall results have not been very encouraging, though there was mild reduction in the incidence of postoperative atrial fibrillation.

Amiodarone has been evaluated in several trials with fair results. 2014 AATS guidelines gave a Class IIa recommendation for the use of amiodarone in postoperative AF [3]. They advised caution while selecting doses for intravenous or oral route because cases of ARDS had been reported following pneumonectomy with cumulative intravenous doses above 2150 mg [4].

Emergency synchronized cardioversion is needed in post-operative AF with hemodynamic instability (Class I recommendation). Betablockers and nondihydropyridine calcium channel blockers like diltiazem have a Class I indication for rate control in post operative atrial fibrillation. Caution is advised in those with left ventricular dysfunction, heart failure or hypotension[3]. Intravenous amiodarone has a Class IIa recommendation in these situations. As amiodarone has a potential for converting AF to sinus rhythm, if it is initiated after 48 hours of onset of AF, transesophageal echo to rule out left atrial/appendage thrombi and anticoagulation are to be considered if feasible [3].

References

1. Greenberg JW, Lancaster TS, Schuessler RB, Melby SJ. Postoperative atrial fibrillation following cardiac surgery: a persistent complication. Eur J Cardiothorac Surg. 2017 Oct 1;52(4):665-672.
2. Villareal RP, Hariharan R, Liu BC, Kar B, Lee VV, Elayda M, Lopez JA, Rasekh A, Wilson JM, Massumi A. Postoperative atrial fibrillation and mortality after coronary artery bypass surgery. J Am Coll Cardiol. 2004 Mar 3;43(5):742-8.
3. Frendl G, Sodickson AC, Chung MK, Waldo AL, Gersh BJ, Tisdale JE, Calkins H, Aranki S, Kaneko T, Cassivi S, Smith SC Jr, Darbar D, Wee JO, Waddell TK, Amar D, Adler D; American Association for Thoracic Surgery. 2014 AATS guidelines for the prevention and management of perioperative atrial fibrillation and flutter for thoracic surgical procedures. J Thorac Cardiovasc Surg. 2014 Sep;148(3):e153-93.
4. Van Mieghem W, Coolen L, Malysse I, Lacquet LM, Deneffe GJ, Demedts MG. Amiodarone and the development of ARDS after lung surgery. Chest. 1994 Jun;105(6):1642-5.