Post-operative Atrial Fibrillation - Pathophysiology, Treatment and Prevention

Abstract

Atrial fibrillation occurring after cardiac surgery has been the subject of intensive research over the past decades. However, the incidence remains high, despite numerous preventive and treatment strategies. In addition, several reports show that the impact of post-operative atrial fibrillation (POAF) is high. It is an independent risk factor for mortality after several years. These findings make clear that the pathophysiology of POAF is not fully understood and POAF-associated risks to some extent might be underestimated. On the one hand, excessive triggers during the acute post operative phase after cardiac surgery might initiate AF even in atria with low vulnerability. On the other hand, many patients undergoing surgery have an atrial substrate at the time of operation promoting AF not only in the post-operative phase but also in the days and weeks thereafter. Progress in our understanding of the AF mechanisms in general has provided valuable insights into processes involved in atrial structural remodeling due to advanced age, hypertension, obesity, and congestive heart failure. These patient characteristics strongly contribute to cardiac disease, predict POAF and likely have an impact on the risk of thrombus formation in the weeks and months after cardiac surgery. For a better understanding of the mechanisms involved, it is important to not only recognize the occurrence of POAF by continuous monitoring after surgery, but also to identity the extent of atrial vulnerability to AF in these patients.

Figure 1.. A schematic sketch of incidence of POAF in the early post-operative phase (i.e. the first post-operative week) and during the late post-operative phase (i.e. weeks to years following cardiac surgery) after discharge. In severely aggravated atrial substrates, POAF might continue to exist and reoccur. Red area under the curve represents patients with a preexistent structural substrate, e.g. atrial enlargement or heart failure, which is not easily reversible. White area under the curve represents patients with less severe structural substrate but who are exposed to the pro-arrhythmic environment of the acute-postoperative phase