The association between atrial fibrillation and heart failure has been well established. Although the causal relationship between the two clinical entities has not been fully elucidated, atrial fibrillation is believed to cause heart failure via several mechanisms: 1) increased heart rate resulting in shorter diastolic filling time and lower cardiac output; 2) reduced atrial contraction contribution to left ventricular filling, lowering cardiac output; and 3) tachycardia-induced cardiomyopathy from myocardial ischemia, myocardial energy depletion, and abnormal calcium regulation leading to left ventricular dilatation and reduced ejection fraction. These processes occur over time. It is also established that the left atrial appendage is a source of atrial natriuretic peptide, and it has been hypothesized that removal of the appendage might impair renal clearance of salt and water, increasing the risk of heart failure. A recent non-randomized study has supported this hypothesis. In LAAOS III, we did not observe an increase in hospitalization for heart failure, either early after surgery or during the 3.8 years of follow-up. However, an adverse impact on heart failure may appear over a longer follow-up period. We need to ensure we examine this patient population for the long-term impact of left atrial appendage occlusion on heart failure hospitalization to ensure we fully appreciate the benefit-risk balance of this intervention.~The extended follow-up of the LAAOS III trial aims to assess whether, in patients with a history of atrial fibrillation undergoing cardiac surgery for another indication, concomitant left atrial appendage occlusion decreases the risk of death and stroke on top of usual care including anticoagulation without increasing re-hospitalization for heart failure at a mean follow-up of 8 years.
LAAOS III Extension is a longer term follow-up of an international cohort study of patients who were enrolled in the Left Atrial Appendage Occlusion Study (LAAOS III) trial.