Low atrial fibrillatory rate predicts poor outcome in heart failure

Low atrial fibrillatory rate predicts poor outcome in heart failure

Low atrial fibrillatory rate may indicate poor outcome in heart failure. A study by Platonov PG and colleagues had evaluated the role of atrial fibrillatory rate in predicting the outcome in mild to moderate heart failure [1]. Atrial fibrillatory rate is a measure of the atrial remodeling due to atrial fibrillation, which is both electrical and mechanical. Acceleration of atrial fibrillatory rate has been associated with longer duration of arrhythmic episodes. Faster atrial fibrillatory rate have been associated with poor outcome in electrical therapy of atrial fibrillation like cardioversion and catheter ablation of persistent atrial fibrillation in those without structural heart disease.

The investigators analyzed high resolution 20 minute Holter electrocardiograms from 169 patients with congestive heart failure. Estimation of atrial fibrillatory rate was done using spatiotemporal QRST cancellation and time frequency analysis. Mean follow up period was 44 months and total mortality was the primary end point. Sudden death and heart failure death were secondary endpoints. Authors concluded that a reduced atrial fibrillatory rate was associated with higher risk of death due to the progression of heart failure and could be a predictor of poor outcome.

Slower atrial fibrillatory rate could indicate a combination one or more of these factors:

• Reduced firing of focal atrial fibrillation sources
• Lower number of circulating wavelets
• Increase in atrial refractory period
• Slowing of atrial conduction (e.g. age related slowing of atrial conduction can lead to slower atrial fibrillatory rates)

Reference

1. Platonov PG, Cygankiewicz I, Stridh M, Holmqvist F, Vazquez R, Bayes-Genis A, McNitt S, Zareba W, de Luna AB; MUSIC Trial Investigators. Low Atrial Fibrillatory Rate Is Associated with Poor Outcome in Patients with Mild to Moderate Heart Failure. Circ Arrhythm Electrophysiol. 2012;5:77-83.