Atrial Fibrillation
Atrial Fibrillation in the Failing Heart – A Clinical Review
Lori L McMullan, Gaston Vergara and Nassir F Marrouche
Comprehensive Arrhythmia Research and Management Center, Division of Cardiology, School of Medicine, University of Utah
Abstract
Not only are atrial fibrillation (AF) and heart failure (HF) the most commonly encountered disease conditions in clinical practice, they are also associated with an increased risk of both morbidity and mortality. Both diseases are affiliated with maladaptive neurohormonal changes and remodelling of the heart. Treatment of AF has focused on prevention of thromboembolism, rate control and rhythm maintenance. Rhythm maintenance with anti-arrhythmic drugs has been relatively ineffective in maintaining patients in sinus rhythm, with the addition of increased adverse side effects. Rhythm control of AF via catheter radiofrequency ablation is a viable treatment option, with several studies showing improvement in ejection fraction, quality of life and the six-minute-walk test. Future multicentre randomised controlled trials are pending, the first being Catheter Ablation Versus Standard Conventional Treatment in Patients With Left Ventricular Dysfunction and Atrial Fibrillation (CASTLE-AF), to determine whether catheter ablation of AF is superior to conventional therapy for patients suffering from AF and HF.
Keywords
Atrial fibrillation, congestive heart failure, atrial remodelling, anti-arrhythmic drugs, catheter ablation, magnetic resonance imaging (MRI), ventricular dysfunction
nassir.marrouche@hsc.utah.edu
Atrial fibrillation (AF) and heart failure (HF) are two disease conditions that are intimately intertwined, both pathophysiologically and clinically. Currently, over 2.3 million people in North America and 4.5 million in the EU have AF, making it the most common arrhythmia encountered in clinical practice.1,2 be over 10 million people with AF.3 the US is 5.3 million.4
It is expected that by 2050 there will The estimated prevalence of HF in
other, and the prevalence of both increases as the patient ages.4
Each condition increases the prevalence of the Even
when adjusting for age, the prevalence of both AF and HF is increasing. The prevalence of AF also increases with the degree of heart failure. Up to 50% of patients with New York Heart Association (NYHA) functional class IV had AF, whereas only 5% of patients with NYHA I had AF.4
five-fold increased risk of developing AF.5
morbidity and mortality and have been a major healthcare focus, especially in the ageing population.
Current management of AF has focused on rhythm versus rate control. Studies have evaluated this management strategy in HF patients and have concluded there is no difference with either strategy.6
Unfortunately, only 50% of the rhythm control patients
remained in normal sinus. There was also an increase in adverse side effects with anti-arrhythmic drugs (AADs), which may have negated the positive effects of normal sinus rhythm.7
Catheter ablation of AF shows promise in patients with HF. Recent studies have shown
© T O UCH BRIEFINGS 2010
improvement in NYHA class, quality of life measurements, left ventricular (LV) function and the six-minute-walk test (6MWT) after AF ablation, even compared with biventricular pacing after an atrioventricular (AV) nodal ablation.8–13
In this article, we will review: remodelling of the heart in AF and congestive HF (CHF); advantages of sinus rhythm; the current treatment options for AF in patients with HF, in particular the role of catheter ablation; staging patients with LV dysfunction; and the highly anticipated Catheter Ablation Versus Standard Conventional Treatment in Patients With Left Ventricular Dysfunction and Atrial Fibrillation (CASTLE-AF) study.
In the Framingham study, HF was associated with a Both conditions increase
Structural Remodelling and Left Ventricular Function
Due to the inextricable link between AF and HF, both diseases cause maladaptive remodelling to the heart. The neurohormornal activation, volume and pressure overload of HF produce a milieu in which AF can be initiated and sustained. AF concomitantly promotes HF through loss of atrioventricular (AV) synchrony and a rapid irregular ventricular response.4,14
The electrical remodelling of the atria in patients with AF occurs as early as 24–48 hours.15
Allessie demonstrated that rapid atrial pacing of goats resulted in shortening of the atrial refractory period, a shorter
75
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92