Findings to the investigation revealed that:
Therapeutic goals in patients with atrial fibrillation Rate versus rhythm control There is still no consensus regarding whether patients with persistent AF are best managed using strategies that target the arrhythmia itself, or those that accept the arrhythmia and control the ventricular rate.
With rate control strategies, the arrhythmia is allowed to continue, and symptomatic improvement is achieved solely because of better control of the ventricular rate. As the atria continue to fibrillate, the risk of thromboembolism persists and ventricular filling occurs only passively, without the active contribution of atrial contraction.
Rhythm control, on the other hand, aims to restore sinus rhythm and thus synchronised atrioventricular contraction. In theory, this strategy should also help slow or prevent the progression to permanent AF and reduce the risk of thromboembolism, although there is as yet no evidence to support the latter assumption.
Another important consideration, however, is the propensity for drugs used for rhythm control to cause serious proarrhythmia.
In a randomised open label pilot trial comparing rate control, predominantly using diltiazem, and rhythm control, predominantly using amiodarone with or without direct current DC cardioversion in patients with AF, the two strategies produced similar improvements in quality of life.
However, hospital admissions, predominantly for DC cardioversions, were higher in the rhythm control group. Enrolled patients mean age 70 years had at least one risk factor for stroke or death accompanying AF and could symptomatically tolerate the arrhythmia at baseline. The primary end point of the study, all cause mortality, was not significantly different between the two groups, although there was a trend favouring rate control.
There were also no differences in secondary end point components, including stroke rate, quality of life, or functional status and, although a trend favouring rate control was once again noted, anticoagulation was discontinued in more patients in the rhythm than in the rate control group.
Atrial fibrillation causes pathophysiology and treatment essay majority of strokes in both groups occurred in patients with subtherapeutic levels of anticoagulation, or after warfarin had been stopped.
In the pre-defined group of patients who were under the age of 65, which accounted for approximately a quarter of patients included in the study, a trend favouring rhythm control was noted.
These results suggest that, at least in this elderly population of patients with AF and risk factors for stroke or death, rate control is at least as good as rhythm control. It should, however, be emphasised that these conclusions are not necessarily applicable to different patient populations, including younger patients with structurally normal hearts, or patients who are unable to tolerate the arrhythmia despite reasonable rate control.
The results of AFFIRM also appear to be at odds with the results of a DIAMOND Danish investigations of arrhythmia and mortality on dofetilide substudy, in which patients mean age 72 years with heart failure or recent myocardial infarction and AF had been randomised to treatment with dofetilide or placebo.
In this study, dofetilide was shown to be moderately effective at restoring sinus rhythm, but had no demonstrable effect on mortality. However, in a multivariate model, restoration of sinus rhythm, regardless of whether this was achieved pharmacologically, spontaneously, or electrically, was associated with a notable reduction in mortality.
It has been demonstrated that restoration of sinus rhythm is associated with improvements in exercise capacity and peak oxygen consumption, both in patients with structural heart disease and in those with normal hearts.
For patients who have been in AF for longer, or in whom the duration of the arrhythmia is not clear, a minimum period of anticoagulation of three weeks is recommended before cardioversion. However, even if transoesophageal echocardiography has demonstrated no thrombus before cardioversion, patients must be anticoagulated for at least one month after cardioversion, since mechanical atrial function may return slowly after cardioversion.
Pharmacological cardioversion is often possible for the treatment of AF of recent onset, but efficacy is dramatically reduced in patients with AF that persists for more than 48 hours.
Flecainide also appears to be superior to both propafenone and amiodarone in this setting. Pharmacological cardioversion is much less likely to be effective when AF has persisted for more than 48 hours.
However, because of a significant risk of proarrhythmia, treatment must be initiated during continuous monitoring in hospital.
Sinus rhythm maintenance Flecainide and propafenone have been shown to be similarly effective at suppressing symptomatic paroxysms of AF and, in the absence of structural heart disease, neither drug appears to cause significant proarrhythmia.
In general, these class Ic agents tend to be better tolerated and more effective than class Ia agents, such as quinidine and disopyramide.
Digoxin administration does not alter the probability of restoration or maintenance of sinus rhythm in patients with AF of recent onset. Sotalol may be better than propafenone at preventing AF paroxysms.
In a direct comparison, amiodarone has more recently been shown to be superior to both propafenone and sotalol at maintaining sinus rhythm. Principles of AF management: Although generally safe to use even in patients with poor ventricular function, it appears to be less effective than other agents at controlling ventricular rate, particularly during acute or paroxysmal AF, exercise, or critical illnesses.
The efficacy of digoxin at controlling the ventricular rate in AF is also limited during acute paroxysms of AF, and use of the drug may prolong the duration of paroxysms.
Both diltiazem and verapamil are superior to digoxin at controlling ventricular rates during exercise and allow modest improvements in exercise capacity, without causing resting bradycardia or pauses.
In patients with impaired ventricular function, chronic administration of amiodarone, in addition to reducing AF burden, significantly reduces the ventricular rate.
Intravenous amiodarone may also be moderately effective at controlling the ventricular rate in critically ill patients with AF. Common mistakes Anticoagulation In clinical practice, physicians are often less keen to prescribe anticoagulation for patients with paroxysmal AF than for those with persistent AF.
Although the risk of thromboembolism may indeed be higher in patients with persistent AF, thromboembolic risk may be substantial even in patients with paroxysmal AF.
Therefore decisions regarding anticoagulation should be predominantly based on the presence or absence of well established risk factors for thromboembolism, including previous stroke or transient ischaemic attack, valvar or other structural heart disease, hypertension, diabetes, age more than 65 years, and echocardiographic parameters such as left ventricular function and left atrial size, rather than on the temporal pattern of the disease.
Rate control It is common for physicians to prescribe digoxin alone in attempts to control the ventricular response to AF.
Rhythm control It is also common for physicians to prescribe digoxin to cardiovert patients. Digoxin has no effect on the likelihood of cardioversion, whereas class I antiarrhythmic drugs or amiodarone are often effective.
Because of the limited efficacy of catheter based treatments, especially for patients with persistent AF, and the substantial morbidity and mortality associated with surgery for the arrhythmia, pharmacological therapy remains the mainstay of treatment for the majority of patients.Atrial Fibrillation a stroke.
Atrial fibrillation can also lead to heart failure or heart attack (Waktare, ). What causes atrial fibrillation?
Nov 13, · Atrial fibrillation is the most common chronic arrhythmia, characterized by erratic atrial electrical activity with atrial rates of to beats per minute. The P wave is absent on the surface. Atrial fibrillation is the most common form of cardiac arrhythmia; it involves the two upper chambers of the heart known as the atria.
Sep 10, · Words: Length: 4 Pages Document Type: Essay Paper #: Atrial Fibrillation Simply stated, atrial fibrillation describes a condition in which the human heart beats at an excessively rapid rate that can result in diminished blood flow to the body.
Atrial Fibrillation Pathophysiology March 20, Introduction Atrial Fibrillation, commonly known as A-Fib or AF, is the most common type of persistent cardiac arrhythmia.
AF effects only 2% of the population under the age of 65, but 9% of those over the age of 65 (Centers for Disease Control and Prevention [CDC], ). ACC/AHA/ESC guidelines for the management of patients with atrial fibrillation: executive summary a report of the American College of Cardiology/American Heart Association task force on practice guidelines and the European Society of Cardiology committee for practice guidelines and policy conferences (committee to develop guidelines for the management of patients with atrial fibrillation) .