There are no new recommendations on the use of drugs for acute rate and rhythm control, but it is outlined that, after an adequate thrombo-embolic risk management, the first step consists of good rate control and acute cardioversion (pharmacological or with DCC shock) is only proposed in particular situations. For direct current cardioversion it is recommended to use biphasic external defibrillators with an antero-posterior electrode placement and with pre-treatment by antiarrhythmic drugs such as amiodarone, ibutilide, sotalol, flecainide, and propafenone.
The objectives of long-term management are: prevention of thrombo-embolism, symptoms relief, optimal management of concomitant cardiovascular disease, rate control, and correction of rhythm disturbance. An important statement of the guidelines is the concept that the strategy of the treatment may vary during time if the results of the therapy are not satisfying. Guidelines compare rate control with rhythm control and no differences in the clinical outcome, symptoms, occurrence of heart failure and quality of life of patients with AF assigned to rhythm vs. rate control strategies can be found in the literature. Only the ATHENA trial with dronedarone demonstrated a significant effect of the therapy on mortality and hospitalization.
Adequate long-term rate control improve symptoms and haemodynamics, but while previous guidelines recommended strict rate control (resting heart rate between 60–80 bpm and 90–115 bpm during moderate exercise), new guidelines state that in patients without severe symptoms due to a high ventricular rate, a lenient rate (resting heart rate <110 bpm) control therapy approach is reasonable. The drugs to achieve rate control are the same as in previous guidelines, but also the new antiarrhythmic drug Dronedarone may reduce heart rate and may be useful in particular situations.
Ablation of the atrioventricular node may be acceptable when pharmacological rate control is impossible or rhythm control has failed in highly symptomatic patients.
The statement of the new guidelines that asymptomatic patients have not to take antiarrhythmic drugs and that rhythm control therapy is limited to the relief of AF-related symptoms is strong and very important.
The guidelines outline the concept of choosing an antiarrhythmic drug that is safer, although possibly less efficacious, before a more effective one but less safe. It is the first time that dronedarone is considered in guidelines for AF treatment: Dronedarone shows an efficacy to maintain sinus rhythm lower than that of amiodarone, but has also less toxic effects and in the ATHENA study there was a not significant reduction in deaths in the dronedarone group and a significant reduction of cardiovascular mortality, due to a reduction in stroke risk independent of antithrombotic therapy.
Between amiodarone and dronedarone, dronedarone may be the first option, at least in symptomatic AF and underlying cardiovascular disease and, if it fails to control symptoms, amiodarone could be necessary, although its general toxicity is considerable mainly when used at higher doses. Only subjects with NYHA class III or IV, or recently unstable heart failure, should not receive dronedarone. Guidelines outline a new therapeutic paradigm in patients with AF: the prevention of repeated hospitalizations that can be more important to patient and physician compared with sinus rhythm maintenance per se.
The new guidelines consider indicated left atrial catheter ablation in a paroxysmal AF patient very symptomatic despite optimal medical therapy. Some points to take into account are: the stage of atrial disease, the underlying cardiovascular disease, potential alternatives (antiarrhythmic drugs, rate control), patient preference, operator-dependence of the ablation procedures.
The guidelines are not so defined for ablation in patients with either persistent AF or long-standing persistent AF and no or minimal organic heart disease, with organic heart disease with associated major symptoms, and in patients with heart failure. Patient age, organic heart disease, LA size, co-morbidities, and patient preference have to be considered.
During surgical procedures such as mitral repair, restoration of sinus rhythm with surgical ablation improves outcome and predicts late adverse cardiac events and stroke.
In the guidelines upstream therapy appears for the first time. It is aimed to prevent or delay myocardial remodelling of hypertension, heart failure, or inflammation and may delay the development of new AF (primary prevention) or the progression to permanent AF (secondary prevention). The classes of drugs considered for upstream therapy are:
- Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers
- Aldosterone antagonists
- Polyunsaturated fatty acids.
Chapter 5 – Specific Populations
Heart failure can create a substrate or to be a trigger for AF, while AF is a strong and independent risk factor for heart failure. No clear demonstration of superiority of rhythm control strategy versus rate control in heart failure patients with AF have been shown, although catheter-based LA ablation procedures may lead to clinic and LV function improvement.
In athletes rate control may be difficult because beta-blockers are often not well tolerated or are prohibited. Sports can be played if the heart rate is good at maximal physical performance.
In patients with valvular heart disease a rate control strategy is usually preferred because of the low likelihood of maintaining sinus rhythm in the long term.
Urgent DCC may be considered in acute coronary syndromes AF patients with ischaemia or haemodynamic instability. Beta-blocker or non-dihydropyridine calcium antagonist therapy is indicated for rate control. Digoxin and/or i.v. amiodarone are appropriate in patients with ACS and severe LV dysfunction and heart failure.
AF and Diabetes mellitus frequently co-exist conferring an adverse prognosis with an increase in death and cardiovascular events. A comprehensive risk management is mandatory.
Due to the high prevalence of AF in the elderly (~10% at the age of 80 years) the opportunistic screening by the general practitioner, followed by an ECG when the pulse is irregular, is effective in diagnosing AF.
In patients with previously diagnosed AF, many experience recurrences during pregnancy. Caution should be given for the use of beta-blockers, amiodarone and digoxin for foetal toxicity. Cardioversion of maternal AF seems to be safe for the foetus.
The prevention of post-operative atrial fibrillation can be obtained by beta-blocker therapy and by amiodarone. Haemodynamically stable patients will convert spontaneously to sinus rhythm within 24h. Management includes correction of predisposing factors, DCC cardioversion in highly symptomatic patients and pharmacological cardioversion. Anticoagulation with heparin or VKA is appropriate when AF persists longer than 48h.
In patients with hyperthyroidism the first treatment is aimed to restore a euthyroid state, and thyroid function must be normalized prior to cardioversion.
Patients with Wolff–Parkinson–White syndrome and with hypertrophic cardiomyopathy have many specific features in the risk of sudden death and in the indication for drug therapy or ablation.
AF is common in patients with pulmonary disease more often during acute exacerbations associated with hypoxia. Antiarrhythmic therapy is frequently ineffective until respiratory decompensation has been corrected.
END OF PART 2