Aggressiv rytmkontroll ger ej ökad dödlighet och ej fler stroke:
=>Rate versus Rhythm Control
The RACE1, 2 and AFFIRM3 studies demonstrate rhythm-control has no survival benefit over rate-control. It is prudent to purse rate control in the acute setting since it is contraindicated to cardiovert stable patients with AF >48 hours or unknown duration without anticoagulation. Therefore, for stable patients without pre-excitation, intravenous BB or CCB are recommended to slow rapid AF.1
=>β-Blocker (BB) versus Nondihydropyridine Calcium Channel Blocker (CCB)
Between a BB and CCB, which is the best medication? The decision often encompasses multiple factors including contraindications, physician comfort, home medications, pharmacodynamics, etc.
In regards to home medications, it may benefit patients to continue the same class of home medication. Mixing BB and CCB, although sometimes necessary for rate control, may act synergistically potentiating AV nodal blockade, bradycardia, and hypotension. 1
- β 1 (80% cardiac β receptors) receptor stimulation
- Increases inotropy and chronotropy
- β 2 receptor stimulation
- Increases inotropy, relaxation, and chronotropy
- Mediates bronchodilation
- Decreases systemic vascular resistance
- Mechanism: Blocks β -adrenergic stimulation
- β 1 selective antagonist – decrease inotropy and chronotropy
- T1/2 3-4 hours
- Oral formulation both short and long acting
- T1/2 5-9 hours
- Oral formulation
- Additional: Acebutolol, Betaxolol, Bisoprolol, Celiprolol, Nebivolol
- Active wheeze in reactive airway disease (asthma, COPD) – Although β 1-blockers are cardioselective, studies demonstrate they decrease FEV1 and PEFR. Therefore BB should be used with caution in severe or active reactive airway disease.17, 18
- Known II or III degree AV block – BB or CCB may cause II or III degree AV block in 15% of patients.
Non-dihydropyridine Calcium Channel Blocker19
- 4 classes of CCBs, but nondihydropyridines have the greatest affinity for myocardial calcium channels
- Mechanism: Impedes calcium influx and channel recovery in the myocardium
- Inhibitory effect on SA and AV nodal tissue
- More potent negative inotrope > more profound side effect of hypotension8
- Fromm et al found diltiazem may provide superior rate control compared to metoprolol with no adverse events noted.
- Inclusion: ventricular rate ≥120 bpm, SBP ≥90 mmHg
- Exclusion: SBP <90mmHg, ventricular rate ≥220 bpm, QRS >0.100s, 2nd or 3rd AV block, STEMI, NYHA Class IV HF, active wheezing with history of asthma/COPD, anemia (hemoglobin <11 g/dL), pregnancy.
DO consider amiodarone in critically ill patients. DON’T use amiodarone in AF >48 h or unknown duration without anticoagulation.
- Class III antiarrhythmic
- Use in chemical cardioversion
- Sodium and potassium channel blocking properties
- β -blocking and calcium channel blocking properties => slows conduction through the AV node.
- Considerations: Amiodarone is an anti-arrhythmic, therefore in cases of AF or flutter >48h of unknown duration there is a possibility of cardioversion and risk of stroke.
- Pulmonary, hepatic, and thyroid toxicity. 1
MÅL med rate Control
Asymptomatic/hemodynamically stable: <110 bpm
Symptomatic: Rate to point of asymptomatic
=>Electrical Cardioversion (Unstable AF): DO cardiovert unstable AF.
Patients with hemodynamic instability, ongoing ischemia, or worsening heart failure should undergo direct current cardioversion. TEE först för att utesluta proppar i förmaksöron.
Managing Atrial Fibrillation Secondary to…
=>Sepsis: Do use BBs
AF is an independent predictor of mortality the critically ill, AF confers 31% mortality versus patients without AF at 17% mortality (P<0.001).30 A retrospective cohort by Walkey et al of 39,693 septic patients with AF analyzed practice patterns and mortality. CCBs were most commonly initiated in AF during sepsis (36%); however, BBs were associated with lower hospital mortality compared to CCB (RR 0.92), digoxin (R 0.79), and amiodarone (RR 0.64).31
=>Hyperthyroid: Do use BBs
BBs are recommended to control AF complicating thyrotoxicosis unless contraindicated (Level C).4 The rationale is two-fold, first hyperthyroidism is a state of increased β -adrenergic receptors thus BB reduce symptoms.32 Second, propranolol, atenolol, and metoprolol slowly decrease serum T3 concentrations by inhibiting the conversion from thyroxine (T4).33, 34
=>Heart Failure: Do use BBs
The AF-CHF study by Dydra et al compared rate versus rhythm control strategies in CHF. The study enrolled 1,376 patients with an EF <35% and recent history of AF, patients were randomized to rate control utilizing BB or rhythm control utilizing electrical cardioversion and amiodarone. Rhythm control was abandoned more frequently than rate control, 21% versus 9.1% respectively. The predominant reason to abandon rate control was worsening heart failure. Importantly, crossover from rhythm to rate control did not increase cardiovascular or all cause mortality.35 Although rate control is an acceptable strategy in CHF, BB therapy does not confer the same mortality benefit in AF as it does in sinus rhythm.36 Therefore, BB can be used in HF but does not need to be the only or first line agent.
The decrease in SVR, anti-ischemic effects, and LV relaxation of CCBs indicate theoretical benefit in CHF. However, the negative inotropic effect may impair left ventricular function.37 Furthermore, the MDPIT study by Goldstein et al showed post-MI patients on CCBs with early LV dysfunction (EF <40%) were found to have increased late onset heart failure.21 Although the evidence is not overwhelming, in cases of rapid AF and CHF, particularly decompensated HF, rate control with CCBs can be detrimental.