Atrial fibrillation rate control
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Cafer Zorkun, M.D., Ph.D. [2]
Overview
Atrial fibrillation with rapid ventricular rate is a common finding in many hospitalized patients. The ventricular rate may be increased upto 150-170. It is essential to bring the ventricular rate down to less than 100 because a rapid ventricular response can cause hemodynamic instabilities and tachycardia mediated cardiomyopathies (heart failure). AF can cause disabling and annoying symptoms. Palpitations, angina, lassitude (weariness), and decreased exercise tolerance are related to rapid heart rate and inefficient cardiac output caused by AF. This can significantly increase mortality and morbidity, which can be prevented by early and adequate treatment of the AF.
Rate Control
Rate Control versus Rhythm Control
There are two ways to approach symptoms: rate control and rhythm control.
- Rate control treatments seek to reduce the heart rate to normal, usually 60 to 100 beats per minute.
- Rhythm control seeks to restore the normal heart rhythm, called normal sinus rhythm.
- Studies suggest that rhythm control is mainly a concern in newly diagnosed AF, while rate control is more important in the chronic phase.
- Rate control with anticoagulation is as effective a treatment as rhythm control in long term mortality studies, the AFFIRM Trial.[1]
- The AFFIRM study showed no difference in risk of stroke in patients who have converted to a normal rhythm with anti-arrhythmic treatment, compared to those who have only rate control.[1]
Pharmacologic Rate Control
Mechanism of Action
- Rate control is achieved with medications that work by increasing the degree of block at the AV node, effectively decreasing the number of impulses that conduct to the ventricles. This can be accomplished with:
- Calcium channel blockers (i.e. diltiazem or verapamil) block the influx of calcium and reduce the upstroke of the action potential.
- Beta blockers (preferably the cardioselective beta blockers such as metoprolol, atenolol, bisoprolol) slow conduction by decreasing sympathetic tone.
- Cardiac glycosides (i.e. digoxin) are vagomimetics and slow conduction by increasing parasympathetic effects on the node.
- Amiodarone has some AV node blocking effects, and can be used in individuals when other agents are contraindicated or ineffective (particularly due to hypotension).
- Adenosine slows conduction by increasing potassium conduction and decreasing calcium entry.
- Carotid massage, Valsalva maneuver, and edrophonium though non-pharmacological methods are used sometimes. They slow conduction by increasing the parasympathetic tone on the AV node.
Beta Blockers
Acute Beta Blocker Therapy
- Intravenous beta blocker like metoprolol, propranolol, and esmolol.
- Useful when atrial fibrillation is secondary to high adrenergic tone like in post operative situations.
Metoprolol
- Dose 2.5-5 mg over 2 minutes.
- Route - Intravenous.
- Maximum dose 15 mg.
- Doses can be repeated over 5 minutes interval.
Esmolol
- Short duration of action (10-20 min).
- Metabolized by RBC esterases.
- Advantage - It can be used in conditions where patient's response and tolerance to beta blocker is uncertain for e.g bradycardia. In these situations its short half-life permits a therapeutic trial to check the patient's response. Based on that the patient are started on other long acting beta blockers.
- Doses
- Infusion at rate of 50 µg/kg per min, with an increase in the rate of administration by 50 µg/kg per min every 30 minutes.
- Some hospitals prefer starting with a bolus of 0.5 mg/kg over one minute, followed by infusion of 50 µg/kg per min. Monitor for four minutes. In case of inadequate response, another bolus is given followed by an infusion of 100 µg/kg per min. Wait for 4 minutes. In case of inadequate response a third bolus can be given followed by an infusion at 150 µg/kg per min rate. The maximum infusion that can be given is 200 µg/kg per min.
Chronic Beta Blocker Therapy
- Oral beta blockers are preferred for treatment of chronic atrial fibrillation.
- Commonly used agents are: Atenolol, metoprolol, timolol, pindolol, nadolol and labetalol.
- Atenolol is the preferred over other agents due to its long half life, once daily dose, and less CNS side effects.
- Atenolol dose - 25 mg per day. Maximum dose permitted is 200 mg per day.
- Carvedilol has been found to be useful in patients with chronic heart failure due to systolic dysfunction.
Side Effects of Beta Blocker Therapy
Calcium Channel Blockers
2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation: Executive Summary (DO NOT EDIT)[2]
Rate Control: Recommendations
| Class I |
| "1. Control of the ventricular rate using a beta blocker or nondihydropyridine calcium channel antagonist is recommended for patients with paroxysmal, persistent, or permanent AF. (Level of Evidence: B) " |
| "2. Intravenous administration of a beta blocker or nondihydropyridine calcium channel blocker is recommended to slow the ventricular heart rate in the acute setting in patients without pre- excitation. In hemodynamically unstable patients, electrical cardioversion is indicated. (Level of Evidence: B) " |
| "3. In patients who experience AF-related symptoms during activity, the adequacy of heart rate control should be assessed during exertion, adjusting pharmacological treatment as necessary to keep the ventricular rate within the physiological range. (Level of Evidence: C) " |
| Class III: Harm |
| "1. AV nodal ablation with permanent ventricular pacing should not be performed to improve rate control without prior attempts to achieve rate control with medications. (Level of Evidence: C)" |
| "2. Nondihydropyridine calcium channel antagonists should not be used in patients with decompensated HF as these may lead to further hemodynamic compromise. (Level of Evidence: C)" |
| "3. In patients with pre-excitation and AF, digoxin, nondihydropyridine calcium channel antagonists, or intravenous amiodarone should not be administered as they may increase the ventricular response and may result in ventricular fibrillation. (Level of Evidence: B)" |
| "4. Dronedarone should not be used to control the ventricular rate in patients with permanent AF as it increases the risk of the combined endpoint of stroke, MI, systemic embolism, or cardiovascular death. (Level of Evidence: B)" |
| Class IIa |
| "1. A heart rate control (resting heart rate <80 bpm) strategy is reasonable for symptomatic management of AF. (Level of Evidence: B)" |
| "2. Intravenous amiodarone can be useful for rate control in critically ill patients without pre-excitation. (Level of Evidence: B)" |
| "3. AV nodal ablation with permanent ventricular pacing is reasonable to control the heart rate when pharmacological therapy is inadequate and rhythm control is not achievable. (Level of Evidence: B)" |
| Class IIb |
| "1. A lenient rate-control strategy (resting heart rate <110 bpm) may be reasonable as long as patients remain asymptomatic and LV systolic function is preserved. (Level of Evidence: B)" |
| "2. Oral amiodarone may be useful for ventricular rate control when other measures are unsuccessful or contraindicated. (Level of Evidence: C)" |
Sources
- 2011 ACCF/AHA/HRS Focused Updates Incorporated Into the ACC/AHA/ESC 2006 Guidelines for the Management of Patients With Atrial Fibrillation [3]
- 2011 ACCF/AHA/HRS Focused Update on the Management of Patients With Atrial Fibrillation (Updating the 2006 Guideline) [4]
References
- ↑ 1.0 1.1 Wyse DG, Waldo AL, DiMarco JP, Domanski MJ, Rosenberg Y, Schron EB, Kellen JC, Greene HL, Mickel MC, Dalquist JE, Corley SD (2002). "A comparison of rate control and rhythm control in patients with atrial fibrillation". N Engl J Med. 347 (23): 1825–33. PMID 12466506
- ↑ January, Craig T.; Wann, L. Samuel; Alpert, Joseph S.; Calkins, Hugh; Cleveland, Joseph C.; Cigarroa, Joaquin E.; Conti, Jamie B.; Ellinor, Patrick T.; Ezekowitz, Michael D.; Field, Michael E.; Murray, Katherine T.; Sacco, Ralph L.; Stevenson, William G.; Tchou, Patrick J.; Tracy, Cynthia M.; Yancy, Clyde W. (2014). "2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation: Executive Summary". Journal of the American College of Cardiology. doi:10.1016/j.jacc.2014.03.021. ISSN 0735-1097.
- ↑ Fuster V, Rydén LE, Cannom DS, Crijns HJ, Curtis AB, Ellenbogen KA et al. (2011) 2011 ACCF/AHA/HRS focused updates incorporated into the ACC/AHA/ESC 2006 guidelines for the management of patients with atrial fibrillation: a report of the American College of Cardiology Foundation/American Heart Association Task Force on practice guidelines. Circulation 123 (10):e269-367. DOI:10.1161/CIR.0b013e318214876d PMID: 21382897
- ↑ Wann LS, Curtis AB, January CT, Ellenbogen KA, Lowe JE, Estes NA; et al. (2011). "2011 ACCF/AHA/HRS focused update on the management of patients with atrial fibrillation (Updating the 2006 Guideline): a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines". Heart Rhythm. 8 (1): 157–76. doi:10.1016/j.hrthm.2010.11.047. PMID 21182985.