AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Background

Multifocal atrial tachycardia (MAT) is an irregular cardiac rhythm caused by at least 2 different sites of competing atrial activity.

Pathophysiology

MAT most often is found in the elderly patient with decompensated chronic lung disease and should be thought of as a hypoxic complication of underlying heart conduction pathology. However, other underlying causes may be present, such as congestive heart failure, sepsis, or methylxanthine toxicity. The effect of MAT on the heart conduction system may or may not lead to hemodynamic instability.

Frequency

United States

MAT is believed to be quite common. Usually, treatment of the patient's underlying problem (eg, respiratory failure, sepsis, theophylline toxicity) takes therapeutic precedent. The condition is transient and resolves when the underlying condition improves.

Mortality/Morbidity

• MAT is seldom life threatening. The overall clinical picture and symptoms improve when the underlying condition is addressed and MAT is controlled.
• Morbidity is difficult to quantify because the underlying disease is the primary determinant of complications.

Age

This is predominately a condition of the elderly patient with multiple medical problems.

CLINICAL

Section 3 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

History

• Patients may complain of a variety of symptoms, or more rarely patients may be asymptomatic. For those with complaints, the most common include the following:
• • Palpitations
  • Shortness of breath
  • Chest pain
  • Lightheadedness
  • Syncopal episode
  • Symptoms may be transient

Physical

• Pulse is rapid and irregular.
• Cardiac monitor and electrocardiogram show an irregular rapid tachycardia, usually narrow-complex.
• • It is often confused with atrial flutter or fibrillation.
  • It usually does not cause hemodynamic instability.
• Cardiac and pulmonary physical findings reflect the underlying process.
• Respiratory adventitial sounds often are prominent.
• Depending upon comorbid conditions or general health status, the patient may be hemodynamically unstable. However, determining if this is due to the underlying condition or the dysrhythmia may be difficult.

Causes

• Decompensated chronic lung disease due to any cause
• Congestive heart failure
• Sepsis
• Methylxanthine toxicity
• Myocardial infarction
• Pneumonia
• Pulmonary embolism
• Hypokalemia

DIFFERENTIALS

Section 4 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Other Problems to be Considered

Narrow-complex tachyarrhythmias
Sinus tachycardia
Wide-complex tachyarrhythmias

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Lab Studies

• Electrolytes
• Magnesium level
• Theophylline level (if patient is on, or has access to, this medication)
• Obtain other laboratory tests as clinically indicated (eg, CBC, cardiac markers, ABGs).

Imaging Studies

• Consider a portable anteroposterior (AP) chest radiograph to evaluate for pulmonary and cardiac findings particularly in the unstable patient.

Other Tests

• All patients are placed on pulse oximetry and a cardiac monitor.
• A 12-lead ECG with a rhythm strip is essential to make the diagnosis.
• • Multifocal atrial tachycardia (MAT) is suggested when 3 or more P wave morphologies are present.
  • Varying P-P, PR, and R-R intervals may indicate MAT.
  • The atrial rhythm of patients with MAT is 100-180 beats per minute.
  • A narrow QRS complex is present unless there is a conduction delay.

Procedures

Cardioversion is rarely successful in this population and should be avoided.

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Prehospital Care

• Assess for pulmonary causes that may be causing the arrhythmia.
• Stabilize the acute situation as necessary.
• Provide oxygen, cardiac monitoring, and pulse oximetry.
• Establish IV access without delaying transport.
• Collect medications that the patient may be taking or may have access to.

Emergency Department Care

• Rapidly assess and stabilize the ABCs while providing simultaneous treatment. An upright sitting position usually is most appropriate.
• Obtain IV access with a large-bore catheter with isotonic sodium chloride solution at a to keep open (TKO) rate.
• Administer oxygen to maintain the saturation greater than 90%, but avoid excessive oxygen in patients with known significant COPD. This will avoid the theoretical problem of removing the hypoxic drive for ventilation, which can result in increased carbon dioxide retention.
• The need for tracheal intubation is dictated by the standard clinical indications.
• Establish cardiac monitor, blood pressure monitor, and pulse oximetry.
• Assess for and treat the underlying cardiopulmonary process, theophylline toxicity, or metabolic abnormality. Bronchodilators and oxygen should be administered for treatment of decompensated chronic obstructive pulmonary disease (COPD); activated charcoal and/or charcoal hemoperfusion is the therapy for theophylline toxicity.
• When magnesium sulfate is administered to correct hypokalemia, most patients convert to normal sinus rhythm (NSR).
• Specific antiarrhythmic therapy is not commonly indicated and the value of such therapy is not proven. Metoprolol has been shown to be somewhat effective in converting MAT to NSR, and verapamil effectively slows the ventricular rate, but it is less effective in conversion to NSR.
• Due to the multiple atrial foci, cardioversion rarely is successful.
• Avoid sedatives.

Consultations

A cardiologist may be of assistance with ECG interpretation and may be available for consultation if antiarrhythmic therapy is being considered.

MEDICATION

Section 7 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Although specific drug therapy historically has not demonstrated great efficacy in treating MAT, several small reports describe effectiveness with the use of magnesium sulfate (with concomitant correction of hypokalemia), verapamil, and some beta-blockers.

Drug Category: Antiarrhythmics

In conjunction with the correction of the underlying medical process, these agents may provide conversion to NSR or control of the ventricular rate.

Drug Name	Verapamil (Calan, Covera-HS)
Description	During depolarization, inhibits calcium ion from entering slow channels or voltage-sensitive areas of vascular smooth muscle and myocardium.
Adult Dose	5-10 mg IV followed by a second dose 15-30 min later if the patient does not satisfactorily respond to the initial dose
Pediatric Dose	Not established
Contraindications	Documented hypersensitivity; severe CHF; sick sinus syndrome or second-degree or third-degree AV block; hypotension (<90 mm Hg systolic)
Interactions	Verapamil may increase carbamazepine, digoxin, and cyclosporine levels; coadministration with amiodarone can cause bradycardia and a decrease in cardiac output; when administered concurrently with beta-blockers may increase cardiac depression; cimetidine may increase verapamil levels; verapamil may increase theophylline levels
Pregnancy	C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions	Hepatocellular injury may occur; transient elevations of transaminases with and without concomitant elevations in alkaline phosphatase and bilirubin have occurred (elevations have been transient and may disappear with continued verapamil treatment); monitor liver function periodically

Drug Name	Metoprolol (Lopressor)
Description	Selective beta1-adrenergic receptor blocker that decreases the automaticity of contractions. During IV administration, carefully monitor blood pressure, heart rate, and ECG.
Adult Dose	Initially 5 mg IV q5min; not to exceed 15 mg
Pediatric Dose	Not established
Contraindications	Documented hypersensitivity; uncompensated congestive heart failure; bradycardia; asthma or severe COPD; cardiogenic shock; AV conduction abnormalities
Interactions	Aluminum salts, barbiturates, NSAIDs, penicillins, calcium salts, cholestyramine, and rifampin may decrease bioavailability and plasma levels of metoprolol, possibly resulting in decreased pharmacologic effects; toxicity of metoprolol may increase with coadministration of sparfloxacin, phenothiazines, astemizole, calcium channel blockers, quinidine, flecainide, and contraceptives; metoprolol may increase toxicity of digoxin, flecainide, clonidine, epinephrine, nifedipine, prazosin, verapamil, and lidocaine
Pregnancy	B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions	Beta-adrenergic blockade may reduce signs and symptoms of acute hypoglycemia and may decrease clinical signs of hyperthyroidism; abrupt withdrawal may exacerbate symptoms of hyperthyroidism, including thyroid storm; monitor patient closely and withdraw the drug slowly; during IV administration, carefully monitor blood pressure, heart rate, and ECG

FOLLOW-UP

Section 8 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Further Inpatient Care

• Most patients require admission to further manage their underlying cardiopulmonary diseases.
• These patients frequently are admitted to a monitored bed; however, the clinical scenario and the hemodynamic stability of the patient dictate disposition.

Further Outpatient Care

• Patients who convert to NSR after treatment and stabilization of the underlying process or by specific antiarrhythmic therapy may be cautiously considered for discharge.
• In order to be discharged, the patient must be back to baseline, have no complicating factors, be able to accomplish activities of daily living, and be available for close follow-up care.

Transfer

• For patients with theophylline toxicity, consider transfer to hospitals with hemoperfusion capabilities.

Deterrence/Prevention

• Close and careful management is required because of the underlying complex cardiopulmonary medical conditions.
• Surveillance and replacement as appropriate of electrolyte and magnesium levels
• Careful monitoring of theophylline levels in order to avoid toxicity

Complications

• Atrial thrombi with embolization and subsequent stroke
• Myocardial infarction from incongruous myocardial supply and demand
• Pulmonary emboli

Prognosis

• Depends on the prognosis of any comorbid disease

Patient Education

• Education about the causes of this arrhythmia may be beneficial.
• • In the case of a pulmonary source, education about prevention and recognition of developing pulmonary conditions may be helpful.
  • In the case of multifocal atrial tachycardia (MAT) related to medication use, education regarding the correct use and how to monitor such medications should be considered.

MISCELLANEOUS

Section 9 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical/Legal Pitfalls

• Treating MAT as atrial flutter or fibrillation
• Treating MAT with aberrancy as ventricular tachycardia
• Utilizing cardioversion or defibrillation when not indicated
• Failure to simultaneously correct hypokalemia when giving magnesium sulfate
• Failure to address the underlying medical problem; becoming distracted by the cardiac rhythm
• Discharging patients without adequately treating underlying medical problems

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

• Arsura EL, Solar M, Lefkin AS, et al. Metoprolol in the treatment of multifocal atrial tachycardia. Crit Care Med. Jun 1987;15(6):591-4. [Medline].
• Collier WW, Holt SE, Wellford LA. Narrow complex tachycardias. Emerg Med Clin North Am. Nov 1995;13(4):925-54. [Medline].
• Durham D, Worthley LI. Cardiac arrhythmias: diagnosis and management. The tachycardias. Crit Care Resusc. Mar 2002;4(1):35-53. [Medline].
• Hoffman JR, Votey SR. Tachyarrhythmias. In: Harwood-Nuss AL, Linden CH, Luten RC, et al, eds. The Clinical Practice of Emergency Medicine. 2^nd ed. Philadelphia, Pa: Lippincott-Raven; 1996:609.
• Iseri LT, Fairshter RD, Hardemann JL, Brodsky MA. Magnesium and potassium therapy in multifocal atrial tachycardia. Am Heart J. Oct 1985;110(4):789-94. [Medline].
• Kastor JA. Multifocal atrial tachycardia. Card Electrophysiol Rev. 2001;5:294-300.
• Levine JH, Michael JR, Guarnieri T. Treatment of multifocal atrial tachycardia with verapamil. N Engl J Med. Jan 3 1985;312(1):21-5. [Medline].
• Stapczynski JS. Disturbances of cardiac rhythm and conduction. In: Tintinalli JE, Ruiz E, Krome RL, eds. Emergency Medicine: A Comprehensive Study Guide. 4^th ed. New York, NY: McGraw-Hill; 1996:145.

Article Last Updated: Feb 4, 2008