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Multifocal Atrial Tachycardia

Neeraj Tandon, MB, BS, Chief, Cardiology Section, Associate Professor of Medicine, Medical Service, Overton Brooks Veterans Affairs Medical Center
Pratap Reddy, MD, Director, Electrophysiology Service, Professor, Department of Medicine, Section of Cardiology, Louisiana State University Health Sciences Center

Updated: May 11, 2009

Introduction

Background

Multifocal atrial tachycardia (MAT) is an arrhythmia with an irregular atrial rate greater than 100 beats per minute (bpm). Atrial activity is well organized, with at least 3 morphologically distinct P waves, irregular P-P intervals, and an isoelectric baseline between the P waves. Shine, Kastor and Yurchak first proposed this definition in 1968.1 Multifocal atrial tachycardia has previously been described by names such as chaotic atrial rhythm or tachycardia, chaotic atrial mechanism, and repetitive paroxysmal MAT.

Pathophysiology

The mechanism of the arrhythmia has not been well defined. Delayed afterdepolarizations leading to triggered automaticity are postulated to result in the development of MAT. The evidence that implicates this mechanism is mainly indirect and points to intracellular calcium overload by various mechanisms (eg, catecholamine excess, phosphodiesterase inhibition, acidosis, hypoxemia). Electrolyte imbalances associated with severe underlying illnesses can further potentiate the development of this arrhythmia.

Frequency

United States

MAT is a relatively infrequent arrhythmia, with a prevalence rate of 0.05-0.32% in patients who are hospitalized. The condition is even less common in children and young adults.

Mortality/Morbidity

Patients with MAT frequently have significant comorbidities, especially chronic obstructive pulmonary disease (COPD) and respiratory failure, and are often treated in ICUs. Consequently, a high mortality rate (ie, up to 45%) is associated with this arrhythmia, although it is not a direct consequence of the rhythm abnormality.

Sex

MAT is predominantly observed in males.

Age

MAT is commonly observed in older patients. The average age of patients from 9 studies was 72 years.

Clinical

History

The clinical profile of patients who develop this arrhythmia includes pulmonary, cardiac, metabolic, and endocrinopathic disorders.

  • COPD is the most common underlying disease process (60%). The arrhythmia is commonly precipitated by exacerbation of COPD, sometimes due to infection or cardiac decompensation. Increasing hypoxemia with respiratory acidosis and advanced disease also leads to increased bronchodilator usage, thereby increasing catecholamine levels, which may contribute to development of MAT.
  • Cardiac: Patients with MAT frequently have cardiac diseases, mainly coronary artery disease and valvular heart diseases, often in conjunction with COPD. Congestive heart failure (CHF) is often present when the diagnosis of MAT is first made.
  • Metabolic disorders: In various series, 24% of patients with MAT were found to have diabetes mellitus. Fourteen percent had hypokalemia, and 14% had azotemia.
  • Postoperative: Twenty-eight percent of patients with MAT were recovering from major surgery, while others had postoperative infections, sepsis, pulmonary embolism, and CHF.
  • Pulmonary embolism: The link between pulmonary embolism and MAT is weak (ie, 6-14% of such patients have been said to have MAT), but the methods of diagnosing pulmonary embolism have not been well documented.
  • Intravenous drug abuse: Experimental evidence demonstrates that IV cocaine use may lead to the development of MAT.

Physical

Physical examination of the patient is typically related to findings associated with the underlying disease process and is not specific for MAT. The pulse is rapid and irregular2 , and the first heart sound may be variable. The physical examination is not typically sufficient to differentiate multifocal atrial tachycardia from atrial fibrillation.

Causes

Causes of MAT are mainly related to underlying illnesses.

  • The following common underlying illnesses are associated with this arrhythmia:
    • COPD
    • Coronary artery disease
    • CHF
    • Valvular heart disease
    • Diabetes mellitus
    • Hypokalemia
    • Hypomagnesemia
    • Azotemia
    • Postoperative state
    • Pulmonary embolism

Differential Diagnoses

Atrial Fibrillation
Atrial Flutter

Other Problems to Be Considered

Sinus tachycardia with frequent premature atrial contractions (PACs)

Workup

Laboratory Studies

  • Laboratory testing mainly consists of an assessment of serum chemistry level, blood hemoglobin level, and arterial blood gas levels.
    • Serum chemistry level - To exclude electrolyte disorders
    • Blood hemoglobin level and RBC counts - To seek evidence of anemia
    • Arterial blood gas level - To define pulmonary status
  • Further testing depends on the etiology of the underlying disease process.

Imaging Studies

  • Chest radiograph - To define pulmonary status
  • The diagnosis of multifocal atrial tachycardia (MAT) is confirmed with an ECG meeting the following criteria:
    • Irregular ventricular rate greater than 100 bpm
    • Organized and discrete P waves with at least 3 different morphologies in the same electrocardiographic lead
    • Irregular PP, PR, and RR intervals with an isoelectric baseline between the P waves
    • Some authors have suggested that patients who have rhythms with a rate less than 100 bpm but who satisfy all other criteria (including the clinical profile commonly observed with MAT) be considered to have cases of multifocal atrial rhythm and multifocal atrial bradycardia, when the rate is less than 60 bpm.
      • However, a controversy arises about whether this condition should be referred to as a MAT variant or a wandering atrial pacemaker. Patients with wandering atrial pacemaker usually do not have serious underlying illnesses.
      • The requirement that 3 different P waves should exist has been applied since early descriptions of the arrhythmia were recorded, but whether this should be interpreted as 2 ectopic P waves and 1 sinus P wave or 3 ectopic P waves has been a matter of controversy.
      • The consensus favors a minimum of 3 different waveforms in addition to sinus P waves.
  • Baseline noise on the ECG can mimic atrial fibrillation, and obscure differences in P wave morphology. Conversely, coarse atrial fibrillation on short recordings may appear to show discrete P waves prior to each QRS complex. Longer ECG recordings are therefore useful.

Treatment

Medical Care

  • General: Treatment of multifocal atrial tachycardia (MAT) involves treatment and/or reversal of the precipitating cause. This may be all that is required; however, the arrhythmia may recur when the underlying condition worsens. Treatment of underlying diseases may sometimes have arrhythmia-promoting effects; for example, theophylline and beta-agonist drugs used in patients with COPD produce an increased catecholamine state. These therapies should be used judiciously.
  • Calcium channel blockers: Diltiazem3 and verapamil4,5,6,7,8,9 decrease the atrial activity and slow atrioventricular (AV) nodal conduction, thereby decreasing ventricular rate, but they do not return all patients to normal sinus rhythm. Transient hypotension is the most common adverse effect, which may often be avoided by pretreating the patient with 1 g of intravenous calcium gluconate (10 mL of 10% calcium gluconate). Diltiazem may be used as a 20-45 mg intravenous bolus and then as a 10-25 mg/h continuous infusion. Verapamil may worsen hypoxemia by negating the hypoxic pulmonary vasoconstriction in underventilated alveoli; this is usually not clinically significant.
  • Beta-blockers: Metoprolol10,11,12,6,8 has been used to lower the ventricular rate. More patients convert to a normal sinus rhythm when treated with beta-blockers. Both oral and intravenous dosage forms have been used. The oral dosage is 25 mg q6h until the desired effects are obtained. Intravenous bolus dosing has been administered to as much as 15 mg over 10 minutes. Although no controlled studies have evaluated the use of short-acting beta-blockers in treatment of MAT, esmolol can also be used to control the ventricular rate as an intravenous infusion. It has a very short half-life and can be terminated quickly in the event of an adverse reaction. The use of beta-blockers is limited by transient hypotension and bronchospastic adverse effects since lung disease is commonly associated with MAT.
  • Magnesium: In a small number of patients, high-dose magnesium13,14,6,15,16 causes a significant decrease in the patient's heart rate and conversion to normal sinus rhythm. The dosage is 2 g intravenously over 1 minute, followed by 2 g/h infusion over 5 hours.
  • Antiarrhythmics: Oral and intravenous amiodarone17,18,19 (300 mg PO tid or 450-1500 mg IV over 2-24 h) has been used and has been reported to be associated with conversion to normal sinus rhythm. The success rate was 40% at 3 days with oral dosing and 75% on day 1 with intravenous dosing; however, this has been evaluated in a very small number of patients. Recent data support the use of amiodarone prophylactically postoperatively in patients with COPD. Case reports have also supported the use of ibutilide20 and flecainide21 for cardioversion.
  • Digitalis and cardioversion: Despite the urge to use digoxin, it has not been found to be effective in controlling the ventricular rate or restoring normal sinus rhythm. Digoxin promotes afterdepolarizations, which may promote the arrhythmia. Ventricular arrhythmias, AV block, and death have been reported when excessive digoxin has been administered to patients who were incorrectly diagnosed to have atrial fibrillation. Direct current (DC) cardioversion is not effective in conversion to normal sinus rhythm and can precipitate more dangerous arrhythmias.

Surgical Care

In patients who have persistent and recurrent episodes of MAT and problems with rate control, the AV node may be ablated using radiofrequency energy and a permanent pacemaker implanted.22

Medication

The goals of pharmacotherapy are to reduce morbidity and to prevent complications. Calcium channel blockers are used as the first line of treatment. Antiarrhythmics are usually not indicated for treatment of MAT. Consider using antiarrhythmics when the arrhythmia is symptomatic and does not respond to correction or treatment of underlying diseases.

Calcium channel blockers

Diltiazem and verapamil have been used to control the ventricular rate.


Diltiazem (Cardizem, Dilacor, Tiazac)

During depolarization, inhibits calcium ions from entering the slow channels and voltage-sensitive areas of vascular smooth muscle and myocardium.

Dosing

Adult

10-20 mg IV bolus, followed by 5-15 mg/h continuous infusion; alternatively, 120-360 mg PO divided tid/qid or qd in long-acting preparations

Pediatric

Not established

Interactions

May increase carbamazepine, digoxin, cyclosporine, and theophylline levels; when administered with amiodarone, may cause bradycardia and a decrease in cardiac output; when administered with beta-blockers, may increase cardiac depression; cimetidine may increase diltiazem levels

Contraindications

Documented hypersensitivity; severe CHF, sick sinus syndrome, second- or third-degree AV block, hypotension (<90 mm Hg systolic)

Precautions

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

Caution in impaired renal or hepatic function; may increase LFT levels, and hepatic injury may occur


Verapamil (Calan, Covera, Verelan)

During depolarization, it inhibits the calcium ion from entering slow channels or voltage-sensitive areas of the vascular smooth muscle and myocardium. By interrupting reentry at AV node, verapamil can occasionally restore normal sinus rhythm.

Dosing

Adult

0.075-0.15 mg/kg IV bolus over 5-10 min, followed by 0.005 mg/kg/min continuous infusion for 1 h; alternatively, 240-480 mg PO divided tid/qid

Pediatric

<2 years: Not established
>2 years: 0.075-0.15 mg/kg IV bolus over 2 min, followed by 0.005 mg/kg/min infusion

Interactions

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; may increase theophylline levels

Contraindications

Documented hypersensitivity; severe CHF, sick sinus syndrome, second- or third-degree AV block, hypotension (<90 mm Hg systolic)

Precautions

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

Antiarrhythmic agent

These agents promote the conversion of arrhythmia to normal sinus rhythm.


Magnesium sulfate

Used IV or IM, found to significantly slow the ventricular rate and to convert patients to normal sinus rhythm.

Dosing

Adult

2 g IV over 1 min followed by 2 g/h over 5 h continuous infusion; 1g IM q6h

Pediatric

25-50 mg/kg IV

Interactions

Concurrent use with nifedipine may cause hypotension and neuromuscular blockade; may increase neuromuscular blockade seen with aminoglycosides and potentiate neuromuscular blockade produced by tubocurarine, vecuronium, and succinylcholine; may increase CNS effects and toxicity of CNS depressants, betamethasone, and cardiotoxicity of ritodrine

Contraindications

Documented hypersensitivity; heart block; Addison disease; myocardial damage; severe hepatitis

Precautions

Pregnancy

A - Fetal risk not revealed in controlled studies in humans

Precautions

Magnesium may alter cardiac conduction, leading to heart block in patients who are digitalized; monitor respiratory rate, deep tendon reflex, and renal function when electrolytes are administered parenterally; caution when administering magnesium dose because it may produce significant hypertension or asystole; in overdose, a 10-20 mL IV of 10% calcium gluconate solution can be administered as an antidote for clinically significant hypermagnesemia

Follow-up

Further Inpatient Care

  • Further inpatient care is dictated by the underlying illness and treatment of this illness.
  • In patients with persistent and refractory multifocal atrial tachycardia (MAT), AV junctional ablation and permanent pacemaker implantation should be considered, both for symptomatic and hemodynamic improvement, and to prevent the development of tachycardia mediated cardiomyopathy.

Deterrence/Prevention

The best means of prevention of MAT is prevention of respiratory failure plus careful monitoring of all electrolyte disorders, namely, hypokalemia, hypomagnesemia, and drug therapy (mainly digoxin toxicity).

Complications

Potential complications include development of tachycardia-induced cardiomyopathy if the arrhythmia is persistent. Other complications include those due to drug therapy used to treat the arrhythmia.

Miscellaneous

Medicolegal Pitfalls

  • Clear differentiation of MAT from atrial fibrillation is very important because the treatment of atrial fibrillation differs from that of MAT.
  • MAT with aberration or preexisting bundle branch block may be misinterpreted as ventricular tachycardia.
  • Address underlying medical and metabolic issues.

Multimedia

ECG showing multifocal atrial tachycardia (MAT).

Media file 1: ECG showing multifocal atrial tachycardia (MAT).

References

  1. Shine KI, Kastor JA, Yurchak PM. Multifocal atrial tachycardia. Clinical and electrocardiographic features in 32 patients. N Engl J Med. Aug 15 1968;279(7):344-9. [Medline].

  2. Esperer HD, Esperer C, Cohen RJ. Cardiac arrhythmias imprint specific signatures on Lorenz plots. Ann Noninvasive Electrocardiol. Jan 2008;13(1):44-60. [Medline].

  3. Adcock JT, Heiselman DE, Hulisz DT. Continuous infusion diltiazem hydrochloride for treatment of multifocal atrial tachycardia (abstract). Clin Res. 1994;42:430A.

  4. Aronow WS, Plasencia G, Wong R. Effect of verapamil versus placebo on PAT and MAT. Current Ther Res. 1980;27:823-29.

  5. Hazard PB, Burnett CR. Verapamil in multifocal atrial tachycardia. Hemodynamic and respiratory changes. Chest. Jan 1987;91(1):68-70. [Medline].

  6. Kastor JA. Multifocal atrial tachycardia. N Engl J Med. Jun 14 1990;322(24):1713-7. [Medline].

  7. 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].

  8. Parillo JE. Treating Multifocal Atrial Tachycardia (MAT) in a critical care unit: new data regarding verapamil and metoprolol. Update Crit Care Med. 1987;2:3-5.

  9. Salerno DM, Anderson B, Sharkey PJ, Iber C. Intravenous verapamil for treatment of multifocal atrial tachycardia with and without calcium pretreatment. Ann Intern Med. Nov 1987;107(5):623-8. [Medline].

  10. Arsura E, Lefkin AS, Scher DL, et al. A randomized, double-blind, placebo-controlled study of verapamil and metoprolol in treatment of multifocal atrial tachycardia. Am J Med. Oct 1988;85(4):519-24. [Medline].

  11. Arsura EL, Solar M, Lefkin AS. Metoprolol in the treatment of multifocal atrial tachycardia. Crit Care Med. Jun 1987;15(6):591-4. [Medline].

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  13. Cohen L, Kitzes R, Shnaider H. Multifocal atrial tachycardia responsive to parenteral magnesium. Magnes Res. Dec 1988;1(3-4):239-42. [Medline].

  14. 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].

  15. McCord JK, Borzak S, Davis T, Gheorghiade M. Usefulness of intravenous magnesium for multifocal atrial tachycardia in patients with chronic obstructive pulmonary disease. Am J Cardiol. Jan 1 1998;81(1):91-3. [Medline].

  16. Ho KM. Intravenous magnesium for cardiac arrhythmias: jack of all trades. Magnes Res. Mar 2008;21(1):65-8. [Medline].

  17. Kouvaras G, Cokkinos DV, Halal G, et al. The effective treatment of multifocal atrial tachycardia with amiodarone. Jpn Heart J. May 1989;30(3):301-12. [Medline].

  18. Kuralay E, Cingoz F, Kilic S, et al. Supraventricular tachyarrythmia prophylaxis after coronary artery surgery in chronic obstructive pulmonary disease patients (early amiodarone prophylaxis trial). Eur J Cardiothorac Surg. Feb 2004;25(2):224-30. [Medline].

  19. Hsieh MY, Lee PC, Hwang B, Meng CC. Multifocal atrial tachycardia in 2 children. J Chin Med Assoc. Sep/2006;69:439-43. [Medline]. [Full Text].

  20. Pierce WJ, McGroary K. Multifocal atrial tachycardia and Ibutilide. Am J Geriatr Cardiol. Jul-Aug 2001;10(4):193-5. [Medline].

  21. Barranco F, Sanchez M, Rodriguez J, Guerrero M. Efficacy of flecainide in patients with supraventricular arrhythmias and respiratory insufficiency. Intensive Care Med. 1994;20(1):42-4. [Medline].

  22. Tucker KJ, Law J, Rodriques MJ. Treatment of refractory recurrent multifocal atrial tachycardia with atrioventricular junction ablation and permanent pacing. J Invasive Cardiol. Sep 1995;7(7):207-12. [Medline].

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  25. Cohen TJ. Skinning an old ailment (multifocal atrial tachycardia) with a new treatment (radiofrequency catheter ablation). J Invasive Cardiol. Sep 1995;7(7):213. [Medline].

  26. Habibzadeh MA. Multifocal atrial tachycardia: a 66 month follow-up of 50 patients. Heart Lung. Mar-Apr 1980;9(2):328-35. [Medline].

  27. Levine JH, Michael JR, Guarnieri T. Multifocal atrial tachycardia: a toxic effect of theophylline. Lancet. Jan 5 1985;1(8419):12-4. [Medline].

  28. Lipson MJ, Naimi S. Multifocal atrial tachycardia (chaotic atrial tachycardia). Clinical associations and significance. Circulation. Sep 1970;42(3):397-407. [Medline].

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Keywords

MAT, chaotic atrial rhythm, chaotic atrial tachycardia, chaotic atrial mechanism, repetitive paroxysmal multifocal atrial tachycardia, intracellular calcium overload, catecholamine excess, phosphodiesterase inhibition, acidosis, hypoxemia, electrolyte imbalances associated with severe underlying illnesses, COPD, congestive heart failure, metabolic disorders, diabetes mellitus, hypokalemia, azotemia, postoperative infections, sepsis, pulmonary embolism, respiratory acidosis, coronary artery disease, valvular heart disease, hypomagnesemia, azotemia, multifocal atrial rhythm, multifocal atrial bradycardia, wandering atrial pacemaker

Contributor Information and Disclosures

Author

Neeraj Tandon, MB, BS, Chief, Cardiology Section, Associate Professor of Medicine, Medical Service, Overton Brooks Veterans Affairs Medical Center
Neeraj Tandon, MB, BS is a member of the following medical societies: American College of Cardiology and Society of Cardiac Angiography and Interventions
Disclosure: Nothing to disclose.

Coauthor(s)

Pratap Reddy, MD, Director, Electrophysiology Service, Professor, Department of Medicine, Section of Cardiology, Louisiana State University Health Sciences Center
Pratap Reddy, MD is a member of the following medical societies: American College of Cardiology, American College of Physicians, American Federation for Medical Research, American Heart Association, and American Medical Association
Disclosure: Nothing to disclose.

Medical Editor

Alan D Forker, MD, Professor of Medicine, Program Director of Cardiovascular Fellowship, University of Missouri at Kansas City School of Medicine; Director, Outpatient Lipid Diabetes Research Center, MidAmerica Heart Institute of St Luke's Hospital
Alan D Forker, MD is a member of the following medical societies: Alpha Omega Alpha, American College of Cardiology, American College of Physicians, American Heart Association, American Medical Association, American Society of Hypertension, and Phi Beta Kappa
Disclosure: Research Grant Grant/research funds Hospital contracts to do research; I am a hospital employee with no personal profit; Speakers Bureau Honoraria Speaking and teaching

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Frank M Sheridan, MD, Cardiology, Providence Everett Medical Center
Frank M Sheridan, MD is a member of the following medical societies: American College of Cardiology, American Heart Association, and Society for Cardiac Angiography and Interventions
Disclosure: Nothing to disclose.

CME Editor

Amer Suleman, MD, Consultant in Electrophysiology and Cardiovascular Medicine, Department of Internal Medicine, Division of Cardiology, Medical City Dallas Hospital
Amer Suleman, MD is a member of the following medical societies: American College of Physicians, American Heart Association, American Institute of Stress, American Society of Hypertension, Federation of American Societies for Experimental Biology, Royal Society of Medicine, and Society of Cardiac Angiography and Interventions
Disclosure: Nothing to disclose.

Chief Editor

Jeffrey N Rottman, MD, Professor of Medicine and Pharmacology, Director, Clinical Cardiac Electrophysiology Fellowship Program, Vanderbilt University School of Medicine; Chief, Department of Cardiology, Nashville Veterans Affairs Medical Center
Jeffrey N Rottman, MD is a member of the following medical societies: American Heart Association and North American Society of Pacing and Electrophysiology (NASPE)
Disclosure: Nothing to disclose.

Further Reading

Clinical guidelines
Expert consensus document on beta-adrenergic receptor blockers.
European Society of Cardiology - Medical Specialty Society.  2004 Aug.  22 pages.  NGC:003854

Diagnosis and treatment of chest pain and acute coronary syndrome (ACS).
Institute for Clinical Systems Improvement - Private Nonprofit Organization.  2004 Nov (revised 2008 Oct).  69 pages.  NGC:006889

Practice standards for electrocardiographic monitoring in hospital settings: an American Heart Association scientific statement from the Councils on Cardiovascular Nursing, Clinical Cardiology, and Cardiovascular Disease in the Young.
American Heart Association - Professional Association.  2004 Oct 26.  26 pages.  NGC:003980

Clinical trials

Randomized Trial of Two Ablation Catheters in Paroxysmal Atrial Fibrillation

Pulmonary Vein (PV) -Isolation: Arrhythmogenic Vein(s) Versus All Veins

Routine Mini-Invasive Electrophysiology Study for Patients Feeling Tachycardia, With a Negative Holter ECG

Related eMedicine topics
Multifocal Atrial Tachycardia

Atrial Tachycardia

Paroxysmal Supraventricular Tachycardia

Atrial Fibrillation

Atrial Flutter

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