Multifocal atrial tachycardia

Multifocal atrial tachycardia

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-In-Chief: Sara Mohsin, M.D.[2] Cafer Zorkun, M.D., Ph.D. [3] Syed Hassan A. Kazmi BSc, MD [4]

Synonyms and keywords: MAT

Overview

Multifocal atrial tachycardia (MAT) or also called chaotic atrial tachycardia is a cardiac arrhythmia, specifically a type of supraventricular tachycardia (rate exceeding 100 beats per minute). This is characterized by 3 or more different P wave shapes  or contour, variable PP, PR and RR intervals. Most P waves are conducted to the ventricles but some are not. Some R  waves are aberrantly conducted.This variability makes it look irregular on the surface ECG and often misinterpreted as atrial fibrillation.

A rhythm with same the ECG characteristics but at a slow rate is called multifocal atrial rhythm (MAR).

It can be seen among elderly patients with COPD and CHF and eventually develop into atrial fibrillation. 

Historical Perspective

• Bradley et al reported the clinical course of MAT in infants and children in 2001.

Pathophysiology

• Possible mechanism for MAT has been suggested such as right atrial enlargement, hypercapnia, hypoxia, or adrenergic stimulation in pulmonary disease.3) The majority of MAT reports in pediatric patients have also reported not so low coexisting pulmonary disease (>20%) compared to the higher rate in adults (up to 60%). Unlike pulmonary physiology in adults, growth and development of bronchopulmonary system and pulmonary vessel continues for at least 2 years. It could be some role for the predominant infantile onset of MAT. Also, many of MAT have been detected in utero indicating that the immaturity and vulnerability of the atrium may also contribute to the infant-predominant age distribution of MAT.4) Therefore, immaturity of both the lungs and the heart might play a key role of infant-predominant age distribution and its favorable outcome in idiopathic infant cases.

Causes

Multifocal atrial tachycardia usually results from an underlying medical condition such as COPD, chronic renal failure, pulmonary embolism, electrolyte imbalance, and many other conditions.

Life Threatening Causes

Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated.

• Aminophylline toxicity
• Congestive heart failure
• Hypokalemia
• Hypoxia
• Myocardial infarction
• Pulmonary embolism
• Sepsis

Common Causes

• Chronic obstructive pulmonary disease
• Chronic renal failure
• Congestive heart failure
• Diabetes mellitus
• Hypokalemia
• Hypoxia
• Myocardial infarction
• Pneumonia
• Pulmonary embolism
• Sepsis

Causes by Organ System

Cardiovascular	Congestive heart failure, myocardial infarction, valvular heart disease
Chemical/Poisoning	No underlying causes
Dental	No underlying causes
Dermatologic	No underlying causes
Drug Side Effect	Aminophylline, isoproterenol, theophylline
Ear Nose Throat	No underlying causes
Endocrine	Diabetes mellitus
Environmental	No underlying causes
Gastroenterologic	No underlying causes
Genetic	No underlying causes
Hematologic	No underlying causes
Iatrogenic	Postoperative complication
Infectious Disease	Pneumonia, sepsis
Musculoskeletal/Orthopedic	No underlying causes
Neurologic	No underlying causes
Nutritional/Metabolic	No underlying causes
Obstetric/Gynecologic	No underlying causes
Oncologic	Lung cancer
Ophthalmologic	No underlying causes
Overdose/Toxicity	Aminophylline
Psychiatric	No underlying causes
Pulmonary	Chronic obstructive pulmonary disease, hypoxia, lung cancer, pneumonia, pulmonary embolism
Renal/Electrolyte	Chronic renal failure, hypokalemia, hypomagnesemia
Rheumatology/Immunology/Allergy	No underlying causes
Sexual	No underlying causes
Trauma	No underlying causes
Urologic	No underlying causes
Miscellaneous	No underlying causes

Causes in Alphabetical Order

• Aminophylline
• Chronic obstructive pulmonary disease
• Chronic renal failure
• Congestive heart failure
• Diabetes mellitus
• Hypercapnia
• Hypokalemia
• Hypomagnesemia
• Hypoxia
• Isoproterenol
• Lung cancer
• Myocardial infarction
• Pneumonia
• Postoperative complication
• Pulmonary embolism
• Sepsis
• Valvular heart disease

Epidemiology and Demographics

• Although the prevalence of pulmonary disease in MAT has been well established in adult MAT patients, particularly those with pulmonary diseases including chronic obstructive pulmonary disease, it is relatively rare in the pediatric ages. Therefore, the clinical feature of MAT in children is not well known with several studies of small cases.

Natural history, Complications, and Prognosis

• Baek et al reported the clinical outcome of MAT and potential prognostic factors. Compared to the previous reports, this study has relatively large number of patients and composed of various etiologies despite of limitation of retrospective study from single tertiary center. Among 33 patients with identified MAT, 27 (82%) were infantile onset and 10 patients (30%) had fetal diagnosis. Incidental detection without significant clinical manifestation is rather high (27%). Comorbidities had a variety of SHD (42%) and lung disease (24%). Interestingly, syndromic diagnosis, including 3 with Costello syndrome and 2 with Noonan syndrome, and one suggestive of RASopathy were noted in infantile onset group. Among 27 patients with infant onset of MAT, 11 patients (41%) were included in the idiopathic group. Accompanying arrhythmias was revealed in 4 patients (2 atrioventricular reentrant tachycardia prior to MAT diagnosis; 2 catecholaminergic polymorphic ventricular tachycardia [CPVT] after MAT diagnosis). The arrhythmia control rate was higher in the infant group (85%) than in the non-infant group (67%), although this trend was not statistically significant. There was a significantly lower rate of unfavorable outcomes in the idiopathic infant group (n=11) than in the other groups (p=0.008). Considering the findings of previous studies, the mortality rate was significantly higher in patients with SHD than in patients without (21% vs. 5%, p=0.01). The idiopathic infant group had a significantly lower rate of unfavorable outcomes than did the others (0% vs. 47%, p=0.008).

Diagnosis

Electrocardiography

• There are P waves of varying morphology from at least three different foci
• There is absence of one dominant atrial pacemaker
• Variable PP intervals, RR intervals, and PR intervals
• Atrial rate is above 100 beats per minute (bpm)
• Can be mistaken for atrial fibrillation if the p waves are of low amplitude
• High incidence in the elderly and in those with COPD

Treatment

• Combined flecainide and sotalol therapy for multifocal atrial tachycardia in cardio-facio-cutaneous syndrome.

Differentiating Multifocal Atrial Tachycardia From Other Disease

Arrhythmia	Rhythm	Rate	P wave	PR Interval	QRS Complex	Response to Maneuvers	Epidemiology	Co-existing Conditions
Atrial Fibrillation (AFib)	Irregularly irregular	On a 10-second 12-lead EKG strip, multiply number of QRS complexes by 6	Absent Fibrillatory waves	Absent	Less than 0.12 seconds, consistent, and normal in morphology in the absence of aberrant conduction	Does not break with adenosine or vagal maneuvers	2.7–6.1 million people in the United States have AFib 2% of people younger than age 65 have AFib, while about 9% of people aged 65 years or older have AFib	Elderly Following bypass surgery Mitral valve disease Hyperthyroidism Diabetes Heart failure Ischemic heart disease Chronic kidney disease Heavy alcohol use Left chamber enlargement
Atrial Flutter	Regular or Irregular	75 (4:1 block), 100 (3:1 block) and 150 (2:1 block) beats per minute (bpm), but 150 is more common	Sawtooth pattern of P waves at 250 to 350 bpm Biphasic deflection in V1	Varies depending upon the magnitude of the block, but is short	Less than 0.12 seconds, consistent, and normal in morphology	Conduction may vary in response to drugs and maneuvers dropping the rate from 150 to 100 or to 75 bpm	Incidence: 88 per 100,000 individuals	Elderly Alcohol
Atrioventricular nodal reentry tachycardia (AVNRT)	Regular	140-280 bpm	Slow-Fast AVNRT: Pseudo-S wave in leads II, III, and AVF Pseudo-R' in lead V1. Fast-Slow AVNRT P waves between the QRS and T waves (QRS-P-T complexes) Slow-Slow AVNRT Late P waves after a QRS Often appears as atrial tachycardia. Inverted, superimposed on or buried within the QRS complex (pseudo R prime in V1/pseudo S wave in inferior leads)	Absent (P wave can appear after the QRS complex and before the T wave, and in atypical AVNRT, the P wave can appear just before the QRS complex)	Less than 0.12 seconds, consistent, and normal in morphology in the absence of aberrant conduction QRS alternans may be present	May break with adenosine or vagal maneuvers	60%-70% of all supraventricular tachycardias	Structural heart disease Atrial tachyarrhythmias
Multifocal Atrial Tachycardia	Irregular	Atrial rate is > 100 beats per minute	Varying morphology from at least three different foci Absence of one dominant atrial pacemaker, can be mistaken for atrial fibrillation if the P waves are of low amplitude	Variable PR intervals, RR intervals, and PP intervals	Less than 0.12 seconds, consistent, and normal in morphology	Does not terminate with adenosine or vagal maneuvers	0.05% to 0.32% of electrocardiograms in general hospital admissions	Elderly Chronic obstructive pulmonary disease (COPD)
Paroxysmal Supraventricular Tachycardia	Regular	150 and 240 bpm	Absent Hidden in QRS	Absent	Narrow complexes (< 0.12 s)	Breaks with vagal maneuvers, adenosine, diving reflex, oculocardiac reflex	Prevalence: 0.023 per 100,000	Alcohol Caffeine Nicotine Psychological stress Wolff-Parkinson-White syndrome
Premature Atrial Contractrions (PAC)	Regular except when disturbed by premature beat(s)	80-120 bpm	Upright	> 0.12 second May be shorter than that in normal sinus rhythm (NSR) if the origin of PAC is located closer to the AV node Ashman’s Phenomenon: PAC displaying a right bundle branch block pattern	Usually narrow (< 0.12 s)	Breaks with vagal maneuvers, adenosine, diving reflex, oculocardiac reflex		Infants Cardiomyopathy Myocarditis Elderly Coronary artery disease Stroke Increased atrial natriuretic peptide (ANP) Hypercholesterolemia
Wolff-Parkinson-White Syndrome	Regular	Atrial rate is nearly 300 bpm and ventricular rate is at 150 bpm	With orthodromic conduction due to a bypass tract, the P wave generally follows the QRS complex, whereas in AVNRT, the P wave is generally buried in the QRS complex.	Less than 0.12 seconds	A delta wave and evidence of ventricular pre-excitation if there is conduction to the ventricle via ante-grade conduction down an accessory pathway A delta wave and pre-excitation may not be present because bypass tracts do not conduct ante-grade.	May break in response to procainamide, adenosine, vagal maneuvers	Worldwide prevalence of WPW syndrome is 100 - 300 per 100,000	Ebstein's anomaly Mitral valve prolapse: This cardiac disorder, if present, is associated with left-sided accessory pathways. Hypertrophic cardiomyopathy: This disorder is associated with familial/inherited form of WPW syndrome. Hypokalemic periodic paralysis Pompe disease Tuberous sclerosis
Ventricular Fibrillation (VF)	Irregular	150 to 500 bpm	Absent	Absent	Absent (R on T phenomenon in the setting of ischemia)	Does not break in response to procainamide, adenosine, vagal maneuvers	3-12% cases of acute myocardial infarction (AMI) Out of 356,500 out of hospital cardiac arrests, 23% have VF as initial rhythm	Myocardial ischemia / infarction Cardiomyopathy Channelopathies e.g. Long QT (acquired / congenital) Electrolyte abnormalities (hypokalemia/hyperkalemia, hypomagnesemia) Aortic stenosis Aortic dissection Myocarditis Cardiac tamponade Blunt trauma (Commotio Cordis) Sepsis Hypothermia Pneumothorax Seizures Stroke
Ventricular Tachycardia	Regular	> 100 bpm (150-200 bpm common)	Absent	Absent Initial R wave in V1, initial r > 40 ms in V1/V2, notched S in V1, initial R in aVR, lead II R wave peak time ≥50 ms, no RS in V1-V6, and atrioventricular dissociation	Wide complex, QRS duration > 120 milliseconds	Does not break in response to procainamide, adenosine, vagal maneuvers	5-10% of patients presenting with AMI	Coronary artery disease Aortic stenosis Cardiomyopathy Electrolyte imbalances (e.g., hypokalemia, hypomagnesemia) Inherited channelopathies (e.g., long-QT syndrome) Catecholaminergic polymorphic ventricular tachycardia Arrhythmogenic right ventricular dysplasia Myocardial infarction Torsades de pointes is a form of polymorphic VT that is often associated with a prolonged QT interval

Additional resources

• ECGpedia: Course for interpretation of ECG

Examples

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