Atrial fibrillation differential diagnosis

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Atrial fibrillation

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Atrial fibrillation must be distinguished from other common atrial arrhythmias, which include atrial flutter, atrial tachycardia, paroxysmal supraventricular tachycardia, Wolff-Parkinson-White syndrome, and atrioventricular nodal reentry tachycardia.

Differentiating Atrial Fibrillation from other Diseases

Atrial fibrillation has to be differnetiated from other diseases like:

• Atrial flutter
• Atrial tachycardia
• Atrioventricular nodal reentry tachycardia (AVNRT)
• Multifocal atrial tachycardia
• Paroxysmal supraventricular tachycardia
• Wolff-Parkinson-White syndrome

The differentiating features are largely based on both EKG findings and cardiovascular examination.

• Atrial fibrillation is irregularly irregular, while the other rhythms such as atrial flutter, sinus tachycardia, AV nodal reentry tachycardia and paroxysmal supraventricular tachycardia are all much more regular.
• An atrioventricular nodal reentry tachycardia will often break with either carotid sinus massage or AV nodal blocking agents.
• If the patient has Wolff-Parkinson-White syndrome there may be much more rapid conduction. The presence of the delta wave on EKG is characteristic.

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 SVTs	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 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 natruiretic 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 Pneumothroax Seizures Stroke
Ventricular Tacycardia	Regular	> 100 beats per minute		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.