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Premature atrial contraction

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Cafer Zorkun, M.D., Ph.D. [2]; Mugilan Poongkunran M.B.B.S [3]

Synonyms and keywords: PAC, PACs, premature atrial contractions, premature atrial complex, premature atrial complexes, APC, APCs, atrial premature contraction, atrial premature contractions, atrial premature complex, atrial premature complexes, APB, atrial premature beat, atrial premature beats, extrasystole, premature atrial beat, premature atrial beats, premature supraventricular beat, premature supraventricular beat

Overview

Overview

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Mugilan Poongkunran M.B.B.S [2]

Overview

Premature atrial contractions (PACs) also known as atrial premature complex (APC), premature atrial beat or atrial premature beat (APB) is a benign type of premature heart beat which originates in one of the upper two chambers of the heart (the atria). PACs are to be distinguished from premature ventricular contractions (PVCs) that originate in one of the lower pumping chambers (the ventricles). PACs occur frequently in subjects with normal heart, however patients with structural heart disease and coronary heart disease are at increased risk.

Pathophysiology

Mechanisms responsible for spontaneous premature atrial contraction are not clear but reentry within the atrium is the most probable mechanism.

Causes

Premature atrial contraction occur frequently in subjects with normal heart, however patients with structural heart disease and coronary heart disease are at increased risk. Alcohol and coffee are considered potential precipitants of PACs. They may also be more common in other medical conditions such as chronic renal failure and chronic pulmonary disease.

Differentiating Premature Atrial Contraction from other Diseases

Premature atrial contraction need to be differentiated from other supraventricular premature beat that can originate from the atrioventricular node (AV node) or bundle of His. PACs also need to be distinguished from premature ventricular contractions (PVCs) that originate in one of the lower pumping chambers (the ventricles).

Epidemiology and Demographics

Premature atrial contraction (PAC) can occur at any age and they should not be always considered as an abnormal finding. The prevalence depends on the technique used for evaluation and the presence of heart disease.

Risk Factors

Smoking, alcohol, and coffee are considered potential precipitants of premature atrial contraction.

Natural History, Complications and Prognosis

Premature atrial contraction (PAC) is a common form of supraventricular arrhythmias and mostly the prognosis is good. In rare cases, severe symptoms other than palpitation may occur.

Diagnosis

History and Symptoms

Most patients with premature atrial contraction are asymptomatic. Rarely they present with palpitation and complications.

Physical Examination

Premature atrial contraction patients will demonstrate either premature pulse waves or pauses upon palpation of their peripheral pulse.

Laboratory Findings

Many cases of premature atrial contraction have no definite cause, it may be the result of various other problems. If PAC patients present with symptoms, a generalized approach is done to find the precipitating factors.

Electrocardiogram

Premature atrial contraction may have a variety of manifestations on the electrocardiogram. The diagnosis of an PACs is made when a P wave with a morphology different from that of the sinus P wave (inverted or biphasic) occurs earlier than the anticipated sinus P wave. It is always advisory to examine each lead as subtle differences in morphology may be present.

Treatment

Medical Therapy

No therapy is required for premature atrial contraction in asymptomatic individuals. If necessary, medical therapy should begin with a beta blocker.

References

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Historical Perspective

Historical Perspective

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References

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Classification

Classification

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Amandeep Singh M.D.[2]

Overview

There is no established system for the classification of Premature atrial contraction.

OR

Premature atrial contraction may be classified according to [classification method] into [number] subtypes/groups: [group1], [group2], [group3], and [group4].


Based on the duration of symptoms, Premature atrial contraction may be classified as either acute or chronic.


Classification

There is no established system for the classification of Premature atrial contraction.

OR

Premature atrial contraction may be classified according to [classification method] into [number] subtypes/groups:

  • [Group1]
  • [Group2]
  • [Group3]
  • [Group4]

OR

Based on the duration of symptoms, Premature atrial contraction may be classified as either acute or chronic.


References

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Pathophysiology

Pathophysiology

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Mugilan Poongkunran M.B.B.S [2]

Overview

Mechanisms responsible for spontaneous premature atrial contraction are not clear but reentry within the atrium is the most probable mechanism.

Pathophysiology

PACs occur frequently in subjects with normal hearts and hence it is difficult to establish a definite relationship to the factors that predispose to these extra beats. However the following could be the possible mechanisms for PACs :

References

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Causes

Causes

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Mugilan Poongkunran M.B.B.S [2]

Overview

Premature atrial contractions occur frequently in subjects with normal heart; however, patients with structural heart disease and coronary heart disease are at increased risk. Alcohol and coffee are considered potential precipitants of PACs. PAC’s may also be more common in other medical conditions such as chronic renal failure and chronic pulmonary disease.

Causes

Life Threatening Causes

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

Common Causes

Causes by Organ System

Cardiovascular Congenital heart disease, congestive heart failure, coronary heart disease, dilated cardiomyopathy, holiday heart syndrome, hypertensive heart disease, hypertrophic cardiomyopathy, mitral regurgitation, mitral stenosis, mitral valve prolapse, myocardial infarction, myocarditis, valvular heart disease, ischemic heart disease
Chemical / poisoning No underlying causes
Dermatologic No underlying causes
Drug Side Effect Alpha interferon, aminophylline, amiodarone, amlodipine, amphetamines, cocaine, digoxin, diltiazem, dobutamine, ephedrine, 5-fluorouracil, isoproterenol, phenylephrine, salbutamol, sympathomimetic agents, tacrolimus, theophylline, thiazides, verapamil
Ear Nose Throat No underlying causes
Endocrine Cushing’s syndrome, diabetic ketoacidosis, metabolic syndrome, subclinical hyperthyroidism, thyrotoxicosis
Environmental No underlying causes
Gastroenterologic No underlying causes
Genetic No underlying causes
Hematologic No underlying causes
Iatrogenic Acute cardiac allograft rejection, cardiac stress test, cardiac transplantation, cardioversion, pacemaker malfunction, transjugular intrahepatic portosystemic shunts
Infectious Disease Fever, myocarditis
Musculoskeletal / Ortho No underlying causes
Neurologic Subarachnoid hemorrhage
Nutritional / Metabolic Dehydration, electrolyte disturbance, hypokalemia, hypomagnesemia
Obstetric/Gynecologic New born
Oncologic No underlying causes
Opthalmologic No underlying causes
Overdose / Toxicity Amphetamines, cocaine, digoxin, cannabis
Psychiatric Anxiety disorders, bulimia nervosa, stress, Takotsubo cardiomyopathy
Pulmonary Chronic lung disease, COPD, hypoxia, pulmonary embolism, hypercapnia, respiratory acidosis, pneumonia, pulmonary hypertension, obstructive sleep apnea
Renal / Electrolyte Chronic renal failure
Rheum / Immune / Allergy Acute cardiac allograft rejection
Sexual No underlying causes
Trauma No underlying causes
Urologic No underlying causes
Dental No underlying causes
Miscellaneous Alcoholism, caffeine, chocolate, heavy exercise, fatigue, idiopathic

Causes in Alphabetical Order

References

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Differentiating Premature atrial contraction from other Diseases

Differentiating Premature atrial contraction from other Diseases

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];Associate Editor(s)-in-Chief: Syed Hassan A. Kazmi BSc, MD [2]Amandeep Singh M.D.[3]

Overview

Premature atrial contraction need to be differentiated from other supraventricular premature beat that can originate from the atrioventricular node (AV node) or bundle of His.

Differentiating Premature Atrial Contraction from other Diseases

Arrhythmia Rhythm Rate P wave PR Interval QRS Complex Response to Maneuvers Epidemiology Co-existing Conditions
Premature Atrial Contractrions (PAC)[1][2]
  • 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:
  • Usually narrow (< 0.12 s)
Atrial Fibrillation (AFib)[3][4]
  • Irregularly irregular
  • Absent
  • Fibrillatory waves
  • Absent
  • Less than 0.12 seconds, consistent, and normal in morphology in the absence of aberrant conduction
  • 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
Atrial Flutter[5]
  • 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
Atrioventricular nodal reentry tachycardia (AVNRT)[6][7][8][9]
  • Regular
  • 140-280 bpm
  • Slow-Fast AVNRT:
    • Pseudo-S wave in leads II, III, and AVF
    • Pseudo-R’ in lead V1.
  • Fast-Slow AVNRT
  • Slow-Slow AVNRT
  • 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
Multifocal Atrial Tachycardia[10][11]
  • 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
  • Less than 0.12 seconds, consistent, and normal in morphology
Paroxysmal Supraventricular Tachycardia
  • Regular
  • 150 and 240 bpm
  • Absent
  • Hidden in QRS
  • Absent
  • Narrow complexes (< 0.12 s)
Wolff-Parkinson-White Syndrome[12][13]
  • Regular
  • Atrial rate is nearly 300 bpm and ventricular rate is at 150 bpm
  • 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.
Ventricular Fibrillation (VF)[14][15][16]
  • Irregular
  • 150 to 500 bpm
  • Absent
  • Absent
  • Absent (R on T phenomenon in the setting of ischemia)
Ventricular Tachycardia[17][18]
  • 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
  • 5-10% of patients presenting with AMI


References

  1. ↑ Lin CY, Lin YJ, Chen YY, Chang SL, Lo LW, Chao TF, Chung FP, Hu YF, Chong E, Cheng HM, Tuan TC, Liao JN, Chiou CW, Huang JL, Chen SA (August 2015). “Prognostic Significance of Premature Atrial Complexes Burden in Prediction of Long-Term Outcome”. J Am Heart Assoc. 4 (9): e002192. doi:10.1161/JAHA.115.002192. PMC 4599506. PMID 26316525.
  2. ↑ Strasburger JF, Cheulkar B, Wichman HJ (December 2007). “Perinatal arrhythmias: diagnosis and management”. Clin Perinatol. 34 (4): 627–52, vii–viii. doi:10.1016/j.clp.2007.10.002. PMC 3310372. PMID 18063110.
  3. ↑ Lankveld TA, Zeemering S, Crijns HJ, Schotten U (July 2014). “The ECG as a tool to determine atrial fibrillation complexity”. Heart. 100 (14): 1077–84. doi:10.1136/heartjnl-2013-305149. PMID 24837984.
  4. ↑ Harris K, Edwards D, Mant J (2012). “How can we best detect atrial fibrillation?”. J R Coll Physicians Edinb. 42 Suppl 18: 5–22. doi:10.4997/JRCPE.2012.S02. PMID 22518390.
  5. ↑ Cosío FG (June 2017). “Atrial Flutter, Typical and Atypical: A Review”. Arrhythm Electrophysiol Rev. 6 (2): 55–62. doi:10.15420/aer.2017.5.2. PMC 5522718. PMID 28835836.
  6. ↑ Katritsis DG, Josephson ME (August 2016). “Classification, Electrophysiological Features and Therapy of Atrioventricular Nodal Reentrant Tachycardia”. Arrhythm Electrophysiol Rev. 5 (2): 130–5. doi:10.15420/AER.2016.18.2. PMC 5013176. PMID 27617092.
  7. ↑ Letsas KP, Weber R, Siklody CH, Mihas CC, Stockinger J, Blum T, Kalusche D, Arentz T (April 2010). “Electrocardiographic differentiation of common type atrioventricular nodal reentrant tachycardia from atrioventricular reciprocating tachycardia via a concealed accessory pathway”. Acta Cardiol. 65 (2): 171–6. doi:10.2143/AC.65.2.2047050. PMID 20458824.
  8. ↑ “Atrioventricular Nodal Reentry Tachycardia (AVNRT) – StatPearls – NCBI Bookshelf”.
  9. ↑ Schernthaner C, Danmayr F, Strohmer B (2014). “Coexistence of atrioventricular nodal reentrant tachycardia with other forms of arrhythmias”. Med Princ Pract. 23 (6): 543–50. doi:10.1159/000365418. PMC 5586929. PMID 25196716.
  10. ↑ Scher DL, Arsura EL (September 1989). “Multifocal atrial tachycardia: mechanisms, clinical correlates, and treatment”. Am. Heart J. 118 (3): 574–80. doi:10.1016/0002-8703(89)90275-5. PMID 2570520.
  11. ↑ Goodacre S, Irons R (March 2002). “ABC of clinical electrocardiography: Atrial arrhythmias”. BMJ. 324 (7337): 594–7. doi:10.1136/bmj.324.7337.594. PMC 1122515. PMID 11884328.
  12. ↑ Rao AL, Salerno JC, Asif IM, Drezner JA (July 2014). “Evaluation and management of wolff-Parkinson-white in athletes”. Sports Health. 6 (4): 326–32. doi:10.1177/1941738113509059. PMC 4065555. PMID 24982705.
  13. ↑ Rosner MH, Brady WJ, Kefer MP, Martin ML (November 1999). “Electrocardiography in the patient with the Wolff-Parkinson-White syndrome: diagnostic and initial therapeutic issues”. Am J Emerg Med. 17 (7): 705–14. doi:10.1016/s0735-6757(99)90167-5. PMID 10597097.
  14. ↑ Glinge C, Sattler S, Jabbari R, Tfelt-Hansen J (September 2016). “Epidemiology and genetics of ventricular fibrillation during acute myocardial infarction”. J Geriatr Cardiol. 13 (9): 789–797. doi:10.11909/j.issn.1671-5411.2016.09.006. PMC 5122505. PMID 27899944.
  15. ↑ Samie FH, Jalife J (May 2001). “Mechanisms underlying ventricular tachycardia and its transition to ventricular fibrillation in the structurally normal heart”. Cardiovasc. Res. 50 (2): 242–50. doi:10.1016/s0008-6363(00)00289-3. PMID 11334828.
  16. ↑ Adabag AS, Luepker RV, Roger VL, Gersh BJ (April 2010). “Sudden cardiac death: epidemiology and risk factors”. Nat Rev Cardiol. 7 (4): 216–25. doi:10.1038/nrcardio.2010.3. PMC 5014372. PMID 20142817.
  17. ↑ Koplan BA, Stevenson WG (March 2009). “Ventricular tachycardia and sudden cardiac death”. Mayo Clin. Proc. 84 (3): 289–97. doi:10.1016/S0025-6196(11)61149-X. PMC 2664600. PMID 19252119.
  18. ↑ Levis JT (2011). “ECG Diagnosis: Monomorphic Ventricular Tachycardia”. Perm J. 15 (1): 65. doi:10.7812/tpp/10-130. PMC 3048638. PMID 21505622.


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Epidemiology and Demographics

Epidemiology and Demographics

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Mugilan Poongkunran M.B.B.S [2]

Overview

Premature atrial contraction (PAC) can occur at any age and they should not be always considered as an abnormal finding. The prevalence depends on the technique used for evaluation and the presence of heart disease.

Epidemiology and Demographics

  • Premature atrial contraction occur commonly in both young and elderly subjects, however studies have shown that the frequency and prevalence of PACs appears to increase with age.[1]
  • The prevalence of PACs is highly dependent upon the technique used for evaluation. A 24-hour Holter monitoring is most preferred modality for the evaluation of premature ventricular complex.
  • The presence and frequency of PACs is dependent upon the presence of structural heart disease. They tend to occur more common in people with left ventricular dysfuction irrespective of the etiology.

References

  1. ↑ Romhilt DW, Chaffin C, Choi SC, Irby EC (1984). “Arrhythmias on ambulatory electrocardiographic monitoring in women without apparent heart disease”. Am J Cardiol. 54 (6): 582–6. PMID 6475777.

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Risk Factors

Risk Factors

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

Overview

Caffeine, smoking and alcohol are considered potential precipitants of premature atrial contraction.

Risk Factors

References

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Screening

Screening

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Amandeep Singh M.D.[2]

Overview

There is insufficient evidence to recommend routine screening for Premature atrial contraction.

Screening

There is insufficient evidence to recommend routine screening for Premature atrial contraction.

References

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Natural History, Complications and Prognosis

Natural History, Complications and Prognosis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Mugilan Poongkunran M.B.B.S [2]

Overview

Premature atrial contraction (PAC) is a common form of supraventricular arrhythmias and mostly the prognosis is good. In rare cases, severe symptoms other than palpitation may occur.

Natural History, Complications and Prognosis

References

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Diagnosis

Diagnosis

Diagnostic study of choice | History and Symptoms | Physical Examination | Laboratory Findings | Electrocardiogram | X-Ray Findings | Echocardiography | [[Premature atrial contraction CT scan|CT-Scan Findings] | MRI Findings | Cardiac Catheterization | Other Imaging Findings | Other Diagnostic Studies

Treatment

Treatment

Medical Therapy | Interventions | Surgery | Primary Prevention | Secondary Prevention | Cost-Effectiveness of Therapy | Future or Investigational Therapies

Case Studies

Case Studies

Case #1

Related Chapters


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