eMedicine Specialties > Emergency Medicine > Cardiovascular

Heart Block, First Degree: Follow-up

Author: Michael D Levine, MD, Physician, Department of Medical Toxicology, Banner Good Samaritan Medical Center
Coauthor(s): David FM Brown, MD, Assistant Professor, Division of Emergency Medicine, Harvard Medical School; Vice Chair, Department of Emergency Medicine, Massachusetts General Hospital
Contributor Information and Disclosures

Updated: Nov 16, 2009

Follow-up

Further Inpatient Care

  • In general, hospitalization specifically for first-degree atrioventricular (AV) block is not indicated. However, admission may be indicated for associated conditions (eg, myocardial infarction). Patients with a marked first-degree AV block (PR >300 msec) can present with symptoms similar to the pacemaker syndrome.2 In these individuals, admission may be indicated.
  • Guidelines from the American College of Cardiology, the American Heart Association, and the Heart Rhythm Society (ACC/AHA/HRS) recommend that permanent pacemaker implantation is reasonable for first-degree heart block with symptoms similar to those of pacemaker syndrome or hemodynamic compromise (class IIa recommendation; level of evidence, B).8 Additional ACC/AHA/HRS recommendations include the following:
    • Patients with first-degree AV block, with or without symptoms, may be considered for permanent pacemaker implantation if the block occurs in the setting of neuromuscular diseases such as myotonic muscular dystrophy, Erb dystrophy (limb-girdle muscular dystrophy), or peroneal muscular atrophy, because these patients may experience unpredictable progression of AV conduction disease ( class IIb recommendation, level of evidence, B).
    • Permanent pacemaker implantation is not indicated for asymptomatic first-degree AV block (class III recommendation; level of evidence, B).
  • Significant electrolyte abnormalities should be corrected.

Further Outpatient Care

  • In the absence of a disease process that requires admission, patients with first-degree AV block may be safely discharged and receive follow-up on an outpatient basis.
  • Patients should get serial follow-up ECGs to evaluate for progression to a higher-grade AV block.
  • Patients with first-degree AV block and coexistent bundle-branch block should be closely observed.

Complications

  • Patients with first-degree block can occasionally progress to higher-grade AV blocks. Usually, such a progression is only to a Mobitz type I, second-degree heart block, but occasionally, higher-grade block can occur. The later scenario is particularly seen in patients with an acute MI, myocarditis, or acute drug overdoses.
  • Drugs that slow conduction through the AV nodal system increase the risk of progression to higher-grade heart blocks. Administering such agents to a person with a coexisting first-degree AV block should be done with caution.

Prognosis

  • The prognosis for isolated first-degree atrioventricular (AV) block is very good. Progression from isolated first-degree heart block to high-degree block is very uncommon.9
  • Heart block in children with Lyme carditis tends to resolve spontaneously, with median recovery in 3 days (range: 1-7 days).5
  • Cheng et al found that first-degree heart block is associated with increased long-term risks of atrial fibrillation, pacemaker implantation, and all-cause mortality.10 Their community-based cohort included 7575 individuals from the Framingham Heart Study who had baseline routine 12-lead electrocardiography in 1968-1974 and underwent prospective follow-up through 2007.
    • Compared with individuals whose PR intervals were 200 msec or shorter, those with first-degree atrioventricular block had a 2-fold adjusted risk of atrial fibrillation (hazard ratio [HR], 2.06; 95% confidence interval [CI], 1.36-3.12; P<.001), a 3-fold adjusted risk of pacemaker implantation (HR, 2.89; 95% CI, 1.83-4.57; P<.001), and a 1.4-fold adjusted risk of all-cause mortality (HR, 1.44; 95% CI, 1.09-1.91; P=.01).
    • Each 20-msec increment in PR interval was associated with an adjusted HR of 1.11 (95% CI, 1.02-1.22; P = .02) for atrial fibrillation, 1.22 (95% CI, 1.14-1.30; P<.001) for pacemaker implantation, and 1.08 (95% CI, 1.02-1.13; P=.005) for all-cause mortality.
 


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References
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References

  1. John AD, Fleisher LA. Electrocardiography: the ECG. Anesthesiol Clin. Dec 2006;24(4):697-715, v-vi. [Medline].

  2. Barold SS, Ilercil A, Leonelli F, Herweg B. First-degree atrioventricular block. Clinical manifestations, indications for pacing, pacemaker management & consequences during cardiac resynchronization. J Interv Card Electrophysiol. Nov 2006;17(2):139-52. [Medline].

  3. Sherron P, Torres-Arraut E, Tamer D, Garcia OL, Wolff GS. Site of conduction delay and electrophysiologic significance of first-degree atrioventricular block in children with heart disease. Am J Cardiol. May 1 1985;55(11):1323-7. [Medline].

  4. Upshaw CB Jr. Comparison of the prevalence of first-degree atrioventricular block in African-American and in Caucasian patients: an electrocardiographic study III. J Natl Med Assoc. Jun 2004;96(6):756-60. [Medline].

  5. Costello JM, Alexander ME, Greco KM, Perez-Atayde AR, Laussen PC. Lyme carditis in children: presentation, predictive factors, and clinical course. Pediatrics. May 2009;123(5):e835-41. [Medline].

  6. Makaryus JN, Catanzaro JN, Goldberg S, Makaryus AN. Rapid progression of atrioventricular nodal blockade in a patient with systemic lupus erythematosus. Am J Emerg Med. Oct 2008;26(8):967.e5-7. [Medline].

  7. Berdajs D, Schurr UP, Wagner A, Seifert B, Turina MI, Genoni M. Incidence and pathophysiology of atrioventricular block following mitral valve replacement and ring annuloplasty. Eur J Cardiothorac Surg. Jul 2008;34(1):55-61. [Medline].

  8. [Guideline] Epstein AE, DiMarco JP, Ellenbogen KA, Estes NA 3rd, Freedman RA, Gettes LS, et al. ACC/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the ACC/AHA/NASPE 2002 Guideline Update for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices) developed in collaboration with the American Association for Thoracic Surgery and Society of Thoracic Surgeons. J Am Coll Cardiol. May 27 2008;51(21):e1-62. [Medline].

  9. Mymin D, Mathewson FA, Tate RB, Manfreda J. The natural history of primary first-degree atrioventricular heart block. N Engl J Med. Nov 6 1986;315(19):1183-7. [Medline].

  10. Cheng S, Keyes MJ, Larson MG, McCabe EL, Newton-Cheh C, Levy D, et al. Long-term outcomes in individuals with prolonged PR interval or first-degree atrioventricular block. JAMA. Jun 24 2009;301(24):2571-7. [Medline].

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Further Reading

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Keywords

heart block, first-degree heart block, first degree heart block, arrhythmia, cardiac arrhythmia, abnormal heart rhythm, atrioventricular block, first-degree atrioventricular block, AV block, first-degree AV block, prolongation of the PR interval, P wave, PR interval

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Contributor Information and Disclosures

Author

Michael D Levine, MD, Physician, Department of Medical Toxicology, Banner Good Samaritan Medical Center
Michael D Levine, MD is a member of the following medical societies: Alpha Omega Alpha, American College of Emergency Physicians, American College of Medical Toxicology, American Medical Association, Emergency Medicine Residents Association, Phi Beta Kappa, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Coauthor(s)

David FM Brown, MD, Assistant Professor, Division of Emergency Medicine, Harvard Medical School; Vice Chair, Department of Emergency Medicine, Massachusetts General Hospital
David FM Brown, MD is a member of the following medical societies: American College of Emergency Physicians and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Medical Editor

Theodore J Gaeta, DO, MPH, FACEP, Clinical Associate Professor, Department of Emergency Medicine, Joan and Sanford Weill Medical College at Cornell University; Vice Chairman and Program Director of Emergency Medicine Residency Program, Department of Emergency Medicine, New York Methodist Hospital; Academic Chair, Adjunct Professor, Department of Emergency Medicine, St George's University School of Medicine
Theodore J Gaeta, DO, MPH, FACEP is a member of the following medical societies: Alliance for Clinical Education, American College of Emergency Physicians, Clerkship Directors in Emergency Medicine, Council of Emergency Medicine Residency Directors, New York Academy of Medicine, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment

Managing Editor

Eddy Lang, MDCM, CCFP (EM), CSPQ, Assistant Professor, Department of Family Medicine, McGill University; Consulting Staff, Department of Emergency Medicine, The Sir Mortimer B Davis-Jewish General Hospital
Eddy Lang, MDCM, CCFP (EM), CSPQ is a member of the following medical societies: American College of Emergency Physicians
Disclosure: Nothing to disclose.

CME Editor

John D Halamka, MD, MS, Associate Professor of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center; Chief Information Officer, CareGroup Healthcare System and Harvard Medical School; Attending Physician, Division of Emergency Medicine, Beth Israel Deaconess Medical Center
John D Halamka, MD, MS is a member of the following medical societies: American College of Emergency Physicians, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Chief Editor

David FM Brown, MD, Assistant Professor, Division of Emergency Medicine, Harvard Medical School; Vice Chair, Department of Emergency Medicine, Massachusetts General Hospital
David FM Brown, MD is a member of the following medical societies: American College of Emergency Physicians and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

 
 
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