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Published on: July 29, 2011

The natural history of primary first-degree atrioventricular heart block

D Mymin, F A Mathewson, R B Tate

    The New England Journal of Medicine
    |November 6, 1986
    PubMed

    Insights

    First-degree heart block in healthy men without heart disease is generally benign. This condition, characterized by moderate PR interval prolongation, rarely progresses and shows no significant difference in mortality.

    Area of Science:

    • Cardiology
    • Preventive Medicine
    • Epidemiology

    Background:

    • The long-term prognosis of first-degree heart block (FHHB) in individuals without underlying organic heart disease remains unclear.
    • Previous studies have not definitively established the clinical significance and outcomes associated with FHHB.

    Purpose of the Study:

    • To investigate the long-term prognosis of primary first-degree heart block in healthy men.
    • To determine the incidence, progression, and associated mortality of FHHB over a 30-year period.

    Main Methods:

    • A 30-year longitudinal study involving 3983 healthy men.
    • Identification of 52 prevalent and 124 incident cases of FHHB.
    • Age-matched case-control analysis comparing FHHB cases with controls on various risk factors and health outcomes.

    Main Results:

    • The incidence of FHHB increased after age 40, with an overall rate of 1.13 per 1000 person-years.
    • Two-thirds of cases exhibited moderate PR interval prolongation (0.22-0.23 seconds).
    • No significant differences in mortality, smoking, blood pressure, or body-mass index were found between cases and controls. Rates of ischemic heart disease were not significantly different.

    Conclusions:

    • Primary first-degree heart block with moderate PR prolongation is a benign condition in healthy men.
    • Progression to higher grades of heart block is rare.
    • The prognosis may differ for individuals with more marked PR interval prolongation.

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