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Prolonged His-Q interval in chronic bifascicular block. Relation to impending complete heart block

Z Vera, D T Mason, R D Fletcher

    Circulation
    |January 1, 1976
    PubMed

    Insights

    Prolonged His-Q intervals in bifascicular block patients strongly predict complete heart block (CHB). This finding highlights the His-Q interval

    Area of Science:

    • Cardiology
    • Electrophysiology
    • Cardiac Electrophysiology

    Background:

    • Bifascicular block can indicate trifascicular disease, but the link between prolonged His-Q interval and complete heart block (CHB) risk is not well-documented.
    • The His-Q interval in conducted sinus beats approximates maximal His-Q prolongation before trifascicular block onset in patients with bifascicular block and Mobitz II or intermittent CHB.

    Observation:

    • His bundle electrocardiography (HBE) was conducted on 50 patients with chronic bifascicular block and Mobitz II or transient CHB.
    • Mobitz II or episodic CHB was observed in all patients before, during, or after HBE.
    • A prolonged His-Q interval (>55 msec) was found in 49/50 patients, with 47 showing substantial lengthening (≥65 msec).

    Findings:

    • Nearly all patients with bifascicular block and intermittent complete trifascicular block demonstrated marked His-Q prolongation.
    • A considerably lengthened His-Q interval in bifascicular block is a common prerequisite for, and strong indicator of, impending complete heart block.

    Implications:

    • The His-Q interval is a valuable predictor of complete heart block development in patients with bifascicular block.
    • This study provides crucial documentation supporting the use of His-Q interval assessment in managing patients with bifascicular block.
    • Further research may refine risk stratification and treatment strategies based on His-Q interval measurements.

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