S/QRS ratio in lead I: A surface electrocardiographic finding associated with need for permanent pacemaker in patients with right bundle branch block.

Publication/Presentation Date

5-1-2026

Abstract

BACKGROUND: Right bundle branch block (RBBB) pattern does not imply normal left bundle branch conduction but may simply indicate a more diseased right bundle branch. In lead I, initial rapid QRS forces represent left ventricular depolarization and the terminal S wave represents slower right ventricular depolarization. We postulated that slurring of initial forces with resulting narrowing of the S-wave duration and a smaller S/QRS ratio may be associated with a need for a permanent pacemaker (PPM).

OBJECTIVE: This study aimed to assess the S/QRS ratio in lead I as an electrocardiogram measurement associated with a need for PPM.

METHODS: We measured the PR interval, QRS axis, QRS duration (QRS

RESULTS: A total of 218 patients with RBBB were included. For controls (n = 109), over a follow-up of 90.16 months (range 4.5-347), QRS

CONCLUSION: In patients with RBBB, narrowing of the S wave in lead I with an S/QRS ratio of < 0.56 is associated with increased need for PPM, even after adjusting for QRS

Volume

23

Issue

5

First Page

1204

Last Page

1211

ISSN

1556-3871

Disciplines

Business Administration, Management, and Operations | Health and Medical Administration | Management Sciences and Quantitative Methods

PubMedID

40398550

Department(s)

Administration and Leadership

Document Type

Article

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