Arrhythmias & electrophysiology
S/QRS ratio in lead I: A surface electrocardiographic finding associated with need for permanent pacemaker in patients with right bundle branch block
Authors' 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 QRSd.
Study context
- Population
- Patients with right bundle branch block (RBBB), with or without a permanent pacemaker (PPM)patients with RBBB · controls 109 · cases 109
- Participants
- 218 patients
- Comparison
- S/QRS ratio in lead I as an electrocardiogram measurement associated with a need for PPM
- Controlsn = 109
- Casesn = 109
- Outcome
- QRS duration (QRSd)
- Follow-up
- 90.16 months (range 4.5-347) in controls; 89.22 months (range 2.21-262.75) in cases
Methodological detailsmultivariable analyses
- Multivariable analyses
Main finding
As reported in the abstract
| Group | Value | P |
|---|---|---|
| Controls | increase 145.2 to 146.7 ms | P = .67 |
| Cases | increase 139.9 to 147.6 ms | P < .001 |
Value
Controlsincrease 145.2 to 146.7 ms
Casesincrease 139.9 to 147.6 ms
P
ControlsP = .67
CasesP < .001
Further findings
Need for PPM
| Comparison | Odds ratio (CI) | P value | |
|---|---|---|---|
| S/QRS ratio of < 0.56Associated with a need for PPM · multivariable analyses | 6.87 (3.87–12.67) | P < 0.001 | |
| 0.050.21520Odds ratio (log scale) |
| Outcome | Controls | Cases |
|---|---|---|
| S/QRS ratio · follow-up of 90.16 months (range 4.5-347) in controls; 89.22 months (range 2.21-262.75) in cases | decrease 0.59 to 0.57 | decrease 0.52 to 0.43 |
| P | P = .02 | P < .001 |
Original publication
S/QRS ratio in lead I: A surface electrocardiographic finding associated with need for permanent pacemaker in patients with right bundle branch block. Heart Rhythm. Published 19 May 2025. doi:10.
Summarised from the published abstract; every number is checked against it