Natural history of the PR interval and risk of cardiac events and mortality: a nationwide study.
Summary
In a nationwide cohort linking over 9 million ECGs to outcomes, both short and long PR intervals, as well as temporal PR prolongation, were associated with higher risks of AF/flutter, HF, ventricular arrhythmias, syncope, AV block/device implantation, and all-cause mortality. Risk patterns were U- or J-shaped for several endpoints, and ΔPR conferred stepwise risk across events.
Key Findings
- Short (<120 ms) and prolonged (>200 ms) PR intervals were present in 2.9% and 7.4%, with prolongation increasing with age.
- U-shaped associations for AF/flutter, HF, and ventricular arrhythmias; stepwise risk for syncope at PR ≥170 ms; linear risk for AV block/device at PR >160 ms.
- Temporal PR changes (ΔPR) showed stepwise increases in hazard across all evaluated events and mortality.
Clinical Implications
Consider PR interval level and changes over time in ECG-based surveillance and risk assessment; heightened monitoring and evaluation for conduction disease when PR ≥160–170 ms or showing progressive prolongation.
Why It Matters
Provides population-scale evidence that both baseline PR interval and its trajectory are clinically meaningful risk markers across diverse cardiac outcomes, informing ECG-based risk stratification.
Limitations
- Observational design with potential residual confounding and measurement variability in routine ECGs
- Lack of ambulatory monitoring limits arrhythmia burden quantification and mechanistic inference
Future Directions
Incorporate PR level/trajectory into risk scores; prospective studies to test targeted monitoring/interventions in patients with abnormal PR dynamics.
Study Information
- Study Type
- Cohort
- Research Domain
- Prognosis
- Evidence Level
- II - Nationwide observational cohort with repeated ECG measures and adjusted cause-specific analyses.
- Study Design
- OTHER