Summary
American Heart Association highlighted that 24-hour SDNN below 50ms is associated with significantly higher all-cause mortality risk, establishing a clinical threshold for concerning HRV levels.
Methods
Review of long-term studies on HRV and health outcomes
Key Findings
- 24-hour SDNN < 50ms associated with higher mortality
- Low HRV predicts cardiovascular events independently of other risk factors
- Association holds across age groups
- Short-term RMSSD also predictive but less studied for mortality
Limitations
Most studies in populations with existing heart disease
What This Means for You
If your HRV is consistently very low (SDNN < 50ms over 24 hours or morning RMSSD consistently under 20ms), consider talking to a doctor. While consumer devices don't measure clinical-grade HRV, persistently low readings warrant attention.
Source
Read the original paper in American Heart Association ↗
Added to HRV Zone: 2025-01-07