March 1, 2000Pacing and Clinical Electrophysiology
Steady‐State versus Non‐Steady‐State QT‐RR Relationships in 24‐hour Holter Recordings
Key result
Automated beat-to-beat QT measurements on Holter recordings showed excellent agreement with manual ECGs, revealing that QT-RR intervals fit a linear relationship only under steady-state conditions.
Why the study?
What is the physiological QT-RR interval relationship in ambulatory ECG recordings under steady-state versus non-steady-state conditions?
Population
Healthy volunteers
Comparison
24-hour Holter recording with automated… vs Manual QT measurements on standard ECGs…
Design
Cohort
Follow-up
24 hours
Authors
Discussion
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Implication
Steady-state selection may improve QT assessment accuracy on Holter; leaves open effects on clinical risk stratification.
Key Points
- To investigate QT-RR interval relationships in ambulatory ECG recordings and determine the physiological conditions under which these intervals follow a linear relationship.
- Obtained 24-hour Holter recordings from healthy volunteers at baseline and after receiving the Class III antiarrhythmic drug dofetilide.
- Compared automated beat-to-beat Holter QT measurements directly to time-matched manual ECG measurements.
- Analyzed individual and group QT-RR relationships during 24-hour, daytime, and nighttime intervals under steady-state and non-steady-state cycle lengths using multiple correction formulas.
- Automated beat-to-beat Holter QT measurements showed excellent agreement with manual standard ECG readings following dofetilide administration.
- The traditional Bazett correction formula failed to fit QT-RR data points in both individual and group evaluations.
- Selecting beats with a stable rhythm over the preceding minute yielded linear QT-RR relationships during daytime and nighttime periods but not over 24 hours, whereas unselected beats followed a complex curvilinear relationship.
Study Design
Type
Observational
Structured PICO
What is the physiological QT-RR interval relationship in ambulatory ECG recordings under steady-state versus non-steady-state conditions?
P
Population
Healthy volunteers
I
Intervention
24-hour Holter recording with automated beat-to-beat QT measurements, at baseline and after dofetilide administration
C
Comparator
Manual QT measurements on standard ECGs; baseline vs post-dofetilide
O
Outcome
QT-RR interval relationship under steady-state vs non-steady-state conditionssurrogate
The QT-RR relationship in ambulatory ECGs is linear only under steady-state conditions during day and night, but curvilinear when beat selection is absent, highlighting the importance of steady rhythm selection for accurate QT assessment.
Cite This Study
Lande et al. (2000) conducted an observational in Healthy volunteers. Dofetilide vs. Baseline was evaluated on QT-RR interval relationship. Automated beat-to-beat QT measurements on Holter recordings showed excellent agreement with manual ECGs, revealing that QT-RR intervals fit a linear relationship only under steady-state conditions.