Rate dependence of sotalol-induced prolongation of ventricular repolarization during exercise in humans.
Why the study?
Does sotalol prolong QT interval duration in a rate-dependent manner during exercise in normal volunteers?
Population
10 normal volunteers
Comparison
Sotalol at three dosages administered for 4 days… vs Control period with no drug administered
Design
RCT, randomized, crossover study
Follow-up
4 days per dosage period
Authors
Discussion
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Implication
QT prolongation by sotalol is greater at slower rates; confirms and extends animal class III findings to humans.
Key Points
- To examine the physiological rate dependence of sotalol on ventricular repolarization across rest and exercise conditions in humans.
- Randomized crossover trial in 10 healthy volunteers testing three sotalol regimens (160, 320, and 640 mg/24 hr given for 4 days each) compared to a drug-free control period.
- Electrocardiographic recordings captured 50 to 100 QT intervals across varied RR intervals during baseline rest and maximal exercise testing.
- Determined plasma sotalol concentrations, quantified beta-adrenoceptor blockade by percentage reduction in peak exercise heart rate, and calculated rate-corrected QT intervals (QTc).
- Sotalol significantly reduced peak exercise heart rate by 13.8 ± 7% at 320 mg/day and 25.4 ± 8% at 640 mg/day (both p < 0.01).
- QTc interval prolonged by 5.8 ± 3.7% at 320 mg/day and 11.8 ± 3% at 640 mg/day (both p < 0.01), with threshold prolongation occurring at a mean concentration of 680 ng/ml (95% CI: 0–11.2%).
- QT prolongation increased as heart rate decreased, reaching statistical significance at RR intervals ≥800 ms for all doses and disappearing during exercise-induced tachycardia.
Structured PICO
Does sotalol prolong QT interval duration in a rate-dependent manner during exercise in normal volunteers?
P
Population
10 normal volunteers
I
Intervention
Sotalol at three dosages (160 mg/24 hr, 320 mg/24 hr, and 640 mg/24 hr) administered for 4 days each
C
Comparator
Control period with no drug administered
O
Outcome
QT interval duration on the surface electrocardiogram at rest and during a maximal exercise testsurrogate
Sotalol-induced QT prolongation is rate-dependent, being more pronounced at slower heart rates and not apparent during exercise-induced tachycardia.
Cite This Study
Funck‐Brentano et al. (1991) studied this question.