What question did this study set out to answer?

To determine whether amiodarone, unlike d-sotalol, produces post-repolarization refractoriness to prevent premature excitation in ventricular tachycardia and to elucidate its biophysical mechanism.

October 31, 2014EP Europace

Drug-induced post-repolarization refractoriness as an antiarrhythmic principle and its underlying mechanism

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Why the study?

Does amiodarone compared to d-sotalol induce post-repolarization refractoriness and prevent inducible VT in patients with inducible ventricular tachycardia?

Key Points

To determine whether amiodarone, unlike d-sotalol, produces post-repolarization refractoriness to prevent premature excitation in ventricular tachycardia and to elucidate its biophysical mechanism.
Assessed 31 patients with inducible ventricular tachycardia randomized to treatment with either d-sotalol (n = 15) or amiodarone (n = 16) during programmed electrical stimulation.
Measured effective refractory periods across three extrastimuli and action potential duration at 90% repolarization using a Franz monophasic action potential catheter with simultaneous pacing capability.
Constructed a revised computer action potential model to simulate the underlying kinetics of cardiac sodium channel inactivation.
Both amiodarone and d-sotalol prolonged action potential duration, but amiodarone induced post-repolarization refractoriness in 12 of 16 patients (P < 0.001 vs. baseline), preventing ventricular tachycardia re-induction in all 12.
D-sotalol induced encroachment on repolarization without post-repolarization refractoriness across all patients, rendering ventricular tachycardia non-inducible in only 2 of 15 patients.
Computer simulations successfully replicated drug-induced post-repolarization refractoriness by altering the slow inactivation kinetics of the rapid sodium current.

Structured PICO

Does amiodarone compared to d-sotalol induce post-repolarization refractoriness and prevent inducible VT in patients with inducible ventricular tachycardia?

Population

31 patients with inducible ventricular tachycardia (VT) during programmed stimulation

Intervention

Amiodarone

Comparator

d-sotalol

Outcome

Effective refractory period (ERP), monophasic action potential duration at 90% repolarization (APD90), presence of post-repolarization refractoriness (PRR), and VT inducibilitysurrogate

Amiodarone, unlike d-sotalol, produces post-repolarization refractoriness which prevents premature excitation and effectively suppresses inducible ventricular tachycardia.

Discussion

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Implication

Amiodarone may be favored over d-sotalol to suppress inducible VT; confirms distinct mechanism and extends to clinical decision-making.

Cite This Study

Franz et al. (2014) studied this question.

synapsesocial.com/papers/6a71e20de36a167817e38b06 https://doi.org/10.1093/europace/euu274

Topics

Ventricular arrhythmias

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Drug-induced post-repolarization refractoriness as an antiarrhythmic principle and its underlying mechanism

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Topics

Drug-induced post-repolarization refractoriness as an antiarrhythmic principle and its underlying mechanism

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Also Consider

Topics

Also Consider