What question did this study set out to answer?

To assess whether isoproterenol infusion antagonizes the prolongation of right ventricular monophasic action potential duration induced by class III antiarrhythmic regimens in humans.

October 1, 1993Canadian Journal of Physiology and Pharmacology

Isoproterenol antagonizes drug-induced prolongation of action potential duration in humans

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Why the study?

Does isoproterenol antagonize drug-induced prolongation of action potential duration in patients with coronary disease?

Key Points

To assess whether isoproterenol infusion antagonizes the prolongation of right ventricular monophasic action potential duration induced by class III antiarrhythmic regimens in humans.
Measured right ventricular endocardial monophasic action potential duration at 90% repolarization and effective refractory period across cycle lengths of 300 to 600 ms.
Administered isoproterenol infusions in patients with coronary disease both without antiarrhythmic drugs and in the presence of class III regimens: amiodarone (N=3), sotalol plus quinidine (N=11), or sotalol alone (N=3).
Class III drugs increased action potential duration by an average of 9.2% at cycle lengths >300 ms (p < 0.05) and extended ventricular refractory period from 240 ± 5 to 269 ± 9.0 ms (p < 0.05).
Isoproterenol infusion in the presence of class III drugs significantly shortened the drug-prolonged action potential duration by an average of 8.1% across cycle lengths >300 ms (p < 0.05).
Without antiarrhythmic drugs, isoproterenol did not significantly alter action potential duration at any cycle length, but decreased the ventricular refractory period from 240 ± 5.0 to 225 ± 6.0 ms (p < 0.05).

Structured PICO

Does isoproterenol antagonize drug-induced prolongation of action potential duration in patients with coronary disease?

Population

Patients with underlying coronary disease but no evidence of inducible ischemia (N=17 in the drug group).

Intervention

Isoproterenol infusion in the presence of an antiarrhythmic drug regimen containing class III effects (amiodarone, sotalol plus quinidine, or sotalol alone).

Comparator

Isoproterenol infusion in the absence of antiarrhythmic drugs.

Outcome

Duration of the human right ventricular endocardial monophasic action potential at 90% repolarization.surrogate

Isoproterenol-induced sympathetic stimulation antagonizes the prolongation of action potential duration caused by class III antiarrhythmic drugs, suggesting that concomitant beta-blockade may augment the clinical utility of these agents.

Discussion

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Implication

Isoproterenol may blunt class III APD prolongation; leaves open whether beta-blockade augments utility in coronary disease.

Cite This Study

Newman et al. (1993) studied this question.

synapsesocial.com/papers/6a9a5259db3548d93776b680 https://doi.org/10.1139/y93-113

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Isoproterenol antagonizes drug-induced prolongation of action potential duration in humans

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Isoproterenol antagonizes drug-induced prolongation of action potential duration in humans

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Also Consider

Also Consider