Early afterdepolarisation tendency as a simulated pro-arrhythmic risk indicator.

Area of Science:

• Cardiovascular toxicology
• Computational electrophysiology
• Pharmacology

Background:

• Drug-induced Torsades de Pointes (TdP) arrhythmia is a significant concern in predictive toxicology.
• While hERG channel blockade is implicated, it doesn't fully explain TdP occurrence, necessitating deeper mechanistic understanding.
• Early afterdepolarisations (EADs) are cellular events observed during TdP and represent a potential mechanistic link.

Purpose of the Study:

• To develop and evaluate a novel method for predicting TdP risk by simulating EADs induced by ion channel modulation.
• To assess the efficacy of EAD induction thresholds in classifying drug-induced TdP risk.
• To compare the predictive accuracy of EAD-based metrics against traditional hERG channel block and action potential duration simulations.

Main Methods:

• Utilized biophysically-based mathematical models of human ventricular cells.
• Induced EADs through interventions mimicking disease states: increased L-type calcium channel, decreased hERG channel, and shifted fast sodium channel inactivation.
• Classified drug risk based on the intervention threshold required to induce EADs.

Main Results:

• The L-type calcium channel-induced EAD metric demonstrated the highest accuracy in classifying drug risk categories.
• Combining L-type calcium EAD metrics with action potential duration measurements further improved predictive accuracy.
• EAD metrics generally outperformed hERG block alone but were less predictive than simulated action potential duration.

Conclusions:

• Simulating EADs offers a promising approach for predicting drug-induced TdP, potentially capturing diverse mechanistic pathways.
• Different EAD induction routes may reflect risk in distinct patient subgroups, highlighting the complexity of TdP prediction.
• Further research is needed to integrate these complex cellular mechanisms into robust clinical risk assessment tools.