Identification of Drug-Induced Multichannel Block and Proarrhythmic Risk in Humans Using Continuous T Vector Velocity...

Area of Science:

• Cardiology
• Pharmacology
• Biophysics

Background:

• Cardiac ventricular repolarization is crucial for heart rhythm.
• Assessing drug effects on repolarization is vital for predicting proarrhythmic risk.
• Current methods may not fully capture the dynamic nature of drug-induced repolarization changes.

Purpose of the Study:

• To introduce and validate continuous T vector velocity (TVV) effect profiles as a novel method for assessing drug effects on cardiac ventricular repolarization.
• To differentiate drug effects based on ion channel blockade and predict proarrhythmic potential.

Main Methods:

• TVV measures temporal changes in myocardial action potential distribution during repolarization.
• Heart rate-corrected T vector trajectory lengths (Tr(p)) were analyzed using functional mixed effects models.
• Bootstrap simulations approximated effect profile distributions, and a p_zero parameter identified repolarization transition points.

Main Results:

• TVV analysis revealed distinct signatures for potassium, sodium, and calcium channel blockade.
• Blockade of outward potassium currents caused continuous repolarization delay.
• Blockade of inward currents accelerated early repolarization, with the transition point (p_zero) predicting proarrhythmic risk.

Conclusions:

• Continuous TVV effect profiles provide a detailed assessment of drug actions across the entire ventricular repolarization interval.
• The p_zero parameter enhances proarrhythmic risk identification beyond QT prolongation.
• TVV analysis is a valuable tool for evaluating drug-induced repolarization changes and cardiac arrhythmia risk from clinical ECGs.