Evaluating pro-arrhythmogenic effects of the T634S-hERG mutation: insights from a simulation study

Area of Science:

• Cardiovascular Physiology
• Molecular Cardiology
• Computational Biology

Background:

• The hERG K+ channel T634S mutation is a variant of uncertain significance with reported loss-of-function.
• Its impact on ventricular excitation and arrhythmogenesis remains uncharacterized.

Purpose of the Study:

• To evaluate the functional consequences of the T634S-hERG mutation on human ventricular excitation and arrhythmogenesis using multi-scale computer models.

Main Methods:

• Developed a Markov chain model for rapid delayed rectifier potassium current (I_Kr) for wild-type and T634S-hERG conditions.
• Integrated the I_Kr model into ten Tusscher et al. human ventricle models at cellular and tissue (1D, 2D, 3D) levels.
• Assessed effects on action potential duration (APD), APD rate-dependence (APDr), QT interval, vulnerability to conduction block (VW), spiral wave dynamics, and repolarization dispersion.

Main Results:

• The T634S-hERG mutation prolonged cellular APDs and steepened APDr.
• Simulations showed a prolonged QT interval, increased VW, destabilized re-entry, and augmented repolarization dispersion.
• These effects indicate a potential pro-arrhythmic impact.

Conclusions:

• The T634S-hERG mutation demonstrates significant pro-arrhythmic potential in human ventricular models.
• Findings suggest T634S-hERG may contribute to arrhythmias, consistent with Long QT Syndrome type 2 (LQT2).
• Computational modeling provides crucial insights into the arrhythmogenic risk of genetic variants.