Selective acquired long QT syndrome (saLQTS) upon risperidone treatment

Area of Science:

• Pharmacology
• Cardiology
• Genetics

Background:

• Antipsychotics can prolong the QT interval, leading to acquired long QT syndrome (aLQTS).
• This effect is often attributed to interactions with the KCNH2 potassium channel subunit.
• Individual responses to QT-prolonging drugs vary significantly, even in patients with aLQTS.

Observation:

• A case study details a patient experiencing aLQTS from low-dose risperidone, confirmed through multiple drug challenges.
• The same patient did not exhibit QT prolongation with other antipsychotics, including clozapine, which typically carries a higher risk.
• Genetic analysis revealed no mutations or polymorphisms in key cardiac ion channel genes (KCNH2, KCNE1, KCNE2, SCN5A, KCNQ1).

Findings:

• Patients can exhibit selective acquired long QT syndrome to a single antipsychotic.
• This selective response occurs without a detectable genetic basis in common ion channel genes.
• The findings challenge the notion of a universal KCNH2 channel target for all QT-prolonging antipsychotics.

Implications:

• Suggests the existence of an alternative, drug-selective target protein responsible for antipsychotic-induced aLQTS.
• Highlights the need for personalized risk assessment for QT prolongation in patients on antipsychotic medications.
• Opens new avenues for research into the specific mechanisms underlying selective drug-induced cardiac arrhythmias.