Long QT Syndrome
A guide to congenital and acquired long QT syndrome, arrhythmia risk, medicines, genetics and treatment.
Long QT syndrome is an electrical disorder that delays ventricular repolarisation and can predispose to torsades de pointes, fainting and sudden cardiac arrest. It may be inherited or acquired because of medicines, low potassium or magnesium, marked bradycardia or other illness.
Evaluation
The QT interval must be corrected for heart rate and interpreted in clinical context. Repeated ECGs, symptom history, family history, exercise or recovery testing and genetic evaluation may be used. A borderline value on one ECG neither proves nor excludes the diagnosis.
Risk Reduction and Treatment
Correcting electrolytes and avoiding relevant QT-prolonging medicines are fundamental. Beta blockers are central treatment for many patients with congenital long QT syndrome. An ICD is reserved for selected high-risk situations, such as survivors of cardiac arrest or recurrent events despite appropriate therapy. Family screening and genotype-specific counselling may be recommended.
Fainting during exertion, emotion or sudden auditory stimulation requires urgent specialist assessment.
Clinical Depth and Risk Assessment
Risk is not defined by the diagnostic label alone. Symptoms, ECG and rhythm findings, ventricular function, myocardial scar or structural change, family history, associated disease and previous events are integrated. Genetic results, when relevant, require expert interpretation; a variant of uncertain significance is not equivalent to a diagnosis.
Diagnostic Strategy and Limitations
Testing is selected to answer a specific question. ECG, ambulatory monitoring, echocardiography, cardiac MRI, CT, laboratory testing, exercise assessment or invasive evaluation have complementary roles. A normal test may not exclude an intermittent disorder, while an abnormal measurement must be checked against technical quality and clinical probability.
Treatment Decision Framework
Treatment may combine risk-factor control, condition-specific medicines, rhythm or heart-failure therapy, catheter procedures, surgery and implanted devices. These options address different mechanisms and are not automatically substitutes for one another. Expected benefit, uncertainty, procedural burden and the patient’s informed preferences should be discussed explicitly.
Long-Term Follow-up
Follow-up assesses symptoms, exercise capacity, rhythm burden, ventricular function and treatment tolerance over time. Family screening may be appropriate in inherited or suspected inherited disease. New fainting, sustained rapid rhythm, chest pain, neurological symptoms or rapidly worsening breathlessness requires urgent assessment.
Questions to Discuss With the Cardiology Team
- Which finding has the greatest influence on my present risk?
- Which test or treatment would genuinely change management?
- What symptoms should lead to an earlier appointment or emergency care?
- Do relatives need clinical or genetic assessment?
Medical Information Note
This page supports an informed discussion with the clinical team. It does not provide a personal diagnosis, medicine dose or sports-clearance decision.