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Provocation testing in congenital long QT syndrome: A practical guide.
Timothy Abrahams1, Brianna Davies2, Zachary Laksman2
1Victorian Heart Institute & Monash Health Heart, Victorian Heart Hospital, Monash University, Melbourne, Victoria, Australia.
Heart Rhythm
|July 22, 2023
Summary
Congenital long QT syndrome (LQTS) diagnosis can be challenging as resting ECGs are often normal. Provocation testing, especially exercise stress tests, helps unmask LQTS by revealing abnormal heart repolarization responses.
Area of Science:
- Cardiology
- Genetics
- Electrophysiology
Background:
- Congenital long QT syndrome (LQTS) is a hereditary cardiac channelopathy affecting 1 in 2500 individuals.
- Resting QT interval corrected for heart rate (QTc) may be normal in up to 70% of genotype-positive LQTS patients.
- Unmasking LQTS diagnosis and predicting genotype can be achieved through provocation testing.
Purpose of the Study:
- To review the utility, strengths, and limitations of four LQTS provocation tests.
- To provide practical guidance for performing LQTS provocation testing.
- To identify the most effective provocation method for diagnosing LQTS.
Main Methods:
- Review of four LQTS provocation tests: stand-up test, exercise stress test, epinephrine challenge, and mental stress test.
- Assessment of repolarization during and after exercise, heart rate changes, and autonomic tone.
- Evaluation of diagnostic sensitivity and specificity.
Main Results:
- Provocation testing is crucial for diagnosing LQTS when resting ECGs are inconclusive.
- Patients with LQTS exhibit maladaptive repolarization responses during provocation.
- Exercise testing demonstrates the highest diagnostic utility considering sensitivity and specificity.
Conclusions:
- Provocation testing is valuable for diagnosing congenital long QT syndrome.
- Exercise testing is the most effective provocation method for LQTS diagnosis.
- Practical guidance for performing provocation tests is provided.
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