13th March 2024

Diagnostics

Diagnosis of congenital LQTS involves the following:

• ECG to look at the corrected QT (QTc) and T wave morphology
• Ruling out secondary causes of QT prolongation
• 24 ambulatory ECG monitoring
• Exercise stress test for exercise-associated arrhythmias

If congenital LQTS is suspected, then the Schwartz score is calculated to look at the likelihood of a congenital LQTS diagnosis. This looks at ECG findings and factors, including the patient’s clinical history and family history. A score of 3.5 points and above is classed as high risk, and the likelihood of the patient having congenital LQTS is 80%. Intermediate risk is classed as 1.5 to 3 points, and these individuals require genetic testing to evaluate if this is congenital. If the patient scores 0-1 points, then they are classed as low risk, and genetic testing should not be performed.