Congenital Long QT Syndrome

Congenital Long QT Syndromes Sudeep Bansal Monday, March 2, 2009

• Most common genetic arrhythmia syndrome to cause sudden cardiac death • Abnormal QT prolongation in EKG • > 460 msec in women • > 440 msec in men • Death is by ventricular ﬁbrillation Monday, March 2, 2009

Cause • Multiple mutations identiﬁed (LQTS1, LQTS2…………. LQTS10) • Effect ion channels responsible to ventricular repolarization • 4% may have more than one mutation • Families generally have the same mutation Monday, March 2, 2009

• Most are autosomal dominant (Romano- Ward Syndrome) • Autosomal Recessive (Jervell Lange-Nielson syndrome - JLN) associated with congenital deafness Monday, March 2, 2009

LQTS1 • Most common (30-35%) • May be AD or AR (JLN syndrome) • Increased risk with emotional & physical stress • 99% cardiac events while swimming • Paradoxical ↑ in QTc with epinephrine infusion Monday, March 2, 2009

LQTS2 • Second most common (25-30%) • Syncope or SCD can occur with stress or at rest • Triggered by sudden loud noise (such as alarm clock) ~ 80% Monday, March 2, 2009

LQTS3 • Third most common • Syncope or SCD occur at rest or sleep (80%) Monday, March 2, 2009

Broad T-wave Low Amplitude Biﬁd T- wave Long isoelectric ST segment Monday, March 2, 2009

Approach to Diagnosis • Rule out secondary causes of Long QT • Detailed family history (including drowning, SIDS, car accidents) • Exercise testing - to determine effect of exercise in QT interval Monday, March 2, 2009

Genetic Testing • Test the proband ﬁrst • Negative test does not rule out mutation • Testing family - what if mutation is positive with normal QT interval? Monday, March 2, 2009

Risk Stratiﬁcation QTc 500 Higher Risk Risk 50% LQT1 & 2 Male LQT3 QTc < 500 QTc 500 Intermediate Risk Risk 30% - 50% Female LQT2 Female LQT3 Female LQT3 Male LQT3 QTc < 500 Low Risk Male LQT2 Risk <30% LQT1 Monday, March 2, 2009

Treatment • Avoid drugs that prolong QT • Beta-blockers (esp. For LQTS1) • Pacemaker • ICD • Use of anti-arrhythmics is uncertain Monday, March 2, 2009

From NEJM Jan 10, 2008 Monday, March 2, 2009

Thank You Monday, March 2, 2009

Congenital Long QT Syndrome

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