[SCD-FORUM] 146E Seven year old boy with suspected LQT3 Dr. Safer

[SCD Symposium]

Dear Dr. Costa,
 
definitely we can expect such a patient to be at high risk of a SCD (syncopes).
Though, as of the boy´s age I would have strict reservations to implant an ICD.
Maybe, it would be last ratio, if there where no else ways to avoid a SCD.
 
As for what you describe, the image of LQTS3 would fit, and the family history
confirms that there is a need for action:
 
(1) Would you be willing to share the boy´s ECGs here, so that we might have 
a better picture of what the alterations are? 
The QT-correction might be a little misleading, as with high heart rates, 
Bazett´s and also Fredericia´s correction will "overcorrect". 
Anyway, the ECG picture could help us to better understanding and discussion level.
 
(2) Did you take a Holter ECG of the patient?
To explore the nature of the syncope this is an ultimate need, as underlying ectopies
may happen during sleep phase, with nobody aware that they happened.
It would be reasonable to take Holters from the fater, mother and 2 sisters, too.
It is reasonable to look for any kind of complex ectopic events, and try 
to find T-wave alternans, and any kind of T-wave instability (like T-inversions).
That ought to bee good markers of SCD risk.
 
(3) Genotyping of the family should be performed, if ever possible.
Possibly colleagues here might be willing to help out with this task.
 
(4) As rate reduction by a beta-blocker did not help to shorten QTc,
the patient may be assessed for the reaction to QT-shortening drugs.
I would suggest to start infusion with low doses of Verapamile (or Lidocaine),
then titrate dose stepwise as long as reasonable and to assess the reaction by ECG.
Mobitz-2 blocks should be taken care of, and would be a sign to lower dose or stop.
Same is true if the QT/QTc would shorten too much.
If Verapamile would work, I would suggest to test an oral administration
(preferably with a sustained release formulation)until equivalent effect on QT/QTc
can be achieved compared to the infusion.
 
Best regards

Dr. Anton Safer
Weisenheim am Sand, Germany