FM OCTOBER 2018 ISSUE - digital edition

are typically triggered during sleep or rest and are more
likely to be fatal. Molecular testing is an important aspect of
identifying the type of long QT syndrome and can help in
confirming clinical diagnosis as well as in guiding treatment
strategy. LQT1 and LQT2 are caused due to mutations in the
potassium channel genes, KCNQ1and KCNH2, respectively,
while LQT3 is caused by mutations in a sodium channel gene,
SCN5A.
‘For accurate treatment modality, we recommended
our patient to undergo molecular testing,’ said Dr. Hisham
Ahamed, Associate Professor in Cardiology, Amrita Institute
of Medical Sciences and Research, Kochi. Her family agreed,
and her blood sample was sent to MedGenome Labs,
Bengaluru, for a cardiac channelopathy panel. This panel
can identify mutations in cardiac ion channels that may
result in any abnormal variation in QT interval. The genetic
panel results showed that the patient had a mutation in
KCNH2and was therefore diagnosed as having type 2 long
QT syndrome.
While type 1 patients show good response to using
medications such as beta-blockers, type 2 patients generally
do not respond as well to such treatment and are typically
advised for implantable devices such as
an implantable cardioverter defibrillator
(ICD), if they are considered high-risk. Until
the patient’s family could agree for such a
procedure, the patient was started on betablockers,
since a subset of type 2 patients
can benefit from such medication as well.
The beta-blocker therapy has been effective
thus far for this patient. Two years later, she
has experienced no further episodes and
her heart rhythm has returned to normal
on its own. ‘’Our patient has been fortunate
that the beta-blocker treatment has worked
for her, although we would like to see the
patient follow through on the recommended
ICD implant,” says Dr. Ahamed. ‘’The lesson
learnt from this case is that ECG should be
performed in young individuals with a history
of seizures to rule out cardiac concerns.”
DR SHIVANEE SHAH
OCTOBER 2018 / FUTURE MEDICINE / 55