View source for Answer 2008 06

{{NHJ|
|mainauthor= '''A.A.M. Wilde'''
|edition= 2008:06,221
}}
[[Image:Puzzle_2008_06_01.jpg|Figure 1|thumb]]

A36-year-old male comes to your outpatient clinic
because of his family history. His father died
suddenly at age 43 and his brother died suddenly at
age 39. Both had documented dilated cardiomyopathy.
He has no symptoms whatsoever. His ECG is
presented in figure 1. Ten years before the current
presentation he had an unremarkable cardiological
check-up (ECG, echo, X-ECG).

'''What is the most likely diagnosis, what would be your
next step and what would your eventual treatment
be?'''

==Answer 2008==

The ECG shows a supraventricular rhythm (60 beats/
min) where the P wave is only clearly visible in lead V1.
The PQ interval is markedly prolonged (400 msec),
QRS width is 110 msec with an intermediate electrical
axis. From the rhythm strip at the bottom of the figure
it is clear that the heart rate on the left side of the figure
is similar to that on the right side which argues in favour
of a regular supraventricular rhythm with very low
amplitude P waves in the extremity leads. In the middle
and on the far right the P wave is not followed by a QRS
complex. As judged from lead V1 there is no preceding
(further) PQ prolongation. Hence, a Mobitz II AV
block should be diagnosed.

This ECG (very low amplitude P waves, impaired
AV conduction and some intraventricular conduction
delay) in combination with a family history of dilated
cardiomyopathy is highly suggestive for a '''‘laminopathy’''',
i.e. a familial dilated cardiomyopathy based on a
mutation in the lamin A/C gene. A comparable ECG
(without second-degree AV block) can be seen in a previous [[The_ECG_of_a_(cardio)myopathy%3F|rhythm puzzle]]. A myopathy is frequently present
as well, but neuromuscular tests in this case revealed
no abnormalities. An echocardiogram revealed cardiac
dimensions at the upper limit of normal, which perfectly
fits with the diagnosis because frequently the conduction
disorders precede LV dysfunction. A mutation
in the lamin A/C gene could indeed be demonstrated.
The ECG without doubt necessitates pacemaker implantation.
Patients with laminopathies, however, seem
to be at particular high risk for sudden cardiac death,
even with a pacemaker implanted.<cite>Berlo</cite> ICD implantation
is therefore recommended when a pacemaker is considered.
Results from a recent small-scale prospective
study seem to underscore this policy,<cite>Meune</cite> but this study
may have been hampered by selection of particularly
‘malignant’ families. The present family history, however,
definitely warrants prophylactic ICD implantation
in this case.

==References==
<biblio>
#Berlo pmid=15551023
#Meune pmid=16407522
</biblio>