Expertise is extremely important, in fact
expertise is the crux of our screening programme -
without expertise, one opens themselves up to
litigation.
The conditions that we’re dealing with are rare, one
considers that the prevalence of hypertrophic
cardiomyopathy is one in 500, the prevalence of ARVC is
one in 1000, the prevalence of Brugada syndrome is one
in 2000. So most general cardiologists will not have
seen many conditions such as hypertrophic cardiomyopathy.
It’s also important to be aware that these conditions
manifest in many, many different ways, they’re very
heterogeneous.
Let’s take hypertrophic cardiomyopathy for example.
Some individuals may develop very severe left
ventricular wall thickness - which is very easy to
recognise by everybody - but in others, there would be
no increase in left ventricular wall thickness, the only
manifestation of the condition will be an abnormality on
the ECG, and many cardiologists are not aware of this.
Similarly, arrhythmogenic right ventricular
cardiomyopathy may require numerous investigations
before it can be diagnosed. Long QT syndrome may fail
many cardiologists; they may fail to diagnose it because
of the various manifestations and the morphology of the
T-wave. So I believe expertise is extremely important.
It’s also important to be aware that people who
exercise a lot have to develop an increase in heart
size. That increase in heart size may reflect on the
ECG and in rare instances, may overlap with findings
seen in people with hypertrophic and arrhythmogenic
right ventricular cardiomyopathy. Fortunately, experts
in sports cardiology have the knowhow of differentiating
between physiology - that is, adaptation due to exercise
- from pathology; and that expertise is very limited
currently in the United Kingdom. The other important
issue is about the impact of exercise on the heart.
People who participate in a lot of sport will have
larger hearts than the general population and this
increase in heart size is sometimes reflected on the ECG.
There are some athletes who harbour ECG changes or
manifest ECG changes that overlap with those seen in
individuals with hypertrophic cardiomyopathy and
arrhythmogenic right ventricular cardiomyopathy. In
sports cardiology, there are various algorithms that
facilitate the differentiation of physiological changes
due to exercise, from pathological ones from
hypertrophic cardiomyopathy or arrhythmogenic right
ventricular cardiomyopathy. Most general cardiologists
are not familiar with these algorithms and could make
mistakes in this situation. It is also important to be
aware that in the context of long QT syndrome for
example, the resting ECG may just raise the suspicion of
the condition but further specialist tests may be
required to show up the syndrome. For this reason, I
think expertise is absolutely vital.
The other thing that one needs to consider is the
impact of age, gender, size and ethnicity on the ECG.
We know that childhood athletes have very different ECGs
compared to adult athletes. Black athletes have very
different ECGs compared to white athletes. Male
athletes have very different ECGs compared to female
athletes. Knowledge regarding cardiomyopathy,
physiological cardiac adaptation, determinance of ECGs,
the phenotypic manifestations of all of these conditions
that cause sudden cardiac death is absolutely vital if
we’re going to do this properly and reduce the risk of
false positives and false negatives which could have
very serious consequences.