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.