CRY Research Fellow, Dr Abbas Zaidi, had the article ‘Physiological Right Ventricular Adaptation in Elite Athletes of African and Afro-Caribbean Origin’ published in the journal ‘Circulation’ (April 2013). [Full text here]
CRY Communications Officer, Mair Shepherd, caught up with him to find out more about this article.
- What was your research about?
We know that when people do regular exercise there are certain changes in the heart: the wall of the left ventricle gets thicker and the left ventricular cavity size gets bigger.
We’ve done quite a lot of research into the differences between black athletes and white athletes. We know that the left side of the heart actually remodels more in black athletes than it does in white athletes – black athletes get thicker left ventricular walls than white athletes.
The right side of the heart has been neglected historically – perhaps because it’s been perceived that it’s not as important as the left ventricle. Only really in the last few years has it become recognised that the right ventricle plays a very important part in the performance of athletes.
No-one has actually looked at what happens to the right ventricle of black athletes, so this project was looking at right ventricular adaptation in black athletes.
There have been some papers within the last few years looking at what happens to the right ventricle when people do exercise, and it has been found that the right ventricle also enlarges with regular exercise.
Now, the healthy athlete’s right ventricle can get bigger to the extent that it can start to look like a diseased ventricle; a condition called arrhythmogenic right ventricular cardiomyopathy (ARVC). That’s not to say that doing exercise will cause this condition but, if you exercise and the right ventricle gets bigger, it can cause confusion as to whether you are just seeing healthy enlargement of the heart or whether you’re seeing a disease.
So we thought we’d look at a cohort of black athletes to see what happens to their heart when they exercise.
- How did you collect the data?
Our data has come from screening with CRY. We’ve been collecting this data on black athletes since 2006. We looked at 375 white athletes and we compared their measurements with 300 black athletes. We also had a control group, so that’s non-athletic people – people who do less than 2 hours exercise per week – and that also had a mixture of black and white people.
We took an ECG and conducted echocardiograms for all of the subjects – and the echocardiogram is one of the key investigations because you can take measurements of the dimensions and the function of the right side of the heart. Those are the basic tests that everyone has when they come for screening through CRY, and they will also fill out a questionnaire where we ask them about symptoms and any family history of sudden death.
- What did the research show?
There are a few key messages from this paper. As we already know that the left ventricle gets thicker in black athletes than it does in white athletes, the first question we had was: are these changes mirrored in the right ventricle? Are there ethnic differences in the right ventricle? We actually found that, in black athletes, the right ventricle is slightly smaller than the white athletes’ right ventricle. However, the difference is so small that it’s almost insignificant, so we would recommend that you can use the same ‘normal’ values for the right ventricle when you’re looking at black athletes or white athletes.
Now the second thing we found was that, regardless of your colour – regardless of whether you’re black or white – if you do regular exercise then the right ventricle enlarges and in some cases it can enlarge quite significantly. So that’s another new message from this data.
One of the most important things that came out of this research was that black athletes are much more likely to have anterior T-wave inversions on the ECG. This has been shown already by several papers in our group – there was one from Dr Papadakis a few years ago. However, the condition that I talked about earlier – ARVC – is diagnosed by the finding of an enlarged right ventricle and anterior T-wave inversions on the ECG. The number of black athletes that had both a large right ventricle and T-wave inversion on the ECG was 10 times greater than the number of white athletes with a large right ventricle and T-wave inversion on the ECG. The meaning of this, is that you’re much more likely to misdiagnose in a black athlete with ARVC when in fact they don’t have that condition at all. It’s also known as a false positive. That’s probably the most important message to come out of this paper – you’re much more likely to get a wrong diagnosis in a black athlete when you’re assessing the right side of their heart.
- What is an anterior T-wave inversion?
One of the components of the ECG complex is called the T-wave, and generally speaking the T-wave should be upright. Now, sometimes we see inverted T-waves which means that the T-wave is upside down. This can be a normal physiological phenomenon – for example, as we are finding in black athletes – but it can also be seen in diseased states such as hypertrophic cardiomyopathy (HCM) and ARVC, and these are conditions that can cause sudden death in young people, particularly in athletes.
- What is the impact of false positives in diagnoses?
It will mean potentially months of anxiety and stress. It could mean that they are disqualified from sporting activities, temporarily or permanently. There is a big need for people to recognise that there is a greater scope for misdiagnosis or false positive diagnosis in black athletes.
- What are the wider implications of this research?
There was an editorial published in ‘Circulation’ at the same time that we published this paper. That editorial was written commenting on our paper, and one of the things that the editorial pointed out is that the current guidelines for diagnosing ARVC are perhaps going to have to be changed and our paper may well be contributing to changes in the guidelines. The guidelines at the moment would state that if you have an enlarged right ventricle and these T-wave inversions you may have ARVC, but the data here is suggesting that that’s not necessarily the case for black athletes.
It also emphasises the fact that screening needs to be done by people who have expertise in sports cardiology, who have expertise in what happens to the ECG of people who exercise regularly. If it is not done in an expert setting or by people with experience of these changes then we may well get a large number of false positives which can cause problems as we discussed before.