There is emerging evidence that low QRS voltages <0.5mV in the limb leads may be associated
with left ventricular myocardial fibrosis and a predisposition to serious ventricular
arrhythmias and sudden cardiac death (SCD). Sudden death in young individuals is highlighted
most commonly when an athlete is affected. A proportion of decedents are diagnosed with
idiopathic myocardial fibrosis at autopsy. Recent studies have revealed myocardial fibrosis
in athletes with low QRS complexes, who have survived a sudden cardiac arrest. Low QRS
voltages do not feature in the electrical anomalies that warrant further investigation
according to the international recommendations for electrocardiographic (ECG) interpretation
in athletes, hence there is no information on the precise significance or outcome data in
athletes with small QRS voltages. The investigators postulate that further evaluation of
athletes with low QRS voltages using CMR and gene analysis will help determine the prevalence
and significance of these ECG changes potentially identifying young vulnerable individuals at
risk of SCD. There are currently 2 studies which have assessed small QRS complexes in
athletes. These studies revealed 1.1-4% of Italian athletes had small QRS complexes. One
study performed ultrasound of the heart showing that athletes in general had larger hearts
compared to sedentary counterparts but no evidence of structural disease. The second study
did not perform CMR in all athletes with small QRS complexes and only conducted CMR in 5
athletes with small QRS complexes and electrical issues and demonstrated scar in 2 athletes.
The scientific basis of these studies does not prove the precise significance of small QRS
complexes on the ECG in this population to elucidate the sensitivity and specificity of
disease identification. It is possible that young individuals with serious cardiac
abnormalities may be identified if the significance of small QRS complexes is elucidated. The
prevalence of small QRS complexes in the general population is 0.3-2% but there is paucity of
data on prevalence and significance on small QRS complexes in young non-athletic individuals
aged 17-35 years old. This study will allow the investigators to identify the prevalence and
significance of small QRS complexes in athletes and non-athletes aged 17-35 years old
potentially identifying young vulnerable individuals at risk of sudden cardiac death. These
results should enable informed clinical decisions (at national and international level)
following pre-participation screening evaluation and help ultimately to identify young
individuals and athletes who are genuinely deemed to be at risk of sudden cardiac death (SCD)
whilst providing appropriate reassurance to those with normal QRS voltages. This study will
also potentially aid the investigators in updating the current recommendations on ECG
interpretation in athletes which will influence future international ECG recommendations in
athletes.This would be a cross-sectional observational study involving 240 participants aged
17-35 years old. This will involve 4 groups; 60 athletes with low QRS voltage and 60 age and
sex matched control group of athletes with normal QRS voltage, 60 non-athletes with low QRS
voltage and 60 age and sex matched controls with normal QRS voltage.