The effect of Afro-Caribbean ethnicity on cardiac adaptation to exercise and the expression of hypertrophic cardiomyopathy : a clinical and genetic study

• Main Author: Sheikh, Nabeel
• Other Authors: Sharma, Sanjay
• Published: St George's, University of London 2017
• Subjects: 616.1
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.719262

Background and Aims: Athlete’s heart in adolescent African/Afro-Caribbean (black) athletes and the implications of black ethnicity on ECG-based screening are unknown. Black athletes appear susceptible to sudden death from hypertrophic cardiomyopathy (HCM), yet the phenotype of athletes with HCM and black HCM patients remain undefined. This thesis aimed to 1) characterise adolescent black athlete’s heart; 2) assess current and refined ECG screening criteria in black athletes; 3) define the phenotype of athletes with HCM; 4) define the phenotype and outcome in black HCM patients; 5) examine genetic mechanisms underlying black athletes’ heart. Subjects, Setting and Methodology: Athletes were recruited through pre-participation screening. HCM patients were recruited from three tertiary cardiomyopathy centres. Subjects underwent history, examination, ECG, echocardiography, exercise testing, Holter monitoring, cardiac MRI. Genetic testing was performed by a commercial company. Results and Conclusions: 1) Adolescent black athletes undergo similar electrical and structural changes to adult black athletes, with young males capable of developing significant hypertrophy. 2) Current ECG criteria result in almost half of black athletes failing pre-participation screening. Refinement of current criteria can significantly reduce false positive results whilst maintaining sensitivity to detect HCM. 3) Athletes with HCM exhibit more electrical changes but milder structural changes compared to sedentary patients. Apical HCM is common in athletes. Conventional discriminators between athlete’s heart and HCM perform poorly in athletes with HCM. 3 4) 30% of black HCM patients are diagnosed fortuitously and exhibit more ECG changes. Apical and concentric hypertrophy is commoner in black compared to white HCM patients but natural history similar. Hypertension is an independent predicator of adverse outcome. 5) T-wave inversion is not associated with a definitive pathogenic mutation for cardiomyopathy in the majority of black and white athletes. A Corin allele associated with hypertension and hypertrophy is commoner in black athletes and may explain their greater hypertrophy.