Funding for this research was provided by:
British Heart Foundation (FS/15/70/32044, PG/13/86/30546, RG/13/16/30528)
Received: 18 September 2018
Accepted: 23 November 2018
First Online: 7 December 2018
Ethics approval and consent to participate
: Participants provided informed written consent to the investigation. Ethical approval was obtained from the National Research Ethics Service (NRES) Committee London.
: Not applicable.
: The author declare that they have no competing interests.
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