title: Authors' reply.
authors.affiliation: Cardiology Department, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge CB23 3RE, UK sergioncbarra@gmail.com.
authors.forename: Sérgio
authors.initials: S
authors.lastname: Barra
authors.affiliation: Cardiology Department, University College London Hospitals NHS Foundation Trust, London, UK.
authors.forename: Rui
authors.initials: R
authors.lastname: Providência
authors.affiliation: Cardiology Department, Coimbra Hospital and University Centre, Coimbra, Portugal.
authors.forename: Luís
authors.initials: L
authors.lastname: Paiva
authors.affiliation: Cardiology Department, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge CB23 3RE, UK.
authors.forename: Patrick
authors.initials: P
authors.lastname: Heck
authors.affiliation: Cardiology Department, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge CB23 3RE, UK.
authors.forename: Sharad
authors.initials: S
authors.lastname: Agarwal
mesh_terms: D001145:Arrhythmias, Cardiac / Q000628:therapy*; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D016757:Death, Sudden, Cardiac / Q000517:prevention & control*; D017147:Defibrillators, Implantable; D006801:Humans; D018579:Patient Selection