RT Journal Article SR Electronic T1 Cardiac resynchronisation therapy upgrade and occurrence of ventricular arrhythmia JF Heart JO Heart FD BMJ Publishing Group Ltd and British Cardiovascular Society SP 793 OP 793 DO 10.1136/hrt.2008.145078 VO 94 IS 6 A1 J G F Cleland A1 D Cullington A1 A Tageldien Abdellah YR 2008 UL http://heart.bmj.com/content/94/6/793.1.abstract AB