RT Journal Article SR Electronic T1 Aortic stenosis: service delivery before guidelines JF Heart JO Heart FD BMJ Publishing Group Ltd and British Cardiovascular Society SP 1686 OP 1687 DO 10.1136/heartjnl-2019-315606 VO 105 IS 22 A1 John B Chambers YR 2019 UL http://heart.bmj.com/content/105/22/1686.abstract AB