Results

The search terms yielded 26,782 manuscripts and were ranked in descending order of total citations. The 100 top-ranked manuscripts had a total of 76,680 citations and are shown in Table 1 . The list of manuscripts is ordered from most to least cited on PubMed.gov.[6] The number of citations ranged from 3667 to 350, with a mean and median citation count of 767 and 533 respectively. The manuscripts were published across 16 journals shown in Table 2 .
The journal New England Journal of Medicine (NEJM) had the highest impact factors and generated the highest number of citations, of 22,458 with 18 manuscripts. This is followed by Circulation with the highest number of manuscripts, of 24, generating 14,719 citations. The latest manuscript was on management guidelines for valvular heart diseases by the European Society of Cardiology published in 2017 issue of European Heart Journal . The oldest manuscript was published in Lancet in 1986 comparing percutaneous valvuloplasty against valve replacement in patients with aortic stenosis.
The country with the most citations was the United States of America, with 43,629 citations across 51 manuscripts. This is followed by France and Canada, with 13,750 and 6579 citations respectively, generated by a total of 26 manuscripts. Citations counts by country are shown inFigure 1 .
Of the top 10 authors, five have more than three authorships in the top 100 manuscripts (Table 3 ). 8 of the top 10 cited authors have multiple manuscripts and altogether generated a total of 36,578 citations. Nashimura had the most manuscripts in the top 100 (n=6), totalling 4,583 citations. Vahanian generated the highest citation count of 5,178 from four manuscripts in addition to being the senior author of two other manuscripts within the top 100.
Of the top 100 manuscripts, 33 investigated aortic valve replacement for both aortic regurgitation and stenosis whereas 32 were specific to aortic stenosis alone, accumulating 33,336 and 22,638 citations respectively. 29 manuscripts focussed specifically on the outcomes of percutaneous or transcatheter approach to aortic valve replacement, amounting to 20,702 citations. 18 of the top 100 were management guidelines involving aortic valve replacement, resulting in 17,585 citations. Topics by citation are shown in Table 4 .