Temporal changes in left ventricular function and paravalvular aortic regurgitation after transcatheter aortic valve implantation: a cardiac magnetic resonance imaging study by Merten Constanze, Beurich Hans-Wilko, Zachow Dirk, Mostafa Ahmad E, Gordian Ken, Toelg Ralph, Geist Volker, Abdel-Wahab Mohamed, Richardt Gert H