Progressive breathlessness following transcatheter aortic valve replacement

: An 84-year-old man presented urgently to the cardiology clinic with rapid onset exertional dyspnoea while walking on the flat. Five months previously, he underwent implantation of a balloon-expandable 26 mm transcatheter heart valve (SAPIEN 3, Edwards Lifesciences) for severe aortic stenosis. On clinical examination, the jugular venous pressure was elevated and a mid-late ejection systolic murmur was audible in the aortic region. ECG demonstrated sinus rhythm with a left ventricular (LV) strain pattern. Transthoracic echocardiography and cardiac CT were performed (figure 1). heartjnl;103/21/1703/F1F1F1Figure 1(A) Transthoracic continuous wave Doppler through the transcatheter AV. ECG-gated cardiac CT oblique reconstruction of the LV outflow tract and aortic root in mid-diastole (B) with axial reconstruction of the transcatheter AV in end-systole (inset). AT, acceleration time; AV, aortic valve; LV, left ventricular.

Which aetiology best explains this presentation?Pannus formationTranscatheter bioprosthetic valve endocarditisPatient-prosthesis mismatchTranscatheter bioprosthetic valve leaflet thrombosisStructural valve degeneration.