How low is "low-flow" in aortic stenosis? A retrospective analysis of patients with true low-flow/low-gradient aortic stenosis undergoing TAVI. - Kücken T; Edlinger C; Okamoto M; Bannehr M; Jirak P; Lichtenauer M; Haase-Fielitz A; Krizanic F; Butter C (Minerva medica, 2021)