Prosthesis patient mismatch in aortic valve replacement: possible but pertinent?The opinions expressed in this article are not necessarily those of the Editors of the European Heart Journal or of the European Society of Cardiology.

Aortic valve replacement (AVR) is now the second most commonly performed cardiac operation and with an increasingly elderly population, the number of such procedures will inevitably continue to grow. 1 In 1978, Rahimtoola 2 defined the term prosthesis patient mismatch (PPM) to describe the situation in which the effective orifice area (EOA) of a prosthetic valve, after implantation, is smaller than that of the native valve. Although described nearly three decades ago, there are several reasons why PPM has only more recently become much more openly debated. First, PPM was initially overshadowed by the more immediate issues of operative mortality and major morbidity. Second, by definition, all prosthetic valves must therefore have at least some degree of PPM; over 90% of AVR still use prostheses with a sewing ring, or have struts, hinge mechanisms, and rigid carbon or relatively stiff bioprosthetic leaflets. Third, and most importantly, as moderate aortic stenosis can be tolerated over long periods with excellent functional status and well-preserved ventricular function, the clinical relevance of all but the most severe PPM has remained uncertain.