Investigating the Prevalence and Clinical Impact of Patient-Prosthesis Mismatch in Surgical Aortic Valve Replacement

L. Nam¹, R. Singh², V. Nguyen³, A. Osho², A. Jassar⁴, D. D'Alessandro⁵, T. Sundt⁶, J. P.. Bloom^6
1Massachusetts General Hospital, Somerville, Massachusetts ²Massachusetts General Hospital - Division of Cardiac Surgery, Boston, Massachusetts ³Harvard Medical School, Boston, Massachusetts ⁴Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts ⁵Massachusetts General Hospital - Division of Cardiac Surgery, Cambridge, Massachusetts ⁶Corrigan Minehan Heart Center, Division of Cardiac Surgery, Massachusetts General Hospital, Boston, Massachusetts

Purpose: This study investigates the impact of patient-prosthesis mismatch (PPM) on clinical outcomes and life expectancy in patients undergoing surgical aortic valve replacement (SAVR) at a high-volume institution. By conducting a retrospective review, we seek to illustrate how modern strategies have evolved to mitigate PPM and improve patient outcomes.

Methods: All patients who underwent SAVR, in isolation or with another cardiac procedure at a single institution were included. Excluded were those with missing valve sizes or models. PPM was calculated using effective orifice area (EOA) based on normal reference values for each prosthesis size and model and indexed to body surface area (EOAi). PPM was classified as moderate (EOAi ≤0.85 cm2/m2) or severe (EOAi ≤0.65 cm2/m2). Both mechanical and bioprosthetic valves were considered, and data was further stratified by bileaflet and trileaflet valve anatomy. To assess the prevalence of PPM over time, data was compared by decades, and the rate of those undergoing aortic root enlargement and the valve size used were also assessed. Primary endpoints included 30-day mortality, stroke, renal failure, dialysis, atrial fibrillation, and other morbidities. Statistical analysis was performed using Python, with significance set at P < 0.05.

Results: 5,444 patients underwent SAVR from July 2002 – December 2023. Overall, 3,545 patients (65.1%) had no PPM, 1,716 (31.5%) had moderate PPM, and 183 (3.3%) had severe PPM. However, over the most recent decade (2013-2023), 29% of patients experienced PPM, an improvement from 43% in the previous decade (P < 0.05). Furthermore, there is an increase in patients undergoing aortic root enlargement (7%), compared to the previous decade (3%), which correlated with an increased rate of patients without PPM (57% vs. 32.8%, P < 0.05). Additionally, the implanted valve size over the past decade was larger than the previous decade (24mm vs. 23mm, P < 0.05). Overall, severe PPM was associated with higher preoperative comorbidities such as diabetes, hypertension, atrial fibrillation, and advanced NYHA heart failure classification (P < 0.05). Patients with severe (4.2%) and moderate PPM (5.7%) exhibited higher 30-day mortality compared to those without PPM (2.7%, P < 0.05). No significant differences were observed in the rates of stroke, renal failure, atrial fibrillation, ICU stay, or ventilator time between PPM and non-PPM groups. Stratification by valve anatomy revealed that trileaflet valves showed a higher incidence of moderate and severe PPM (P < 0.05).

Conclusion: Our data shows a significant improvement in PPM rates over the last decade compared to the previous (29% vs. 43%), compared to the overall prevalence of 40-45% of PPM in literature. This emphasizes the importance of larger valves, annular enlargement, and other surgical techniques to improve PPM in the modern era.

Identify the source of the funding for this research project: None