Abstract 2862: Age is an Independent Effect Modifier of Prosthesis-Patient Mismatch in Patients Undergoing Aortic Valve Replacement
Objectives: Prosthesis-patient mismatch (PPM) after aortic valve replacement (AVR) may have consequences in certain patient subgroups and not in others. Recent data suggest that age may represent one of these effect modifiers; however, no series has yet examined the impact of age in a pure aortic stenosis (AS) population and accounted for left ventricular (LV) function and co-morbid factors.
Methods: Detailed annual clinical and echocardiographic assessments were performed in 707 patients who had AVR for pure AS over a period extending to 14 years (median 5.8 years). Patients were double stratified into i) less than 70 years of age and 70 years or older, and ii) into those with preoperative LV ejection fraction >=50% (“normal”) and <50% (“impaired”). PPM was defined as an in vivo indexed Effective Orifice Area (iEOA) ≤0.85 cm2/m2. The effects of PPM on survival, freedom from heart failure (CHF) or CHF death, and LV mass regression were examined with bootstrapped multivariable techniques.
Results: Mismatch did not independently impact the survival of AS patients with normal LV, regardless of age (for <70 years: hazard ratio 2.0±1.2, P=0.2; for ≥70 years: hazard ratio 1.6±1.4, P=0.6). However, in patients with impaired LV, PPM significantly affected the survival of patients under 70 years of age, but not that of patients 70 years or older (see figures). PPM increased the likelihood of CHF symptoms of CHF death by 5 years after AVR if patients were under 70 years old and had an impaired LV (odds-ratio 7.2±6.1, P=0.02); this effect of PPM was not observed in patients 70 years or older. Conversely, indexed LV mass regression was more impaired by PPM in patients 70 years or older (by 30±9 g/m2, P=0.001) than in younger patients, in whom coronary disease (37±13 g/m2, P=0.005) was a stronger determinant of incomplete LV mass regression.
Conclusions: Prosthesis-patient mismatch needs to be avoided in patients under 70 years of age with impaired LV function, due to its impact on survival and functional status. In patients 70 years or older, PPM appears to impair LV mass regression, but with no significant effect on overall survival and functional status.