From the Guidelines
Distinguishing between patient prosthesis mismatch (PPM) and prosthetic valve stenosis requires a comprehensive diagnostic approach combining clinical assessment, echocardiography, and sometimes advanced imaging, with the most recent guidelines from 2021 emphasizing the importance of accurate diagnosis and treatment 1. To diagnose PPM and prosthetic valve stenosis, the following steps can be taken:
- Transthoracic echocardiography is the initial test, measuring effective orifice area indexed to body surface area (EOAi) and transvalvular gradients.
- PPM is diagnosed when high gradients occur with normal leaflet motion and EOAi <0.85 cm²/m² (moderate) or <0.65 cm²/m² (severe), typically present immediately after surgery.
- Prosthetic stenosis shows abnormal leaflet motion, thrombus, pannus, or calcification, with gradients increasing over time. The treatment approaches for PPM and prosthetic valve stenosis differ significantly:
- PPM is managed conservatively with cardiac rehabilitation, afterload reduction using ACE inhibitors or ARBs, and diuretics for symptom control, as recommended by the 2017 AHA/ACC guidelines 1.
- Reoperation is rarely indicated except in severe cases with significant symptoms.
- For prosthetic stenosis, treatment targets the underlying cause: anticoagulation optimization for thrombosis (with consideration of thrombolysis using tissue plasminogen activator for obstructive thrombus), while structural deterioration or pannus formation typically requires valve replacement, as outlined in the 2021 ACC/AHA guideline 1. The distinction between PPM and prosthetic valve stenosis is crucial, as PPM represents a size mismatch present from implantation, while stenosis is an acquired complication requiring specific interventions based on etiology, highlighting the importance of accurate diagnosis and treatment to improve patient outcomes and reduce morbidity and mortality.
From the Research
Diagnostic Approach
- Patient-prosthesis mismatch (PPM) and prosthetic valve stenosis can be diagnosed using echocardiography to assess the effective orifice area (EOA) of the prosthetic valve and the transvalvular gradient 2, 3.
- The indexed effective orifice area (iEOA) can be calculated to determine the presence of PPM, with a threshold of ≤0.65 cm²/m² for aortic valve prosthesis and ≤1.20 cm²/m² for mitral valve prosthesis 3.
- Multidetector CT (MDCT) can also be used to predict PPM by assessing the annular size and indexing it to the patient's body surface area 4.
Treatment Approach
- The treatment approach for PPM and prosthetic valve stenosis depends on the severity of the condition and the presence of symptoms 2, 3.
- For patients with severe PPM, redo surgery with implantation of a larger valve and/or annular enlargement may be considered if symptoms persist and are unresponsive to medical therapy 2.
- Strategies to mitigate the risk of PPM include accurate assessment of the patient's annular size and indexing the EOA of the prosthesis to the patient's body surface area at the time of prosthesis implantation 3.
- Aortic root replacement in patients with a small aortic annulus can also be used to prevent PPM 3.
Key Considerations
- PPM is associated with higher rates of perioperative stroke and renal failure, and lack of left ventricular mass regression 2.
- Predictors of PPM include female sex, older age, hypertension, diabetes, renal failure, and higher surgical risk score 2.
- The clinical outcome of PPM is associated with adverse cardiovascular events, especially in the presence of pre-existing left ventricle dysfunction or concomitant procedures such as coronary artery bypass graft surgery 3.
- Newer generation mechanical valves and stentless bioprosthesis have shown less PPM than older generation and stented prosthesis, respectively 3.