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Mitral Valve Area After Restrictive Annuloplasty | Journal Scan
Study Questions:
What is the hemodynamic and clinical impact of effective orifice area (EOA) after restrictive mitral valve annuloplasty (RMA), and its relationship with diastolic anterior leaflet (AL) tethering at rest and during exercise?
Methods:
Consecutive RMA patients (n = 39) underwent a symptom-limited supine bicycle exercise test with Doppler echocardiography and respiratory gas analysis. EOA, transmitral flow rate, mean transmitral gradient (TMG), and systolic pulmonary arterial pressure (sPAP) were assessed at different stages of exercise. AL opening angles were measured at rest and peak exercise. Mortality and heart failure readmission data were collected during at least 20 months post-surgery.
Results:
EOA and AL opening angle were 1.5 ± 0.4 cm2 and 68 ± 10°, respectively, at rest (r = 0.4, p = 0.014). EOA increased significantly to 2.0 ± 0.5 cm2 at peak exercise (p < 0.001), showing an improved correlation with AL opening angle (r = 0.6, p < 0.001). Indexed EOA (EOAi) at peak exercise was an independent predictor of exercise capacity (maximal oxygen uptake, p = 0.004) and was independently associated with freedom from all-cause mortality or heart failure admission (p = 0.034). Patients with exercise EOAi <0.9 cm2/m2 (n = 14) compared to ≥0.9 cm2/m2 (n = 25) had a significantly worse outcome (p = 0.048). In multivariate analysis, AL opening angle at peak exercise (p = 0.037) was the strongest predictor of exercise EOAi.
Conclusions:
The authors concluded that indexed EOA at peak exercise is a strong and independent predictor of exercise capacity, and is associated with clinical outcome.
Perspective:
This study quantified the transmitral pressure-flow relationship in secondary mitral regurgitation (MR) patients treated with RMA, and demonstrated an increase in EOA during exercise. Furthermore, exercise EOAi was independently associated with outcome and was a stronger predictor of exercise capacity than was EOAi at rest, stressing the importance of exercise echocardiography in this patient population. These findings stress the importance of maximizing AL mobility by targeting the subvalvular apparatus in future repair algorithms for secondary MR. All efforts that could assure a durable repair while relieving tethering and increasing annuloplasty ring size should be the subject of additional research.
Keywords: Mitral Valve Annuloplasty, Echocardiography, Doppler, Exercise Test, Arterial Pressure, Heart Failure, Multivariate Analysis, Rest, Diastole, Systole
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