Prosthesis-patient mismatch due to small ring annuloplasty in patients with degenerative mitral insufficiency.

BACKGROUND

Avoidance of prosthesis-patient mismatch (PPM) is important when selecting a mitral valve prosthesis. This study investigated the effect of PPM after small ring mitral valve annuloplasty on postoperative hemodynamics and the clinical course.

METHODS

This study retrospectively reviewed 227 patients with symptomatic severe mitral insufficiency (MI) who underwent mitral valve repair for degenerative MI using an Edwards ring or band (size: 26-32mm) between 2003 and 2012. Echocardiography was performed postoperatively and at follow-up to evaluate cardiac function, including residual MI, mean transmitral pressure gradient, left atrial diameter (LAD), and tricuspid regurgitant pressure gradient (TRPG).

RESULTS

There were no operative deaths. Actuarial freedom from major adverse cardiac events was 91% at 10 years. The postoperative MI grade was not significantly different between different sizes of prosthesis (26mm, 0.67±0.8; 28mm, 0.73±0.9; 30mm, 0.85±0.9; 32mm, 0.3±0.6). LAD and TRPG were significantly lower for each size of prosthesis at follow-up (all p<0.05). Patients with a smaller body surface area received a significantly smaller prosthesis (p<0.05). The transmitral pressure gradient was significantly higher in patients with a 26-mm prosthesis than in patients with a larger size of prosthesis. Thirty-three patients had a follow-up transmitral pressure gradient ≥5mmHg. The follow-up LAD was larger in patients with a transmitral pressure gradient <5mmHg than in patients with that ≥5mmHg (43.2±9.4mm vs 47.1±9.6mm, p<0.05).

CONCLUSIONS

Mitral valve repair results in excellent clinical outcomes with significant reductions in MI, LAD, and TRPG for all sizes of prosthesis. However, use of a smaller prosthesis may result in a higher mean transmitral pressure gradient, and may inhibit reverse remodeling of the left atrium. Therefore, PPM should be avoided.