Atrial functional mitral regurgitation: cardiac remodeling and outcome after mini-thoracotomy mitral valve surgery.

BACKGROUND

The atrial functional mitral regurgitation (AFMR) refers to a newly recognized disease entity in which mitral regurgitation occurs secondary to left atrial (LA) disease, without left ventricular (LV) dilatation and dysfunction (at least initially) and intrinsic mitral valve (MV) disease.

METHODS

We conducted an observational analysis on 28 subjects, mean age and standard deviation 72.7±8.4 years, with AFMR who underwent mini-thoracotomy MV surgery (mitral annuloplasty and tricuspid ring annuloplasty when needed). No surgical treatment of atrial fibrillation (AF) has been performed.

RESULTS

There was no in-hospital mortality. At one-year follow-up, we observe a reverse remodeling of the LV and LA, with a significant reduction of the end-diastolic volume of the LV (110 mL [95-148 mL] vs. 55 mL [48-59 mL], z: -0.7, P<0.001), of antero-posterior (A-P) diameter of left atrium (50 mm [38-60] vs. 46 mm [35-55], z: -3.3, P<0.01) and volume (83.5 mL [63.2-96.5 mL] vs. 63 mL [45.5-78.7 mL], z: -3.2, P<0.01), of the estimated systolic pulmonary artery pressure (PAP) (35 mmHg [30-43] vs. 25 [22-32.7], z: -3.9, P<0.001). Results were not altered by the presence or absence of AF. The overall 1-year survival rates were 100% and all the patients recovered to NYHA functional class I/II at the end of follow-up (z: -6, P<0.001).

CONCLUSIONS

The results of our small study showed that mini-thoracotomy valve surgery for AFMR is safe and effective. It improves functional class (NYHA) and results in reverse-remodeling of LA, regardless of the presence or absence of AF. A reduction in left ventricular volumes was also observed, although baseline volumes were still within normal limits, as an expression of reduction in left ventricular overload. Mitral insufficiency should be the primary target of treatment, while AF appears to be an epiphenomenon rather than a causal element of AFMR.