Functional mitral stenosis after surgical annuloplasty for ischemic mitral regurgitation: Importance of subvalvular tethering in the mechanism and dynamic deterioration during exertion
Received 12 March 2009; received in revised form 15 September 2009; accepted 2 November 2009. published online 01 February 2010.
Objective
Diastolic subvalvular mitral leaflet tethering by left ventricular remodeling that restricts leaflet opening in the presence of annular size reduction by surgery for ischemic mitral regurgitation potentially causes functional mitral stenosis in the absence of organic leaflet lesions. Exercise, known to worsen systolic tethering and ischemic mitral regurgitation, might also dynamically exacerbate such mitral stenosis by increasing tethering. This study evaluates the mechanism and response of such mitral stenosis to exercise.
Methods
We measured the diastolic mitral valve area, annular area, and peak and mean transmitral pressure gradient by echocardiography in 20 healthy individuals and 31 patients who underwent surgical annuloplasty for ischemic mitral regurgitation.
Results
Although the mitral valve area and annular area did not significantly differ in healthy individuals (4.7 ± 0.6 cm2 vs 5.2 ± 0.6 cm2, not significant), mitral valve area was significantly smaller than the annular area in patients after annuloplasty (1.6 ± 0.2 cm2 vs 3.3 ± 0.5 cm2, P < .01). The mitral valve area was less than 1.5 cm2 only after the surgery (P < .01) and was significantly correlated with restricted leaflet opening (r2 = 0.74, P < .001), left ventricular dilatation (r2 = 0.17, P < .05), and New York Heart Association functional class (P < .05). Exercise stress echocardiography of 12 patients demonstrated dynamic worsening in functional mitral stenosis (mitral valve area: 2.0 ± 0.5 cm2 to 1.4 ± 0.2 cm2, P < .01; mean pressure gradient: 1.5 ± 0.9 mm Hg to 6.0 ± 2.2 mm Hg, P < .01).
Conclusions
Persistent subvalvular leaflet tethering in the presence of annular size reduction by surgery in ischemic mitral regurgitation frequently causes functional mitral stenosis at the leaflet tip level, which is related to heart failure symptoms and can be dynamic with significant exercise-induced worsening.
aDepartment of Cardiovascular Medicine, Graduate School of Medicine, Kagoshima University, Kagoshima, Japan
bDepartment of Cardiovascular Surgery, Graduate School of Medicine, Kagoshima University, Kagoshima, Japan
cDepartment of Public Health, Graduate School of Medicine, Kagoshima University, Kagoshima, Japan
dSecond Department of Internal Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
eMassachusetts General Hospital, Boston, Massachusetts
Address for reprints: Yutaka Otsuji, MD, Second Department of Internal Medicine, School of Medicine, University of Occupational and Environmental Health, Iseigaoka 1-1, Yahatanishi-ku, Kitakyushu 807-8555, Japan.
Dr Otsuji was supported by Grants-in-Aid for Scientific Research 19500431 and 21500458 from the Japan Society for the Promotion of Science, Tokyo, Japan.
ABSTRACT