Functional mitral stenosis after surgical annuloplasty for ischemic mitral regurgitation: importance of subvalvular tethering in the mechanism and dynamic deterioration during exertion.
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 cm(2) vs 5.2 +/- 0.6 cm(2), not significant), mitral valve area was significantly smaller than the annular area in patients after annuloplasty (1.6 +/- 0.2 cm(2) vs 3.3 +/- 0.5 cm(2), P < .01). The mitral valve area was less than 1.5 cm(2) only after the surgery (P < .01) and was significantly correlated with restricted leaflet opening (r(2) = 0.74, P < .001), left ventricular dilatation (r(2) = 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 cm(2) to 1.4 +/- 0.2 cm(2), 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.
Kubota
Kayoko
K
Department of Cardiovascular Medicine, Graduate School of Medicine, Kagoshima University, Kagoshima, Japan.
Otsuji
Yutaka
Y
Ueno
Tetsuya
T
Koriyama
Chihaya
C
Levine
Robert A
RA
Sakata
Ryuzo
R
Tei
Chuwa
C
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019917:Blood Vessel Prosthesis Implantation / Q000009:adverse effects*; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D018618:Echocardiography, Doppler, Color; D025401:Echocardiography, Stress; D005260:Female; D006801:Humans; D007564:Japan; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D008944:Mitral Valve Insufficiency / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology / Q000601:surgery*; D008946:Mitral Valve Stenosis / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology; D017202:Myocardial Ischemia / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D005082:Physical Exertion; D018570:Risk Assessment; D012307:Risk Factors; D016896:Treatment Outcome; D016277:Ventricular Function, Left; D020257:Ventricular Remodeling