P1088Match and mismatch between opening area and resistance in mild and moderate rheumatic mitral stenosis.

BACKGROUND

Mitral valve resistance (MVR) is a hemodynamic consequence of mitral stenosis but it has no clear threshold and it has a shortage of data to be reliable.

PURPOSE

is to investigate match and mismatch between opening area and resistance especially in patients with moderate and mild mitral stenosis.

MATERIALS

This cross section case control study comprised 88 patients with moderate and mild rheumatic mitral stenosis. Transthorathic echocardiographic study estimated: mitral valve area (MVA) both by planimerty (2D) and pressure half time (PHT), mitral valve score (MVS), mean transmitral pressure gradient (MPG), diastolic filling time(DFT), left ventricular out flow tract diameter (LVOTd) and velocity time integral (LVOT vti) , the MVR was calculated as: MPG/aortic flow ratio [(LVOTd) (LVOTvti)/ DFT] in dynes.sec.cm5, NYHA function class of all patients was estimated. We classified our patients into 2 groups, group 1 (51 patients) with matched MVR and group 2 (37 patients) with unmatched MVR (unexpected high MVR in relation to valve area).

METHODS

Patients with moderate mitral stenosis have MVR less than 105 dynes.sec/cm5, while patient with mild mitral stenosis have MVR less than 76 dynes.sec/cm5 this is in the matched group, but there are patients with unmatched higher MVR. Group 2 compared to group 1; had higher NYHA function class (1.4±0.6 vs. 1.2±0.4, P < 0.05), MVS (8.1±1.8 vs 7±0.9, P < 0.05), MPG (11,3±3.7 vs.7.8±2.5 mmHg, P < 0.01) and higher MVR (122.37±29.87 vs. 67.18±20.12 dynes.sec/cm5 , P < 0.01), MVR showed positive correlation with MVS (r=0.5, P < 0.05), Step wise logistic regression analysis showed that MVS is the only independent predictor of the MVR severity in the mismatched (unexpected high) group , so the higher the MVS the higher the expected MVR whatever the MVA is ; (B±SE=6.997±2.826, t=2.476, 95% CI 1.241±12.752 with an odds ratio=0.412, P < 0.05).

CONCLUSION

It would make much more sense to investigate match and mismatch between opening area and resistance in rheumatic mitral stenosis, the only independent predictor of mismatch is the mitral valve score.