Hemodynamic and prognostic implications of net atrioventricular compliance in patients with mitral stenosis

On the basis of the close association of left atrial compliance with pulmonary hypertension in patients with mitral stenosis, we hypothesized that: (1) Doppler-derived net atrioventricular compliance (C(n)) can be used for predicting the occurrence of mitral valve (MV) replacement or percutaneous mitral commissurotomy (PMC); and (2) determinants of exercise capacity are variable depending on C(n).

We consecutively enrolled 26 patients (22 women; mean age, 47.0 +/- 6.1 years; range, 35-59 years) with pure moderate or severe mitral stenosis, in whom comprehensive echocardiography was performed at rest. C(n) was derived from the equation that has been previously validated (ie, C(n) = 1270 x [MV area by 2-dimensional planimetry/mitral E-wave downslope]. Measurements of stroke volume and systolic pulmonary artery pressure were repeated immediately after symptom-limited treadmill exercise test within 60 seconds.

On the basis of earlier reports, C(n) less than 4 mL/mm Hg was selected to define abnormally small C(n). During a mean duration of 24-month follow-up, C(n) of less than 4 mL/mm Hg could reliably predict the occurrence of either MV replacement or PMC, which was confirmed by multivariate logistic regression analysis. In patients with C(n) less than 4 mL/mm Hg, exercise duration was found to be closely correlated primarily with resting systolic pulmonary artery pressure (r = -0.73, P = .03), whereas in patients with C(n) greater than or equal to 4 mL/mm Hg, postexercise stroke volume was the only determinant of exercise capacity (r = 0.49, P = .04). When combining C(n) less than 4 mL/mm Hg with MV area less than 1.0 cm(2) as a cut-off value for predicting MV replacement or PMC, the sensitivity improved from 63.6% to 81.8% (P = .05).

Left atrial compliance estimated by C(n) with Doppler echocardiography allows us to effectively predict the future occurrence of MV replacement or PMC, with a special usefulness in patients with moderate mitral stenosis. In addition, determinants of exercise capacity were variable depending on the degree of C(n).