Impaired left ventricular contractile function in patients with long-term mitral regurgitation and normal ejection fraction

Objectives. We tested the hypotheses that left ventricular chamber elastance would detect impaired contractile function in patients with long-term mitral regurgitation and a normal ejection fraction and that these patients would have unique temporal left ventricular size and ejection fraction responses to mitral valve surgery. Background. Although it has been suggested that left ventricular contractile function may begin deteriorating in patients with long-term mitral regurgitation whereas ejection fraction remains normal, no data exist in humans. Methods. We studied 11 control patients and 28 patients with long-term mitral regurgitation using micromanometer-measured pressures, biplane contrast cineventriculography and radionuclide angiography under control conditions and with alterations in load during right atrial pacing to calculate left ventricular chamber elastance and myocardial stiffness. Results. The patients with mitral regurgitation were classified into subgroups: Group I, normal contractile function; Group II, impaired contractile function (reduced Emax) but normal ejection fraction, and Group III, impaired contractile function (reduced Emax) with reduced systolic myocardial stiffness. Twenty-two of the patients with mitral regurgitation underwent mitral valve surgery. In Group I, comparable decreases in left ventricular volume indexes (p < 0.01 and p = 0.05, respectively) were associated with no change in ejection fraction at 3 months and 1 year. In contrast, in Group II, reductions in volume indexes (p < 0.0001 and p < 0.001) were associated with a short-term decrease in ejection fraction (p < 0.001) that recovered at 1 year (p < 0.01 vs. short-term). Finally, in Group III, variable responses in volume indexes were associated with a consistent decrease in ejection fraction at 3 months and 1 year. Conclusions. An analysis of left ventricular chamber elastance provides data to support the concepts that 1) contractile function is impaired in some patients with long-term mitral regurgitation and a normal ejection fraction, 2) impaired contractile function may not be irreversible in all of these patients, and 3) an earlier consideration of mitral valve surgery may be warranted to preserve contractile function in these patients.