Effects of Valve Surgery on Left Ventricular Contractile Function in Patients With Long-term Mitral Regurgitation

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Abstract
Background Patients with long-term mitral regurgitation were studied both before and 1 year after successful valve surgery to test the hypothesis that impaired left ventricular contractile function improves after surgery for long-term mitral regurgitation in humans. Methods and Results Fifteen patients with long-term mitral regurgitation were studied. Micromanometer left ventricular pressures and radionuclide angiograms for left ventricular volumes were acquired over a range of loading conditions both before and 1 year after successful valve surgery for long-term mitral regurgitation. To assess both left ventricular contractility and pump efficiency, we used left ventriculoarterial coupling to evaluate the interaction of the left ventricle with the arterial system with the use of the left ventricular contractile index, E es , and effective arterial elastance, E a . Left ventricular pump efficiency was expressed as the ratio of forward left ventricular stroke work to the corresponding pressure–volume area. All patients had successful mitral valve surgery as manifest by no or only trivial residual mitral regurgitation on physical examination and Doppler echocardiography. The average radionuclide regurgitant index of 1.28±0.56 was also less than the preoperative value of 2.70±0.80 ( P <.0001). The mean left ventricular end-diastolic volume index decreased from 137±37 to 90±31 mL/m 2 ( P <.001), and the average left ventricular end-systolic volume index also decreased (59±29 to 45±27 mL/m 2 , P <.01), although individual variation was observed. The average left ventricular ejection fraction fell from 0.58±0.12 to 0.53±0.16, which was not significant. In contrast, E es increased from a mean value of 0.95±0.66 mm Hg/mL during the preoperative study to 2.62±2.16 mm Hg/mL at the 1-year postsurgical study ( P <.01). This improvement in left ventricular contractility was observed in patients with long-term mitral regurgitation, who before surgery had preserved left ventricular ejection fraction ( P <.001), less left ventricular dilation at end diastole ( P <.01) and end systole ( P <.001), and less impaired left ventricular contractility. Because effective arterial elastance was unchanged, left ventriculoarterial coupling also improved from an average of 0.47±0.39 to 1.81±1.63 ( P <.01). Consequently, left ventricular pump efficiency improved from a mean preoperative value of 0.23±0.10 to 0.55±0.22 at the 1-year postsurgical study ( P <.0001). Conclusions The results indicate that left ventricular contractile impairment is reversible in many patients with long-term mitral regurgitation. In fact, these data indicate that mitral valve surgery can be recommended to preserve left ventricular contractility in patients with long-term mitral regurgitation, particularly in those patients who before surgery have normal left ventricular ejection fractions and less left ventricular dilation and contractile impairment.

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