Left ventricular geometry and operative mortality in patients undergoing mitral valve replacement

Background: Distortion of left ventricular (LV) shape is often associated with LV dysfunction and is thought to be an independent predictor of survival in patients with coronary disease. Hypothesis: The purpose of this study was to examine the relationship between LV geometry and hospital mortality in patients with mitral regurgitation (MR) undergoing mitral valve surgery. Methods: A consecutive series of patients (aged 68 +/- 12 years, 47% men) (n = 149) with MR who underwent cardiac catheterization, left ventriculography, and mitral valve surgery from 1995 to 1996 at Mount Sinai Medical Center was studied. Left ventriculograms, clinical records, and hemodynamics were reviewed. Left ventricular volumes and ejection fraction were calculated using standard techniques. Left ventricular shape in diastole and systole was evaluated using the sphericity index, which is defined as the end-systolic LV volume (X 100) divided by the volume of a sphere whose diameter is equal to the LV long axis. Results: In the patients studied, the etiology of mitral insufficiency was mitral valve prolapse in 40.9%, ischemic heart disease in 40.3%, rheumatic heart disease in 11.4%, and prosthetic valvular dysfunction in 7.4%. The average ejection fraction was 65% +/- 17. Systolic sphericity index (SSI) was 36% +/- 15 in patients who died, compared with 25% +/- 11 in patients who lived (p < 0.001). A multivariate model was constructed using hemodynamic and angiographic indices derived during preoperative cardiac catheterization. Systolic sphericity index (odds ratio = 1.6 for each point increase, p < 0.01) was found to be an independent predictor of postoperative survival in the global population, as well as in patients with coronary disease (p < 0.01). Conclusion: Left ventricular geometry is an independent angiographic risk factor for survival following mitral valve replacement. Sphericity index is a simple method for assessing LV geometry which should be calculated in patients as part of risk stratification.