Combined Assessment with Myocardial Contractility and an Index Related to Ventricular Afterload in Patients with Isolated Severe Mitral Regurgitation Undergoing Valve Replacement. A Retrospective Study.

The afterload to the left ventricle increases following valve replacement in chronic mitral regurgitation (MR), yet there has been no study taking into account left ventricular (LV) afterload. In 43 patients with isolated chronic MR undergoing mitral valve replacement (MVR), we calculated LV wall stress using preoperative LV end-diastolic dimensions and diastolic aortic pressure (predictive LV wall stress = pWS). This value would represent LV wall stress at the instant of aortic valve opening immediately after MVR, assuming that LV end-diastolic dimensions and the aortic pressure did not change after operation. We also calculated end-systolic wall stress/volume index (ESS/ESVI) ratio, an index of myocardial function. None of 15 patients with the ESS/ESVI ratio > 1.6 had postoperative mortality or morbidity, whereas among the 26 patients with the ESS/ESVI ratio < 1.6, 12 patients had mortality (3 patients) and/or morbidity requiring intraaortic balloon pumping or prolonged catecholamine support. Three patients who died had pWS > 200 kdynes/cm2. Including these 3, all 5 patients whose pWS > 200 had mortality or severe morbidity immediately after surgery. In contrast, among the 38 patients with lower pWS, none died and only 7 patients (18%) had morbidity. Thus, patients who had a low contractility index and a high predictive afterload value had high mortality and morbidity. We conclude that the prediction of postoperative mortality and morbidity is improved by combined assessment of myocardial function and the hypothetical postoperative LV afterload.