Noninvasive Assessment of Left Ventricular Stroke Work Index in Patients with Severe Mitral Regurgitation: Correlation with Invasive Measurement and Exercise Capacity

BACKGROUND: Noninvasively measured left ventricular stroke work index (LVSWI) may be an ideal indicator that can provide more relevant information about cardiac performance in severe mitral regurgitation (MR). We sought to correlate the noninvasive LVSWI with invasive measure of LVSWI and validate its clinical usefulness by comparing the noninvasive LVSWI with exercise capacity. METHODS: Twenty-nine patients with severe MR who underwent cardiac catheterization and 61 patients with severe MR who underwent cardiopulmonary exercise test were evaluated for comparison of noninvasive LVSWI with invasive LVSWI via cardiac catheterization and peak exercise capacity, respectively. RESULTS: Mean noninvasive LVSWI was 33.1 ± 9.7 g·m/m², which was in a good agreement with invasive LVSWI (34.9 ± 15.1 g·m/m², intraclass correlation coefficient = 0.72, P < 0.001). Noninvasive LVSWI (β= 0.35, P = 0.001) was independently related with peak exercise capacity. Indexed left atrial volume (β=-0.27, P = 0.042), mean blood pressure (β=-0.21, P = 0.030), age (β=-0.47, P < 0.001) estimated pulmonary artery systolic pressure (β=-0.21, P = 0.030) and male gender (β= 0.36, P = 0.001) were also independently associated with exercise capacity. CONCLUSIONS: Noninvasive LVSWI has a good correlation with invasively measured LVSWI and is a clinically useful parameter for evaluating true cardiac performance in patients with severe MR.