Prognostic Implications of Left Ventricular Myocardial Work Indices in Patients With Secondary Mitral Regurgitation

Abstract

Background: Assessment of left ventricular (LV) function in patients with secondary mitral regurgitation (SMR) remains challenging but is an important parameter for risk stratification. The association of LV myocardial work components (work index [GWI], constructive [GCW] and wasted [GWW] work, and work efficiency) derived from pressure-strain loops obtained with speckle tracking echocardiography, and all-cause mortality in patients with SMR was investigated. Methods: LV myocardial GWI, GCW, GWW, and global work efficiency were measured with speckle tracking strain echocardiography in 373 patients (72% men, median age 68 years) with various grades of SMR. All-cause mortality was the primary end point. Results: Mild SMR was observed in 143 patients, 128 had moderate SMR, and 102 had severe SMR. Patients with severe SMR had the largest LV volumes and the worst LV ejection fraction and LV global longitudinal strain. In patients with severe SMR, LV GWI and GCW were more impaired (500 mm Hg% versus 680 mm Hg% P =0.024 and 678 mm Hg% versus 851 mm Hg% P =0.006, respectively), while GWW was lower (130 mm Hg% versus 260 mm Hg% P <0.001, respectively) and global work efficiency was significantly higher (82% versus 76%, P =0.001) compared with patients with mild SMR. After a median follow-up of 56 months, 161 patients died. LV GWI≤500 mm Hg%, LV GCW≤750 mm Hg%, and LV GWW<300 mm Hg% were independently associated with excess mortality. Conclusions: Patients with severe SMR had the worst LV GWI and LV GCW but better LV GWW and global work efficiency reflecting the unloading of the LV in the low-pressure left atrial chamber. These parameters were independently associated with worse long-term survival in patients with SMR.