Backgroud: Left ventricular (LV) pressure–strain loops (PSLs) have been recently validated as a non-invasive index of myocardial performance. Aim of the present study is to compare average cardiac work (avgCW), positive work (avgPW), negative work (avgNW) and work efficiency (WE) in normal subjects (NOR) and in patients with severe primary mitral regurgitation (MR) and preserved left ventricular ejection fraction (LV EF). The standard deviation of the integrals of the strain peaks (SDpeak) was also used as a measure of energy dispersion during systole.
Methods: we included in this study 20 NOR and 20 MR patients (mean age: 43 ± 13 vs 65 ± 11 years). Strain traces and valvular event times were used for the calculation of LV-PSLs.
Results: no differences in LVEF (65 ± 4 vs 67 ± 6%, p=NS), GLS (-23% ± 2 vs -24 ± 3%, p=NS), avgCW (2130 ± 206 vs 2151 ± 405 mmHg%, p=NS), and avgPW (2338 ± 204 vs 2461 ± 392 mmHg/%, p=NS) were found between NOR and MR patients. With respect to NOR, MR patients showed a reduction in avgNW (96 ± 70vs174 ± 67 mmHg%, p=0.01) and an increased WE (96 ± 3 vs 92 ± 3, p=0.0001). Despite this, a slight but significant increase in energy dissipation during systole was observed in MR, as shown by the higher SDpeak (1.21 ± 0.33 vs 0.97 ± 0.25, p=0.01).
Conclusions: in patients with severe MR and normal LV performance, avgCW, and avgPW are preserved, with MR in the left atrium being probably responsible of the significant reduction in the LV avgNW. Despite this, a certain degree of dyssynchrony in LV segments activation was present, which explains increased the slightly energy dissipation during systole. Further studies on larger cohorts of patients are necessary to clarify the variation of these indexes in the different phases of the MR continuum and to evaluate their applicability in clinical practice.