3D ventricular stiffness versus systolic dysfunction: rethinking outcome predictors in dilated cardiomyopathy

Background and purpose Dilated cardiomyopathy (DCM), characterised by left ventricular (LV) dilation with impaired systolic function, is also associated with diastolic abnormalities, which contribute significantly to symptoms, disease progression and prognosis. Myocardial remodelling includes fibrosis and increased chamber stiffness, which impair LV relaxation and elevate filling pressures. We aimed to assess LV stiffness non-invasively using 3D echocardiography and to evaluate its prognostic role in a cohort of patients with DCM. Methods 121 consecutive patients with non-ischemic DCM underwent comprehensive 2D and 3D echocardiographic assessment, using dedicated software for 3D LV analysis. LV stiffness was defined as 100 * the mitral E/ lateral annular e' ratio divided by 3D LV end-diastolic volume. Patients were prospectively followed for 19±11 months for a composite endpoint of death or heart failure decompensation requiring hospitalisation. Results Mean age in the study group was 59±14 years and the majority (74%) were men. 55 patients reached the endoint: there were 26 deaths and 29 hospitalisations for heart failure. LV systolic dysfunction was similar between patients with and without events, with no significant differences in terms of LV stroke volume (p=0.88), LV ejection fraction (LVEF) (p=0.08) or LV global longitudinal strain (p=0.09). There were no differences in 3D LV end-diastolic volume (p=0.11), end-systolic volume (p=0.09) or 3D LVEF (p=0.22) between patients reaching and not reaching the endpoint. On the other hand, diastolic dysfunction was greater in patients with events: 1.7±0.8 vs. 1.2±0.7, p<0.001 for mitral E/A ratio, 118±51 ml vs. 88±45 ml, p=0.001 for LA volume. LVSI was higher in patients reaching the endpoint (7.5±4.3 vs. 6.0±2.6, p=0.02), reflecting greater LV stiffness. In Cox regression analysis, LVSI predicted adverse outcome (HR=1.11 [95% CI, 1.04–1.19], p=0.003), while LVEF did not (p=0.08). LVSI remained a independent predictor of events after adjusting for age, NYHA class, mitral regurgitation severity and pulmonary artery systolic pressure (HR=1.10 [95% CI, 1.02–1.18], p=0.01). Conclusions LV stiffness was greater in patients with DCM and adverse events, reflecting a more impaired diastolic dysfunction. LVSI was an independent outcome predictor in survival analysis, while LV systolic dysfunction was not.