Background: Left ventricular ejection fraction (LVEF) has prognostic value and is used to guide medical treatment and device implantation. The preferred technique is two-dimensional echo (2DE), although three-dimensional echo (3DE) is more accurate when compared to cardiac magnetic resonance imaging. Our study evaluates the agreement between 2D and 3D LVEF and the potential clinical impact of disagreements. Methods: Participants ≥50 years were included from the Copenhagen City Heart Study. Means of difference (MD) between 2D and 3D volumes and LVEF were assessed, Cox regression models were used to estimate the association between 2D and 3D LVEF <40% and outcome. 3DE were used as reference. Results: In all 1606 participants were included. Median age was 65.4 (IQR: 57.89‒73.6) and 702 (43.7%) were males. Median follow-up was 5.5 (IQR: 4.72‒6.3) in which 102 (6.4%) died and 142 (8.8%) experienced a major adverse cardiovascular event (MACE) and 194 (12.1%) any cardiovascular event. The MD between 2D and 3D LVEF as the LV deteriorated the LV got (LVEF <40%, MD: -14.4 (-15.9 ‒ -13.0) vs. LVEF 40-49% -9.2 (-9.8 ‒ -8.7) vs. LVEF >50%, MD: -0.96 (-1.4 ‒ -0.51)). 3D LVEF <40% was significantly associated with all outcomes (2.85 (95% CI: 1.64‒4.95), (all-cause mortality), 2.71 (95% CI: 1.68‒4.36), (MACE) and 2.41 (95% CI: 1.68‒4.36) (any cardiovascular event). 2D LVEF <40% was only associated to MACE 2.69 (95% CI: 1.25‒5.77). 2DE misclassified (defined as ≥10 percentage units of difference between 2D and 3d LVEF) LVEFs in 508 (31.6%) of all exams. Conclusion: In this population study in low-risk subjects, only 3D LVEF was associated with excess mortality, whereas 2D LVEF was not.

The main direction of left ventricular (LV) contraction is based on the different architecture of myocardial fibers. Thus, it can be assumed that the specific analysis of different compounds of LV deformation might be a crucial diagnostic tool in patients with infective myocarditis (IM). This case report focusses on conspicuous findings of regional LV deformation in a patient with IM and preserved LV systolic function. Despite unspecific clinical symptoms in IM, e.g. subfebrile temperatures, cough, palpitations, suspect findings of circumferential and rotational deformation can be helpful to initiate further diagnostic procedures to confirm the diagnosis, e.g. cMRI or myocardial biopsy.