A Prospective Study of Comparison of Left Ventricular Volumes and Function by 2D and 3D Transthoracic...

Accurate assessment of left ventricular ejection fraction (LVEF) and volumes is pivotal for stratifying heart‑failure severity and guiding device or revascularisation therapy. Two‑dimensional echocardiography (2DE) is ubiquitous, yet geometric assumptions impair precision. Three‑dimensional echocardiography (3DE) offers improved spatial resolution, but its added value in routine practice is under‑reported.

The objectives of this study were to compare 2DE‑ and 3DE‑derived LVEF and volumes in heart failure with reduced ejection fraction, quantify reclassification rates (patients whose classification of the severity of LV systolic dysfunction changes between 2DE and 3DE), and identify subgroups benefiting most from 3DE (e.g., patients having moderate LV systolic dysfunction by 2DE who were found to have severe LV systolic dysfunction by 3DE were advised for implantable cardioverter-defibrillator or cardiac resynchronisation therapy).

This prospective observational study enrolled 104 patients with left ventricular systolic dysfunction (ejection fraction (EF) <50%) at Kalinga Institute of Medical Sciences between March 2020 and September 2022. Two-dimensional (2D) and three-dimensional (3D) transthoracic echocardiography (TTE) were performed using a Philips Epiq™ 7 system with S5-1 and X5-1 transducers, respectively. LV volumes and EF were measured using Simpson's biplane and Teichholz methods for 2DE, and full-volume acquisition for 3DE. Visual EF estimation ("eyeballing") was also recorded. Intra-modality and inter-modality comparisons were analysed using paired t-tests, Pearson correlation coefficients, and Bland-Altman plots.

Three-dimensional datasets were successfully acquired in 102 (98.1%) of 104 patients. The mean age was 56.4±11.5 years, with 72 (69.2%) male patients. EF measured by 3DE (34.8±11.9%) was significantly lower compared to that measured by 2D Teichholz (37±10.4%) and Simpson's method (37.1±12.8%; p<0.001). Eyeballing EF (34.9±10.1%) showed the strongest correlation with 3DE (r=0.701). Strong correlations were observed between 3DE- and 2DE-derived volumes (end-diastolic volume (EDV) r=0.82-0.83; end-systolic volume (ESV) r=0.83-0.86), though Bland-Altman analysis showed wide limits of agreement. 3DE reclassified 17 (43.5%) of 39 patients with moderate LV systolic dysfunction by 2DE into the severe dysfunction category. Regional wall motion abnormality (RWMA) was identified in 69 (67.6%) patients by 3DE versus 39 (38.5%) by 2DE. Correlation between 2DE and 3DE was better in patients with global hypokinesia than in those with RWMA. Image acquisition and analysis averaged 23.1±3.8 minutes.

Adding 3DE to routine 2DE refines quantification of LVEF, ventricular volumes, and regional function, reclassifying nearly half of borderline cases and potentially altering defibrillator or resynchronisation therapy recommendations. Where 3DE is unavailable, expert visual estimation outperforms formula‑based 2DE in approximating 3DE accuracy and risk stratification in daily practice.