What is the clinical evidence from this study?

Study design: Observational. Population: Unselected patients undergoing CMR (n=60). Intervention: Real-time three-dimensional echocardiography (RT3DE) vs. Cardiovascular magnetic resonance (CMR). Primary outcome: Left ventricular volume indices and ejection fraction (Mean difference: EDV -45 mL, ESV -11 mL, EF -7%, p=<0.001 for EDV and EF, 0.004 for ESV).

November 22, 2011Open Access

Comparison of real-time three-dimensional echocardiography with cardiovascular magnetic resonance for left ventricular volumetric assessment in unselected patients

Q: What are the key findings of this study?

Real-time three-dimensional echocardiography significantly underestimated end-diastolic volume (-45 mL, P<0.001), end-systolic volume (-11 mL, P=0.004), and ejection fraction (-7%, P<0.001) vs CMR.

Key Result

Real-time three-dimensional echocardiography significantly underestimated end-diastolic volume (-45 mL, P<0.001), end-systolic volume (-11 mL, P=0.004), and ejection fraction (-7%, P<0.001) vs CMR.

Study Design

Type

Observational (n=60)

Structured PICO

Does real-time three-dimensional echocardiography accurately measure left ventricular volumes and ejection fraction compared to cardiovascular magnetic resonance in unselected patients?

Population

60 consecutive unselected patients undergoing cardiovascular magnetic resonance (CMR), representative of 'real-world' clinical practice

Intervention

Real-time three-dimensional echocardiography (RT3DE)

Comparator

Cardiovascular magnetic resonance (CMR)

Outcome

Left ventricular (LV) volume indices (end-diastolic volume, end-systolic volume) and ejection fraction (EF)surrogate

In unselected 'real-world' patients, RT3DE substantially underestimates LV volumes and EF compared to CMR, with accuracy heavily dependent on image quality.

Main Result

Effect estimate: Mean difference: EDV -45 mL, ESV -11 mL, EF -7%

p-value: p=<0.001 for EDV and EF, 0.004 for ESV

Limitations

30% of patients had image quality precluding analysis
Suboptimal image quality was associated with higher body mass index and arrhythmia frequency

Abstract

AIMS: To compare left ventricular (LV) volume indices and the ejection fraction (EF) obtained using real-time three-dimensional echocardiography (RT3DE) and cardiovascular magnetic resonance (CMR) in unselected patients representative of 'real-world' clinical practice, and to determine the effect of RT3DE image quality on these parameters. METHODS AND RESULTS: Sixty consecutive patients undergoing CMR underwent same day RT3DE. LV volume and EF measurements were made using both modalities and compared. All scans were independently analysed by a second observer to assess inter-observer variability, and 40% were re-analysed to assess intra-observer variability. RT3DE image quality was graded as good, adequate, and non-analysable. Thirteen (22%) patients had good RT3DE image quality, 29 (48%) had adequate image quality, and 18 (30%) had image quality precluding analysis. Body mass index and arrhythmia frequency were higher in patients with suboptimal image quality. RT3DE significantly underestimated end-diastolic volume (EDV) (-45 ± 35 mL, P < 0.001), end-systolic volume (ESV) (-11 ± 24 mL, P = 0.004), and EF (-7 ± 9%, P < 0.001) compared with CMR although the degree of underestimation was substantially less when image quality was good. Eleven patients (18%) classified as having a normal EF by CMR had a reduced EF according to RT3DE, all but one of which had suboptimal image quality. Observer variability for RT3DE was higher than for CMR for all parameters, however, the difference was not significant when RT3DE image quality was good. CONCLUSIONS: In contrast to previously published data from highly selected patient groups, 'real-world' RT3DE substantially underestimates LV volumes and EF. The degree of underestimation is related to image quality.