Introduction:
In managing chronic stable heart failure, accurately assessing left ventricular function is crucial. This assessment often involves measuring left ventricular volumes and ejection fraction (EF). Several techniques are employed for this purpose, including M-mode echocardiography (echo), 2D echo, radionuclide ventriculography, and cardiovascular magnetic resonance (CMR). Understanding whether these techniques yield comparable results is vital for applying findings from large heart failure studies, which often rely on a single measurement method, to broader clinical practice. This study prospectively compares the agreement of left ventricular volumes and EF measurements obtained from these four different techniques in patients with chronic stable heart failure.
Methods and Results:
Fifty-two patients with chronic stable heart failure, participating in the CHRISTMAS Study, underwent M-mode echo, 2D echo, radionuclide ventriculography, and CMR within a four-week period. All scans were analyzed independently and blindly at three core laboratories by a single investigator. Image quality varied across echocardiographic methods; 86% of M-mode echo scans were sufficient for EF measurement using the M-mode method, whereas only 69% of 2D Simpson’s biplane analyses provided adequate images. In contrast, all 52 patients successfully completed and tolerated both radionuclide ventriculography and CMR, and all scans from these modalities were deemed analysable.
The mean left ventricular ejection fraction varied significantly across the techniques. M-mode cube method yielded a mean EF of 39+/-16%, and Teichholz M-mode method resulted in 29+/-15%. 2D echo Simpson’s biplane analysis showed a mean EF of 31+/-10%, radionuclide ventriculography 24+/-9%, and CMR 30+/-11%. Statistical analysis revealed significant differences (P<0.001) between all techniques, except for the comparison between CMR and 2D echo Simpson’s rule (P=0.23).
The Bland-Altman limits of agreement, representing four standard deviations, were widest for CMR versus both cube M-mode echo and Teichholz M-mode echo (66% each). Comparisons between radionuclide ventriculography and cube M-mode echo showed limits of agreement at 58%, CMR versus Simpson’s 2D echo at 44%, and radionuclide ventriculography versus Simpson’s 2D echo at 39%. The narrowest limits of agreement were observed between CMR and radionuclide ventriculography (31%). Similarly, end-diastolic and end-systolic volumes measured by 2D echo and CMR displayed wide limits of agreement (52 ml to 216 ml and 11 ml to 188 ml, respectively).
Conclusion:
The findings of this study indicate that ejection fraction measurements obtained from M-mode echo, 2D echo, radionuclide ventriculography, and CMR are not interchangeable. Consequently, the interpretation of research studies in heart failure should consider the specific measurement techniques utilized. The substantial variances observed in volume and ejection fraction measurements across different techniques, particularly when echocardiography is involved, suggest that CMR may be the superior method for estimating volume and ejection fraction in heart failure patients. This is likely due to CMR’s 3D imaging approach, which better accommodates non-symmetric ventricles, and its generally superior image quality compared to echocardiography and radionuclide ventriculography. These considerations are crucial for clinicians and researchers when assessing left ventricular function and applying research findings in heart failure management.
