Variability of left ventricular volume and ejection fraction measurements using contrast echocardiography: The influence of the left ventricular length measurements in a large cohort of patients during monitoring cardiotoxic effects of chemotherapy

OBJECTIVE: To investigate the influence of length difference in left ventricular (LV) long axis between the apical four-chamber and two-chamber views on measurements of LV volumes and ejection fraction (EF). METHODS: Seven hundred consecutive cancer patients underwent contrast echocardiography from July 2010 to May 2014. All patients received the echocardiographic contrast agent Definity. Recordings of apical views were analyzed by a sonographer and then by a cardiologist. The end-diastolic and end-systolic LV volumes (EDV and ESV), and LV lengths as well as EF, were measured using the biplane Simpson's method. Inter-observer variability was assessed using relative mean error (RME) and Bland-Altman analysis. RESULTS: Six hundred ninety-two patients had contrast echocardiograms with complete endocardial definition. The LV length difference of the long axis measured by the cardiologist was ≤1 mm in 284 studies (41%), 2 mm in 146 studies (21%), 3 mm in 103 studies (15%), and ≥4 mm in 159 studies (23%). The limits of agreement (LOA) and RME increase with the increasing length difference. Compared to the groups with length difference <4 mm, the RME of the measurements of indexed EDV, indexed ESV, and EF was significantly greater in the group with length difference ≥4 mm (P < .05). CONCLUSION: These results highlight the need for reviewing the LV long axis length measurements in order to provide reproducible LV volumes and EF measurements and may be used as benchmarks for quality control. A length difference of ≤3 mm can be achieved in most of our patients and is associated with an excellent inter-observer agreement.