Echocardiography Core Laboratory Reproducibility of Cardiac Safety Assessments in Cardio-Oncology

As the potential for cancer therapy-related cardiac dysfunction is increasingly recognized, there is a need for the standardization of echocardiographic measurements and cut points to guide treatment. The aim of this study was to determine the reproducibility of cardiac safety assessments across two academic echocardiography core laboratories (ECLs) at the University of Pennsylvania and the Duke Clinical Research Institute.

To harmonize the application of guideline-recommended measurement conventions, the ECLs conducted multiple training sessions to align measurement practices for traditional and emerging assessments of left ventricular (LV) function. Subsequently, 25 echocardiograms taken from patients with breast cancer treated with doxorubicin with or without trastuzumab were independently analyzed by each laboratory. Agreement was determined by the proportion (coverage probability [CP]) of all pairwise comparisons between readers that were within a prespecified minimum acceptable difference. Persistent differences in measurement techniques between laboratories triggered retraining and reassessment of reproducibility.

There was robust reproducibility within each ECL but differences between ECLs on calculated LV ejection fraction and mitral inflow velocities (all CPs < 0.80); four-chamber global longitudinal strain bordered acceptable reproducibility (CP = 0.805). Calculated LV ejection fraction and four-chamber global longitudinal strain were sensitive to small but systematic interlaboratory differences in endocardial border definition that influenced measured LV volumes and the speckle-tracking region of interest, respectively. On repeat analyses, reproducibility for mitral velocities (CP = 0.940-0.990) was improved after incorporating multiple-beat measurements and homogeneous image selection. Reproducibility for four-chamber global longitudinal strain was unchanged after efforts to develop consensus between ECLs on endocardial border determinations were limited primarily by a lack of established reference standards.

High-quality quantitative echocardiographic research is feasible but requires a commitment to reproducibility, adherence to guideline recommendations, and the time, care, and attention to detail to establish agreement on measurement conventions. These findings have important implications for research design and clinical care.