Measurement error in echocardiographic assessment of aortic stenosis: an epidemiological consideration of research methodology and clinical practice

Abstract

Abstract Background/Introduction Current international guidelines on treatment of valvular heart disease contain recommendations for aortic valve replacement based exclusively on abnormal echocardiographic parameters in asymptomatic patients with aortic stenosis (AS). To prevent misclassification and subsequent mistreatment of patients, these recommendations require accurate and unbiased measurements of hemodynamic parameters. Purpose To illustrate consideration and impact of measurement error in echocardiographic assessment of aortic stenosis in both the research and clinical setting. Methods First, a systematic review was performed to investigate the recognition of and correction for measurement error in clinical studies on the prognostic value of peak aortic jet velocity (Vmax), mean pressure gradient (MPG), and effective orifice area (EOA). Second, all potential erroneous sources in the calculation of those primary parameters were listed stratified to random or systematic measurement error, and subsequently their magnitude was quantified. Third, the impact of various types of measurement error on current thresholds for intervention was graphically illustrated in different clinical scenarios. Results The presence of measurement error was acknowledged in 44% of the 36 included studies, while none utilized methods to correct for it. Interobserver variability ranged between 0.9–8.3% for Vmax and MPG but was substantially higher for EOA (range 7.7–12.7%) implying lower reliability (Figure 1). Furthermore, the invalid assumption of a circular left ventricular outflow tract area resulted in a median underestimation in EOA of 22.5% compared to 3D-transesophageal echocardiography (3D-TEE), computed tomography (CT), and cardiovascular magnetic resonance (CMR) planimetry. Figure 2 illustrates the impact of this discrepancy on the classification of AS using one-sided t-tests to determine the areas under the curve; the proportion of patients with non-severe AS in a hypothetical cohort (based on values from the PARTNER 3 trial [1[) increased by 42%. Conclusion(s) Measurement error is underrecognized in studies of echocardiographic assessment of aortic stenosis. This review demonstrates that random and systematic measurement errors affect echocardiographic assessment, leading to potential misdiagnosis and subsequent mistreatment. Clinicians and scientists should be aware of the implications of measurement errors to enhance rightful clinical decision-making and assure research validity. Funding Acknowledgement Type of funding sources: None.