28 | Chapter 2 RESULTS Of 59 patients (age 38 ± 17 years, 49% male), the experts diagnosed 15 (25%) with ARVC. Conventional echocardiographic TFC, either minor or major, were observed in 10 (67%) patients. Using deformation imaging instead of visual wall motion assessment led to 5 (33%) additional detections of ARVC, whereas none were reclassified to normal. Consequently, deformation imaging increased sensitivity from 67% to 100%, while specificity decreased from 89% to 73%. The C-statistic increased from 0.78, 95%CI (0.64-0.91) to 0.86, 95%CI (0.80-0.93). (Figure 1B) Of note, half (n=6/12) of the patients with “false positive” abnormal deformation patterns were at risk family members of ARVC patients. They all developed new TFC during follow-up and 4 of them later fulfilled criteria for a definite diagnosis. Therefore, it can be debated whether the deformation abnormalities in these patients were truly “false positive” or, more likely, reflective of a very early sign of disease in these patients.3 Deformation imaging detected all patients who developed the diagnosis during follow-up, and including these patients resulted in an increased specificity (80%) and C-statistic (0.74, 95%CI [0.62-0.86] to 0.90, 95%CI [0.84-0.96]). DISCUSSION AND CONCLUSION We showed that RV deformation is highly sensitive for diagnosing ARVC, and improves the diagnostic performance of echocardiographic TFC when replacing the visual wall motion assessment. When the original 1994 TFC were revised in 2010, hypokinesia was disregarded as a criterion and only akinesia/dyskinesia remained.1 This was necessary to prevent overdiagnosing of the disease, but consequently led to a loss in sensitivity. As wall motion abnormalities are a prerequisite to fulfil a criterion, the diagnostic performance of echocardiography depends primarily on visual assessment of RV wall motion abnormalities, which is difficult and highly dependent on the observer’s experience. Replacing visual assessment by deformation imaging offers a solution for this loss in sensitivity, while also being less subjective. In the present study, all patients who were diagnosed with ARVC by the expert panel were detected by RV deformation abnormalities. The cohort size and absence of a true gold standard test for ARVC were limitations in our study design. Because deformation imaging is not able to reliably distinguish ARVC from other RV related disease as a stand-alone index, such diagnostic dilemmas should always be conducted in a clinical multi-modality approach like the TFC. Using deformation imaging instead of visual wall motion assessment improved the overall performance of echocardiographic TFC for diagnosing ARVC. Acknowledgements: This work was supported by the Netherlands Cardiovascular Research Initiative, an initiative with support of the Dutch Heart Foundation (grant number CVON2015-12 eDETECT). Dr Te Riele is supported by the Dutch Heart Foundation (grant number 2015T058) and the UMC Utrecht Fellowship Clinical Research Talent. Dr Asselbergs is supported by UCL Hospitals NIHR Biomedical Research Centre.
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