Arrhythmic Risk Prediction in ARVC | 173 Table 2 . Associations between deformation parameters and first sustained VA HR (95% CI) p-value LV GLS 1.20 (1.10 – 1.31) <0.001 per % worsening LVMD (ln) 2.73 (1.07 – 6.98) 0.036 per ln(ms) increase RVFWLS 1.12 (1.08 – 1.17) <0.001 per % worsening RVMD (ln) 3.09 (1.73 – 5.53) <0.001 per ln(ms) increase RV deformation pattern 10.94 (2.63 – 45.56) <0.001 when abnormal Hazard ratios (HR) are presented with 95% CIs. Since linearity and proportional hazards assumption testing criteria showed signs of non-linearity for mechanical dispersion, the timing variables LVMD and RVMD were subjected to log-transformation. Abbreviations: GLS = global longitudinal strain, LV = left ventricular, MD = mechanical dispersion, RV = right ventricular, RVFWLS = right ventricular free wall longitudinal strain, VA = ventricular arrhythmia. Table 3. The added value of deformation imaging for personalized arrhythmic risk prediction in ARVC Adjusted HR (95% CI) p-value C-statistic (95% CI) AIC Risk calculator model … … 0.78 (0.71 – 0.86) 299.2 + RVFWLS per % worsening 1.07 (1.02 – 1.11) 0.004 0.82 (0.75 – 0.88) -7.2 + RV deformation abnormal 4.45 (1.07 – 18.57) 0.040 0.82 (0.75 – 0.88) -6.6 + LV GLS per % worsening 1.07 (0.98 – 1.18) 0.138 0.79 (0.72 – 0.86) -1.3 Hazard ratios (HR) are adjusted for the calculator-predicted risk. HR and optimism corrected C-statistic are presented with 95% CIs. Abbreviations: AIC = Akaike information criterion, ARVC = arrhythmogenic right ventricular cardiomyopathy, LV GLS = left ventricular global longitudinal strain, RV = right ventricular, RVFWLS = right ventricular free wall longitudinal strain. DISCUSSION In this study, we showed that echocardiographic deformation imaging can further refine personalized arrhythmic risk prediction when added to the ARVC risk calculator. Both abnormal regional RV deformation patterns and RVFWLS as a continuous indicator of RV function showed independent predictive value on top of the risk calculator and improved its discriminative value. Measures of LV deformation, on the other hand, did not add predictive value in this cohort. Importantly, all patients who experienced VA within 5 years from the echocardiographic assessment showed abnormal RV deformation patterns at baseline. Risk stratification in patients with ARVC Arrhythmic risk prediction is a central part of clinical management of ARVC patients, in order to determine if and when an ICD is warranted. Especially in this disease, risk prediction is challenging, since life-threatening arrhythmias can already occur early in the disease.2 Predictors of unfavourable outcome which were identified over the past decades were recently summarized in a meta-analysis24 and subsequently used for the development of a 8
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