32 | Chapter 3 ABSTRACT Objectives In this study, we aimed to perform an external validation of the value of RV deformation patterns and RV mechanical dispersion in patients with arrhythmogenic cardiomyopathy (AC). Secondly, we assessed the association of these parameters with life threatening ventricular arrhythmia (VA). Background Subtle RV dysfunction assessed by echocardiographic deformation imaging is valuable in AC diagnosis and risk prediction. Two different methods have emerged, the RV deformation pattern recognition and RV mechanical dispersion, but these have neither been externally validated nor compared. Methods We analysed AC probands and mutation-positive family members, matched from two large European referral centers. We performed speckle tracking echocardiography, whereby we classified the subtricuspid deformation patterns from normal to abnormal and assessed RV mechanical dispersion from 6 segments. We defined VA as sustained ventricular tachycardia, appropriate ICD therapy, or aborted cardiac arrest. Results We included 160 subjects, 80 from each center (43% proband, 55% female, aged 41 ± 17 years). VA had occurred in 47 (29%) subjects. In both cohorts, patients with a history of VA showed abnormal deformation patterns (96% and 100%) and had greater RV mechanical dispersion (53 ± 30 ms vs. 30 ± 21 ms, p <0.001 for the total cohort). Both parameters were independently associated to VA (adjusted OR 2.71, 95% CI (1.47 – 5.00) per class step-up and 1.26, 95% CI (1.07 – 1.49) per 10 ms, respectively). The association with VA significantly improved when adding RV mechanical dispersion to pattern recognition (NRI 0.42, p = 0.02 and IDI 0.06, p = 0.01). Conclusion We externally validated two RV dysfunction parameters in AC. Adding RV mechanical dispersion to RV deformation patterns significantly improved the association with life-threatening VA, indicating incremental value.
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