Patients with Isolated Focal Right Ventricular Dyskinetic Segments: Toward a Better Understanding of This Cohort.

Background: The 2010 revised Task Force criteria for the diagnosis of arrhythmogenic right ventricular cardiomyopathy (ARVC) provided guidance for the classification of patients as definitive, borderline or possible ARVC. However, many patients with clinical suspicion for ARVC have isolated RV dyskinetic segments only and partly meet cardiac magnetic resonance (CMR) imaging criteria. This subgroup of patients and the implication of this imaging finding remain not well defined.

Methods: There were 65 consecutive patients with clinical suspicion for ARVC who were referred for CMR between 2015 and 2017. The presence of fatty infiltration and fibrosis were assessed using T2 imaging and myocardial delayed enhancement sequences, respectively. RV wall motions, volumes and ejection fraction (EF) of all patients were re-analysed and quantified. Available data on family history, Holter findings, and electrocardiograms were also reviewed.

Results: There were 5 patients (7.7%) that fulfilled major CMR criteria for ARVC: 4 were classified as having definitive ARVC; and 1/5 as borderline. There were 33 patients with no RV dyskinetic segments: none were classified as having definitive or borderline ARVC; 4/33 were classified as possible ARVC, leaving 29/33 as normal or no ARVC. Finally, there were 27 remaining patients (41.5%) with isolated RV dyskinetic segments: 1/27 was classified as definitive ARVC; 4/27 as borderline; 8/27 as possible; leaving 15/27 as indeterminate. Compared to control, those with isolated RV dyskinesia (including the subgroup labelled as indeterminate 15/27) had more abnormal RVEF, larger RV end-diastolic volume index (82 ± 12 mL/m² vs. 72 ± 12 mL/m², p-value 0.0127), and a trend for higher odds of dilated RV (odds ratio 3.0 [0.81-11], p-value 0.09).

Conclusions: Among patients with a clinical suspicion for ARVC, almost 40% had isolated focal RV dyskinetic segments with the majority remaining unclassified. This cohort had more RV dilation and abnormal EF compared to control.