Objectives: As underlying heart diseases of right ventricular tachyarrhythmias, ARVC causes wall-motion abnormalities based on fibrofatty myocardial degeneration, while RVOT-VT and BrS are thought to lack phenotypic MR characteristics. To examine whether cardiac magnetic resonance (CMR) feature tracking (FT) in addition to ARVC objectively facilitates detection of myocardial functional impairments in RVOT-VT and BrS.
Methods: Cine MR datasets of four retrospectively enrolled, age-matched study groups [n = 65; 16 ARVC, 26 RVOT-VT, 9 BrS, 14 healthy volunteers (HV)] were independently assessed by two distinctly experienced investigators regarding myocardial function using CMR-FT. Global strain (%) and strainrate (s-1) in radial and longitudinal orientation were assessed at RVOT as well as for left (LV) and right (RV) ventricle at a basal, medial and apical section with the addition of a biventricular circumferential orientation.
Results: RV longitudinal and radial basal strain (%) in ARVC (- 12.9 ± 4.2; 11.4 ± 5.1) were significantly impaired compared to RVOT-VT (- 18.0 ± 2.5, p ≤ 0.005; 16.4 ± 5.2, p ≤ 0.05). Synergistically, RVOT endocardial radial strain (%) in ARVC (33.8 ± 22.7) was significantly lower (p ≤ 0.05) than in RVOT-VT (54.3 ± 14.5). For differentiation against BrS, RV basal and medial radial strain values (%) (13.3 ± 6.1; 11.8 ± 2.9) were significantly reduced when compared to HV (21.0 ± 6.9, p ≤ 0.05; 20.1 ± 6.6, p ≤ 0.005), even in case of a normal RV ejection fraction (EF) (> 45%; n = 6) (12.0 ± 2.7 vs. 20.1 ± 6.6, p ≤ 0.05).
Conclusions: CMR-FT facilitates relevant differentiation in patients with right ventricular tachyarrhythmias: between ARVC against RVOT-VT and HV as well as between BrS with even a preserved EF against HV.
Keywords: Arrhythmogenic right ventricular cardiomyopathy (ARVC); Brugada syndrome (BrS); Feature tracking (FT); Myocardial strain analysis; Right ventricular outflow tract tachycardia (RVOT-VT).