Background: Non-ischemic fibrosis (NIF) on cardiac magnetic resonance (CMR) has been linked to poor prognosis, but its association with adverse right ventricular (RV) remodeling is unknown. This study examined a broad cohort of patients with RV dysfunction, so as to identify relationships between NIF and RV remodeling indices, including RV pressure load, volume and wall stress.
Methods and results: The population comprised patients with RV dysfunction (EF<50%) undergoing CMR and transthoracic echo within a 14 day (5 ± 3) interval. Cardiac structure, function, and NIF were assessed on CMR. Pulmonary artery systolic pressure (PASP) was measured on echo. 118 patients with RV dysfunction were studied, among whom 47% had NIF. Patients with NIF had lower RVEF (34 ± 10 vs. 39 ± 9%; p = 0.01) but similar LVEF (40 ± 21 vs. 39 ± 18%; p = 0.7) and LV volumes (p = NS). RV wall stress was higher with NIF (17 ± 7 vs. 12 ± 6 kPa; p < 0.001) corresponding to increased RV end-systolic volume (143 ± 79 vs. 110 ± 36 ml; p = 0.006), myocardial mass (60 ± 21 vs. 53 ± 17 gm; p = 0.04), and PASP (52 ± 18 vs. 41 ± 18 mmHg; p = 0.001). NIF was associated with increased wall stress among subgroups with isolated RV (p = 0.005) and both RV and LV dysfunction (p = 0.003). In multivariable analysis, NIF was independently associated with RV volume (OR = 1.17 per 10 ml, [CI 1.04-1.32]; p = 0.01) and PASP (OR = 1.43 per 10 mmHg, [1.14-1.81]; p = 0.002) but not RV mass (OR = 0.91 per 10 gm, [0.69-1.20]; p = 0.5) [model χ2 = 21; p<0.001]. NIF prevalence was higher in relation to PA pressure and RV dilation and was > 6-fold more common in the highest, vs. the lowest, common tertile of PASP and RV size (p<0.001).
Conclusion: Among wall stress components, NIF was independently associated with RV chamber dilation and afterload, supporting the concept that NIF is linked to adverse RV chamber remodeling.