Two types of myocardial fibrosis, specifically localized replacement fibrosis, which may be seen with late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR), and diffuse interstitial fibrosis, are associated with left ventricular (LV) remodeling caused by chronic aortic regurgitation (AR) causes that can be interpreted using T1 mapping methods. The current study used CMR to evaluate LV remodeling for the identification of both forms of myocardial fibrosis and assess the correlation with clinical outcomes.
Patients undergoing CMR and valve assessment through T1 mapping diagnosed with chronic AR from 2011 to 2018 were included in the study. Myocardial fibrosis patients having a complicated etiology were eliminated. LGE and pre-and post-contrast of T1 mapping were used to assess extracellular volume (ECV) and indexed ECV (iECV) in addition to enumerating LV volumetrics and AR severity. Follow-up was done to see if the patients needed an aortic valve replacement and to evaluate composite event of death.
Overall, 177 patients diagnosed with isolated chronic AR were enrolled in the study, where 66% were males with a median age- 58 years (47.0 years-68.0 years), and median follow-up was 2.5 years (1.07 years-3.56 years). A substantial increase in iECV with AR severity (P < 0.001) was observed, while replacement fibrosis and ECV did not increase (P = NS). Moreover, the iECV link continued with the composite event on multivariate analysis (P = 0.01). Also, increased event rates were seen in patients with iECV ≥24 mL/m2 and AR RF severity ≥30% on Kaplan-Meier analysis stratified by iECV and AR regurgitant fraction (RF).
Compared to ECV or replacement fibrosis, iECV has a strong connection with survival without aortic valve replacement among cardiac magnetic resonance biomarkers.