Abstract Body (Do not enter title and authors here): Background:
Cardiac catheterization along with cardiac biopsy studies have shown the presence of abnormally increased left ventricular (LV) chamber stiffness in patients with severe aortic regurgitation (AR) and its significant correlation with interstitial fibrosis. LV diastolic dysfunction (DD) is associated with increased mortality in several patient populations. However, there is a paucity of data on the association of DD with mortality in patients with AR.

Hypotheses:
1 - LV DD is related to extracellular volume (ECV), imaging marker of interstitial fibrosis, by cardiac magnetic resonance imaging (CMR)
2 - LV DD by echocardiography is associated with mortality in patients with AR

Methods:
We studied patients with moderate or greater AR who underwent echocardiographic and CMR imaging within 12 months. We excluded patients with concomitant valve disease, prior valve intervention, cardiomyopathy deemed unrelated to AR, congenital heart disease and terminal conditions. The primary outcome was all-cause death. CMR was used to obtain LV volumes, EF and mass, AR severity, scar extent by delayed hyperenhancement, and ECV. DD was assessed by comprehensive echocardiography.

Results:
The study included 323 patients. Mean age was 61.9 ± 16.0 years and 22% were female. Median follow-up was 3.8 years, during which 65 patients died and 172 had aortic valve replacement. Median LV EF was 56 (47-65) %, AR volume on CMR was 40 (30-61) mL, and AR fraction was 40 (33-47) %. ECV progressively increased with higher grades of LV DD (Figure 1).
Table 1 shows the univariate associations with mortality in the study. On multivariable analysis based on the Lasso variable selection process, Euroscore, Charlson comorbidity index, DD grade, and RAP were associated with total mortality.

Conclusion:
ECV by CMR progressively increases with higher grades of DD by echocardiography, and DD is independently associated with mortality in patients with AR.