Relationship between native papillary muscle T1 time and severity of functional mitral regurgitation in patients with non-ischemic dilated cardiomyopathy

Background: functional mitral regurgitation is one of the severe complications of non-ischemic dilated cardiomyopathy (dcm). non-contrast native t1 mapping has emerged as a non-invasive method to evaluate myocardial fibrosis. we sought to evaluate the potential relationship between papillary muscle t1 time and mitral regurgitation in dcm patients. methods: forty dcm patients (55 ± 13 years) and 20 healthy adult control subjects (54 ± 13 years) were studied. native t1 mapping was performed using a slice interleaved t1 mapping sequence (stone) which enables acquisition of 5 slices in the short-axis plane within a 90 s free-breathing scan. we measured papillary muscle diameter,length and shortening. dcm patients were allocated into 2 groups based on the presence or absence of functional mitral regurgitation. results: papillary muscle t1 time was significantly elevated in dcm patients with mitral regurgitation (n = 22) in comparison to those without mitral regurgitation (n = 18) (anterior papillary muscle: 1127 ± 36 msec vs 1063 ± 16 msec,p < 0.05; posterior papillary muscle: 1124 ± 30 msec vs 1062 ± 19 msec,p < 0.05),but lv t1 time was similar (1129 ± 38 msec vs 1134 ± 58 msec,p = 0.93). multivariate linear regression analysis showed that papillary muscle native t1 time (β = 0.10,95 % ci: 0.05-0.17,p < 0.05) is significantly correlated with mitral regurgitant fraction. elevated papillary muscle t1 time was associated with larger diameter,longer length and decreased papillary muscle shortening (all p values <0.05). conclusions: in dcm,papillary muscle native t1 time is significantly elevated and related to mitral regurgitant fraction. © 2016 the author(s).