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

Résumé

Background Functional mitral regurgitation is one of the severe complications of non-ischemic dilated cardiomyopathy (DCM). Non-contrast native T 1 mapping has emerged as a non-invasive method to evaluate myocardial fibrosis . We sought to evaluate the potential relationship between papillary muscle T 1 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 T 1 mapping was performed using a slice interleaved T 1 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 T 1 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 T 1 time was similar (1129 ± 38 msec vs 1134 ± 58 msec, p = 0.93). Multivariate linear regression analysis showed that papillary muscle native T 1 time (β = 0.10, 95 % CI: 0.05–0.17, p < 0.05) is significantly correlated with mitral regurgitant fraction . Elevated papillary muscle T 1 time was associated with larger diameter, longer length and decreased papillary muscle shortening (all p values <0.05). Conclusions In DCM, papillary muscle native T 1 time is significantly elevated and related to mitral regurgitant fraction.

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