Abstract 13041: Assessment of Cardiac Involvement in Myotonic Muscular Dystrophy Patients Using T1 Mapping MRI.
Background: Patients with myotonic dystrophy (DM) are at risk for conduction block and left ventricular dysfunction. Non-invasive detection of diffuse myocardial fibrosis may improve the risk prediction of sudden death in this population.
Methods: Thirty-three patients with DM (24 with type 1 and 9 with type 2) underwent cardiac magnetic resonance (CMR) for assessment of left ventricular indices and evaluation of diffuse myocardial fibrosis by T1 mapping. Comparisons were made to a control group of 13 healthy volunteers. The association of average myocardial T1 time with LV indices, CTG repeat size, standard and signal-averaged ECG findings were evaluated using regression models.
Results: The mean age of DM patients and control subjects were 46 and 38 years, respectively (P>0.05). 46 % of DM patients and 54% of controls were men. Compared to control subjects, DM patients had lower end-diastolic volume index (68.9 ± 9.7 vs. 60.3 ± 17.6 ml/m2, p=0.045) and cardiac index (2.7 ± 0.3 vs. 2.33 ± 0.6 L/min/m², p=0.005). Post contrast myocardial T1 time was significantly shorter in DM patients compared to controls (figure, p<0.0001). Among DM patients, there was a positive association between higher T1 time and LV mass index (2.2 ms longer per g/m2, p=0.006), LV end-diastolic volume index (1.3 ms longer per ml/m2, p=0.026), filtered QRS duration (1.2 ms longer per unit, p=0.005) and low-amplitude (<40micro-V) late-potential duration (0.9 ms longer per unit, p=0.01). After adjusting for age, CTG count, and gender in multivariate random effects regression models, each 10 ms increase in myocardial T1 time of type 1 patients was independently associated with 1.3 ms increase in longitudinal PR and QRS intervals during follow-up.
Conclusions: DM is associated with structural alterations on CMR. Post-contrast myocardial T1 time was shorter in DM patients than controls likely reflecting the presence of diffuse myocardial fibrosis.
- © 2011 by American Heart Association, Inc.