The heart in muscular dystrophies

Identification of Cardiomyopathy-Associated Circulating miRNA Biomarkers in Muscular Dystrophy Female Carriers Using a Complementary Cardiac Imaging and Plasma Profiling Approach

Background: Different from males with Duchenne/Becker muscular dystrophy (DMD/BMD) in whom overt myopathy is the rule, muscular dystrophy (MD) female carriers are mostly free of skeletal muscle symptoms. However, similar to MD males, these females are also prone to cardiomyopathy. Since circulating microRNAs (miRNAs) have been proposed as diagnostic biomarkers for various cardiovascular diseases, the aim of the current study was to identify specific circulating miRNAs in the plasma of female DMD/BMD carriers that may allow an early and accurate diagnosis of cardiac involvement in these cases.

Methods: Twenty-nine female MD carriers and 24 age-matched healthy female controls were prospectively enrolled. All MD carriers and controls underwent comprehensive cardiovascular magnetic resonance (CMR) studies as well as venous blood sampling on the same day.

Results: An impaired left ventricular (LV) systolic function was detected in 4 (14%) MD carriers while late gadolinium enhancement (LGE) indicative of myocardial fibrosis was present in 13 female patients (45%)—with an exclusively non-ischemic pattern. Among the circulating miRNAs examined, six were significantly up-regulated in MD carriers compared to female controls: miR-206 (103-fold increase, p < 0.0001), miR-222 (41-fold, p < 0.0001), miR-26a (fourfold, p = 0.029), miR-342 (27-fold, p < 0.0001), miR-378a-3p (minimum 3,600-fold; almost undetectable in controls, p = 0.013), miR-378a-5p (64-fold, p < 0.0001); only two miRNAs were substantially down-regulated in MD carriers: miR-144 (p < 0.0001) and miR-29a (p = 0.002) (both undetectable in carriers). A significant down-regulation of the miR-29c (<0.001-fold, p = 0.006) was observed in MD carriers with abnormal CMR findings (comprising functional and/or structural abnormalities) compared to those with normal CMR examinations. Univariable analyses regarding the presence of abnormal CMR findings resulted in four significant variables: LV end-diastolic volume index (EDVi), LV end-systolic volume index (ESVi), an elevated plasma creatine kinase (CK), and decreased serum miR-29c levels. In subsequent multivariable analysis, the only independent predictor for an abnormal CMR among MD carriers was circulating miR-29c (OR 0.99, 95% CI 0.98–0.99, p = 0.037). Moreover, an elevated CK and/or a downregulated miR-29c level (<0.05 × 10^-3) resulted in an improved AUC value of 0.79 (0.62–0.97, p = 0.007) (79, 80 and 80%, sensitivity, specificity and overall accuracy) for the CMR-based diagnosis of cardiomyopathy in MD carriers when compared to using the two parameters individually.

Conclusion: In female MD carriers, down-regulation of circulating miR-29c relates to the presence of functional and/or structural cardiac abnormalities (as detected by CMR) and appears to be a promising novel biomarker—in addition to conventional CK plasma levels—for an early diagnosis of cardiomyopathy.

Identification of cardiomyopathy associated circulating miRNA biomarkers in patients with muscular dystrophy using a complementary cardiovascular magnetic resonance and plasma profiling approach

BACKGROUND

Duchenne and Becker muscular dystrophy (DMD and BMD) are X-chromosomal recessive neuromuscular disorders that are caused by mutations in the dystrophin gene and characterized by cardiac involvement. Circulating microRNAs (miRNAs) have been proposed as diagnostic biomarkers for various cardiovascular diseases. However, circulating miRNAs reflecting the presence and/or disease severity of cardiac involvement in DMD/BMD patients have not been described so far.

METHODS

Sixty-three male patients with known MD and 26 age-matched healthy male controls were prospectively enrolled. All MD patients and controls underwent comprehensive cardiovascular magnetic resonance (CMR) studies as well as venous blood sampling on the same day.

RESULTS

An impaired left ventricular (LV) systolic function (defined as LV-EF <55 %) was detected in 29 (46 %) and presence of late gadolinium enhancement (LGE) indicative of myocardial fibrosis in 48 (76 %) MD patients with an exclusively non-ischemic pattern. Whereas no significant differences were observed for the 27 selected circulating miRNAs in MD patients with abnormal CMR findings (comprising structural and/or functional impairments) compared to those with completely normal CMR studies, a significant up-regulation of three miRNAs was observed in LGE-positive MD patients compared to LGE-negative ones: miR-222 (1.8-fold, p = 0.035), miR-26a (2.1-fold, p = 0.03) and miR-378a-5p (2.4-fold, p = 0.026). A signature of these three miRNAs (miR-26a, miR-222 and miR-378a-5p) resulted in an area under the curve (AUC) value of 0.74 for the diagnosis of LGE-positive MD patients. In a multivariable model, three independent predictors for LGE presence were identified comprising not only clinical and laboratory markers (LV-EF: OR 0.47, 95 % CI 0.24-0.89, p = 0.021 and elevated hs-Trop: OR 2559, 95 % CI 2.97-22.04*10(5), p = 0.023) but also the circulating miR-222 (OR 938, 95 % CI 938.46, 3.56-24.73*10(4), p = 0.016).

CONCLUSIONS

Up-regulation of circulating miRNAs miR-222, miR-26a and miR-378a-5p indicates the presence of myocardial scars in MD patients. Plasma miR-222 appears to be a promising novel biomarker reflecting structural - but not functional - cardiac alterations in MD patients.

Left ventricular systolic function and the pattern of late-gadolinium-enhancement independently and additively predict adverse cardiac events in muscular dystrophy patients

BACKGROUND

Cardiac involvement is a frequent finding in patients with Duchenne (DMD) and Becker (BMD) muscular dystrophies. With this study, we aimed at elucidating the relationship between the phenotypic expression of cardiac involvement and the occurrence of adverse cardiac events in DMD/BMD patients.

METHODS

Eighty-eight male DMD/BMD patients (age 29 ± 14 yrs) were prospectively enrolled. All patients underwent cardiovascular magnetic resonance (CMR) comprising cine- and late-gadolinium-enhancement (LGE)-CMR at study entry and were subsequently followed-up for adverse cardiac events. The primary endpoint was defined as all-cause/cardiac death or cardiac transplantation. Secondary endpoints were (1) hospitalization for heart failure and/or (2) occurrence of non-/sustained ventricular tachycardia (VT).

RESULTS

During a mean follow-up time of 47 ± 18 months, the primary endpoint was observed in three (3%) and the secondary endpoint in 21 (24%) patients. On multivariable analysis, LV-EF (HR, 95% CI: 0.94, 0.89-0.97, p = 0.001) and the presence of "transmural" LGE (HR, 95% CI: 2.89, 1.09-7.68, p = 0.033) were the only independent predictors for secondary endpoints. A cut-off for LV-EF of 45% was associated with the highest hazard ratio (HR, 95% CI: 11.50, 4.49-29.43, p < 0.0001) in a Cox regression survival analysis. In the group of patients with a LV-EF (>45%), those patients already showing "transmural" LGE had a significantly lower event-free-survival (HR, 95% CI: 13.48, 1.89-96.12, p = 0.009) compared to those without.

CONCLUSIONS

An impaired LV systolic function (LV-EF ≤45%) and a "transmural" pattern of myocardial fibrosis independently predict the occurrence of adverse cardiac events in DMD/BMD patients. Even in DMD/BMD patients with relatively preserved LV-EF (>45%), the simple and visually assessable parameter "transmural LGE" is of additive prognostic value.