Boys With Duchenne Muscular Dystrophy Have Diastolic Dysfunction Based on CMR

Abstract

Background: Cardiomyopathy is the leading cause of death in boys with Duchenne muscular dystrophy (DMD). While cardiac magnetic resonance (CMR) is routinely used to assess fibrosis and left ventricular (LV) ejection fraction, CMR measures of LV filling and ejection in DMD have not been reported.

Methods: Patients with DMD (n=179) and healthy controls (n=96) were prospectively enrolled and underwent CMR. The DMD cohort was followed clinically at multiple institutions, and clinical data were recorded. Standard volumes and functions were calculated, and LV filling and ejection curves were measured from baseline CMR. Multivariable linear regressions were used to compare ventricular filling and ejection measures between groups, adjusting for baseline differences. Cox regressions were used to evaluate the relationship between diastolic function measures and mortality in the DMD cohort.

Results: Patients with DMD had significantly smaller stature and ventricular volumes than healthy control patients (P<0.001). They had lower baseline LV ejection fraction (P<0.001), though most had normal systolic function. When adjusted for age, sex, heart rate, body surface area, and LV end-diastolic volume, patients with DMD had slower peak filling rates (P<0.001) and peak ejection rates (P<0.001), as well as slower time to peak ventricular ejection rate (P=0.011). When adjusted for heart rate, a lower peak ventricular ejection rate (P=0.007) and peak filling rate (P=0.033), normalized to LV end-diastolic volume, were associated with mortality in patients with DMD.

Conclusions: Patients with DMD have significantly different baseline CMR filling and ejection indices compared with controls. Some filling indices are associated with mortality and may be useful prognostic measures. Further research is needed in larger cohorts to determine the prognostic value of these differences.

Keywords: cardiomyopathies; diastole; magnetic resonance imaging; muscular dystrophies; prognosis.

Figure 1.. Sample Left Ventricular Filling Curves.

PER represents the most negative slope in systole, and PFR represents the most positive slope in diastole. tPER is the time from end-diastole to PER, and tPFR is the time from end-systole to PFR. (A) shows a normal left ventricular filling curve. Compared with (B), which shows an abnormal filling curve, (A) has higher PER and PFR and shorter tPER and tPFR. PER = peak ejection rate, PFR = peak filling rate, tPER = time to peak ejection rate, tPFR = time to peak filling rate.