Author + information
- Tamara O. Thomas,
- John Jefferies,
- Angela Lorts,
- Jeffrey Anderson,
- Kan Hor,
- Zhiqian Gao and
- Elaine Urbina
An elevated resting heart rate and cardiac failure are frequently observed during the natural history of Duchenne Muscular Dystrophy (DMD). We hypothesize that the elevated resting heart rate reflects autonomic dysfunction that can be identified by heart rate variability (HRV) analyses and this abnormal HRV correlates with abnormal cardiac magnetic resonance imaging (cMR) findings.
DMD patients (N=74) and controls (N=19) had anthropometric and blood pressure data collected with heart rate and HRV analyses via Holter monitoring. Time and frequency domain HRV parameters were calculated. Imaging data was taken from clinical cMR performed on DMD cases only. T-test was used to perform pair-wise comparison between groups. A p-value of <0.05 was used for statistical significance.
DMD cases did not differ from controls in age, height, weight or blood pressure, however, they did differ in body mass index (17.8 + 2.5 years controls, 23 + 6.8 years cases). DMD cases had higher resting average heart rate (83.0 + 9.4 controls, 99.4 + 8.9 cases, p< 0.001). Among HRV variables, decreases were seen in: standard deviation of R to R intervals (p<0.001), the percent RR intervals differing by >50 ms from previous RR interval (p<0.001), the root-mean-square of successive differences of RR intervals (p<0.001), the standard deviation of the mean R to R segment (SDANN, p<0.001), Very Low Frequency (<0.04 Hertz), Low Frequency (0.04-0.15 Hertz) and High Frequency (0.15-0.4 Hertz). Of the HRV variables, SDANN most significantly correlates with positive late gadolinium enhancement on cMR (p 0.01). 19/74 DMD cases were on beta blocker (ββ) and the average resting heart rate differed significantly from those not on ββ (101.5 ± 6.9 no ββ, 93.5 ± yes ββ, p 0.009), however, there was no difference between the groups in HRV analyses. There was no difference in cardiac function by cMR between DMD cases with abnormal versus normal HRV or those on ββ versus not on ββ.
In conclusion, DMD patients have decreased overall HRV which correlates with early scar fibrosis by cMR. This autonomic dysfunction is associated with increased mortality and may be helpful in early risk stratification and medical therapy.
Poster Sessions, Expo North
Saturday, March 09, 2013, 10:00 a.m.-10:45 a.m.
Session Title: Dilated Cardiomyopathies: From Peripartum, Cancer Therapy, Familial Cardiomyopathies to Cardiac Amyloidosis
Abstract Category: 15. Heart Failure: Clinical
Presentation Number: 1134-285
- 2013 American College of Cardiology Foundation