Ventricular late potentials in myotonic dystrophy.
OBJECTIVE
To determine the prevalence of ventricular late potentials, as determined by signal-averaged electrocardiography, in patients with myotonic dystrophy.


METHODS
Cross sectional, with blinded analysis of all electrocardiographic data.


METHODS
Outpatient departments of a Veterans Affairs medical center and a tertiary care private hospital.


METHODS
Twenty-four patients with myotonic dystrophy. Patients were excluded from the study if they had either a history suggestive of significant ventricular arrhythmias or electrocardiographic evidence of a bundle-branch block. Two comparison groups were also formed; one group included 44 healthy employees at the tertiary hospital and the other, 30 cardiac patients with inducible ventricular tachycardia.


RESULTS
A time-domain analysis of the signal-averaged electrocardiograms showed that 75% of patients with myotonic dystrophy met one criterion for the presence of late potentials, 67% met two criteria, and 29% met all three criteria. Spectrotemporal mapping in these patients showed markedly abnormal spectral peaks with a mean factor of normality that was significantly lower than that of the normal volunteers; the frequency of electrocardiographic abnormalities approached that seen in patients with known ventricular tachycardia. The presence of late potentials correlated directly with the length of the PR interval and inversely with left ventricular fractional shortening.


CONCLUSIONS
In our study, the prevalence of late potentials on signal-averaged electrocardiography in patients with myotonic dystrophy approached that seen in cardiac patients with inducible ventricular tachycardia. It is possible that ventricular arrhythmias play a role in the occurrence of sudden death in some patients with myotonic dystrophy.
Milner
M R
MR
Veterans Affairs Medical Center, Washington, DC.
Hawley
R J
RJ
Jachim
M
M
Lindsay
J
J
Fletcher
R D
RD
D000328:Adult; D003430:Cross-Sectional Studies; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006352:Heart Ventricles / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009223:Myotonic Dystrophy / Q000503:physiopathology*; D012815:Signal Processing, Computer-Assisted; D013223:Statistics as Topic