Prevalence of structural cardiac abnormalities in patients with myotonic dystrophy type I.
BACKGROUND
Myotonic dystrophy type 1 (DM1) is a neurological disorder with known cardiac involvement, including conduction disturbances, arrhythmias, and ventricular dysfunction. We studied which clinical and electrocardiographic features are associated with structural cardiac abnormalities.


METHODS
History, physical examination, electrocardiography, and genetic testing were performed on 382 patients with DM1, and cardiac imaging was performed on 100 of these patients.


RESULTS
Clinical congestive heart failure was found in 7 of the 382 patients (1.8%). Structural cardiac abnormalities determined with cardiac imaging included left ventricular hypertrophy (19.8%), left ventricular dilatation (18.6%), left ventricular systolic dysfunction (14.0%), mitral valve prolapse (13.7%), regional wall motion abnormality (11.2%), and left atrial dilatation (6.3%). Left ventricular systolic dysfunction was associated with increasing age (relative risk [RR], 1.9 per decade; 95% CI, 1.1-3.2; P =.02), cytosine-thymine-guanine (CTG) repeat length (RR, 2.8 per 500 repeats; 95% CI, 1.3-6.3; P =.01), P-R >200 ms (RR, 14.7; 95% CI, 3.0-73.1; P =.001), and QRS >120 ms (RR, 5.7; 95% CI, 1.5-21.8; P =.01). P-R >200 ms was predictive of regional wall motion abnormalities. QRS >120 ms correlated with regional wall motion abnormalities and left atrial dilatation.


CONCLUSIONS
Several clinical and electrocardiographic findings in patients with DM1 are significantly associated with structural heart abnormalities. These results suggest an underlying genetic and pathophysiologic correlate that may lead to cardiac disease in these patients.
Bhakta
Deepak
D
Department of Medicine, Krannert Institute of Cardiology, Indiana University, Indianapolis, Ind 46202, USA. dbhakta@iupui.edu
Lowe
Miriam R
MR
Groh
William J
WJ
D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D006331:Heart Diseases / Q000150:complications* / Q000453:epidemiology / Q000235:genetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D009223:Myotonic Dystrophy / Q000150:complications* / Q000235:genetics; D015995:Prevalence