Increased plasma concentration of atrial natriuretic hormone in myotonic dystrophy.

Atrial natriuretic hormone (ANH) concentrations were measured in 16 patients affected with myotonic dystrophy (MyD) undergoing 24-hour Holter ECG and in 15 age-matched normal subjects. Although the MyD patients did not show overt left ventricular function impairment, their plasma ANH levels were found to be higher (183.76 +/- 113.25 pg/ml) compared to those of the control subjects (39.73 +/- 9.95 pg/ml, p < 0.001). Nine patients with arrhythmias and some echocardiographic alterations formed subgroup A. Seven patients without cardiac alterations formed subgroup B. No significant difference in ANH emerged between the two subgroups. This evidence suggests that high plasma ANH levels in MyD cannot always be related to overt or latent heart failure and to arrhythmias.