Electrocardiographic findings in myotonic dystrophy.

The Natural Course of Cardiac Conduction Disturbances in Myotonic Dystrophy

“…It is worthy of note that intermit tent first-degree atrioventricular block be came stable in 3/5 of our patients; although intermittent first-degree atrioventricular block in itself cannot be considered a patho logical finding in a general population, it must be regarded with caution in patients with MD as it might represent an early sign of developing more advanced conduction disorders. As reported by others [3,4], ab normal Q waves were found in those subjects with the moderate to severe forms of the neuromuscular disorder; in our series this pattern occurred in association with progres sive worsening of the conducting system le sions. The clinical and prognostic implica tions of pathological Q waves remain to be investigated.…”

“…Cardiac involvement in myotonic dystro phy (MD) includes a selective derangement of the specialized system rather than myo cardium [ 1,2]; the resulting rhythm and con duction disturbances may show various de grees of severity [3][4][5] and may be lifethreatening [6][7][8], However, the progressive deterioration of the disorders of conducting tissue has been documented in a limited number of patients [9][10][11][12][13][14][15]. In this study we describe the clinical characteristics and car diac outcome of a group of patients with MD at a mean interval of 46 months.…”

24-Hour Electrocardiographic Study in Myotonic Dystrophy

“…These two hospitals serve a region in the coastal area of Norrbotten, the northernmost county in Swe den, where there is an extremely high prevalence of myotonic dystrophy [6]. The diagnosis of myotonic dystrophy was based on clinical neuromuscular inves tigation and confirmatory electromyography when the clinical findings were not unequivocal.…”

“…This may be a reflection of the paucity of ambulatory electrocardiographic studies. We have, in a recent study with conventional resting electrocardiography, shown that the prevalence and severity of electrocardiographic abnormalities in myo tonic dystrophy are closely related to the severity of the neuromuscular disease [6]. The relation of transient electrocardiograph ic abnormalities to the severity of the neuro muscular symptoms has, however, pre viously not been studied.…”

“…Other have only cat aracts or an individual symptom complex such as cardiac involvement or dysphagia [2], Experimental and clinical data suggest that myotonic dystrophy represents a geneti cally induced primary alteration in the struc ture and function of cellular membranes, but the specific metabolic defect has not been defined [3]. It has recently been proposed that myotonic dystrophy may represent not one isolated entity but a class of genetic defects having similar expression [4], Electrocardiographic evidence of cardiac involvement occurs in a majority of patients with myotonic dystrophy and includes atrioventricular and intraventricular con duction defects, and a variety of arrhythmias [5][6][7][8][9]. Although several authors have re ported that patients with this disease are at risk of having malignant ventricular arrythmias, complete atrioventricular block, and sudden unexpected death [10,11], the infor mation concerning the clinical significance of electrocardiographic abnormalities at rest is limited.…”