Cardiac involvement and CTG expansion in myotonic dystrophy

Abstract

Although cardiac complications are well known in myotonic dystrophy (DM), patients rarely manifest symptoms of cardiac disease, and if so they most often show conduction abnormalities or arrhythmia. In this study, specific cardiac findings were reviewed in 79 patients with DM. No correlation was found between the cardiac assessments and the CTG expansion. Thus, for a single patient the cardiac involvement in the disease can not be predicted from the findings of the genetic investigation. On the other hand, a clear positive relationship of the PR interval with the QRS duration was revealed, as well as a positive correlation between the age of the DM patient and the QRS duration, which increases with 0,54 ms/year. Systolic dysfunction, evaluated by transthoracic echocardiography, seems to be quite uncommon. In 32 % of the patients with a normal ECG, the 24 h Holter monitoring showed arrhythmias and conduction abnormalities. Based on these findings we recommend a follow up of DM patients not only based on the ECG, but also through 24 h Holter monitoring.

Cardiac involvement over 10 years in myotonic and Becker muscular dystrophy and mitochondrial disorder

“…Improvement of the TTE in a single patient (CR) was attributed to β-blocker therapy. The absent correlation between the SAP and the CTG-repeat size is in line with previous findings [17,19,29,30]. Patient NE with a fractional shortening of 10% died 1 year after the 10-year follow-up.…”

“…Concerning the correlation between the CTG-repeat size and CI there are conflicting results. Some authors showed a clear positive correlation between the CTG-repeat expansion and CI [22,27,28], whereas others could not confirm these results [17,18,29]. Factors in addition to the CTG-repeat size seem to determine severity and progression of CI in MD [30].…”

“…CI in MD results from selective degeneration of the intracardiac, predominantly the infra-nodal conduction system, and of cardiomyocytes, why cardiac complications are the cause of death in up to 30% of the MD cases [14]. The most frequent ECG abnormalities in MD are AV-block, QTprolongation, QRS-prolongation, tachyarrhythmias, and torsades de pointes [15][16][17][18][19]. Atrial fibrillation can be induced in most MD patients and ventricular tachycardia in 20% of them [18].…”

Usefulness of clinical and electrocardiographic data for predicting adverse cardiac events in patients with myotonic dystrophy

“…Although such a correlation between the extent of CTG repeats and the degree of cardiac involvement has been described in some series, others have shown conflicting results (9,17,18,25,(34)(35)(36)(37)(38)(39). Of note is the study by Lazarus et al (17); using precise invasive electrophysiological measurements, the study was unable to show such a relationship between conduction delays and the extent of CTG repeats.…”

Muscular dystrophies and the heart: The emerging role of cardiovascular magnetic resonance imaging

“…Cardiac surveillance, including routine monitoring of electrocardiograms, may detect early DCM development in both DMD and BMD (109). In addition, in 32% of MD1 patients with a normal ECG, the 24 h Holter monitoring showed arrhythmias and conduction abnormalities (110). In MD1, Holter monitoring should be performed on a regular basis, at intervals not >6 months (111).…”