Natural history of cardiac involvement in myotonic dystrophy (Steinert’s Disease): A 13-year follow-up study

Abstract

Myotonic dystrophy (MD) is associated with a wide spectrum of cardiac abnormalities, but only a few longitudinal studies have investigated the natural course of heart disease in MD. To assess whether neuromuscular involvement significantly predicts cardiac disorders in MD, 83 patients with various grades of disease severity were enrolled in a 13-year follow-up study (mean, 60.6 +/- 37.8 months) that included periodic physical and instrumental cardiac examinations (standard and Holter electrocardiography, echocardiography). During follow-up, muscular disease worsened clinically in 9 patients (11%) whose baseline severity grade changed accordingly; only 3 of them demonstrated parallel worsening of cardiac disturbance, however, compared with a large number of patients who showed additional cardiac abnormalities. These included further worsening of pre-existing pathologic features (19/83) and the appearance de novo of serious arrhythmias and/or conduction defects (23/83). Pacemaker implantation was necessary in 11 of 83 patients (13.2%) who had symptomatic bradyarrhythmias, bifascicular block, and P-R prolongation with a His-to-ventricle interval exceeding 55 ms, as documented by electrophysiologic study. Eight (9.6%) patients died: 2 from noncardiac and 1 from unknown causes, 1 from heart failure, and 4 from sudden death closely related to documented ventricular tachycardia. The incidence and seriousness of arrhythmic and conduction disturbances correlated with the severity of the muscular involvement. Nevertheless, cardiac and muscular disease did not show a linear progression. Cardiac involvement generally worsened more rapidly than did skeletal muscle disease.

Cardiac manifestations of myotonic dystrophy type 1

“…Nine (n = 609) studies reported echocardiographic findings on LVEF above or less than 50% [10][11][12][13][14][15][16][17][18]. The patients' gender was not reported in 266 patients.…”

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

“…Many studies have been performed to find variables that could help predict which patients are at increased risk for an adverse cardiac event (15)(16)(17)(18)(19)(20)(21)(22)(23). These studies, using different approaches, usually showed that advancing age and severity of neurological impairment, and a higher degree of conduction disturbance, assessed either by surface electrocardiogram (ECG) or by electrophysiological study, correlate with a worse outcome.…”

Abnormal contractile activity and calcium cycling in cardiac myocytes isolated from dmpk knockout mice

“…First degree (prolonged) AV conduction block is common in DM1. Higher grade AV conduction block and ventricular tachycardia are associated with "sudden death" in DM1 (10,29).…”