[Description of the resting electrocardiogram in a series of patients with myasthenia gravis].
Myasthenia gravis (MG) is a disease characterized by the presence of acetylcholine receptor-directed autoantibodies. Functional cardiac disorders are the most common since there is no neuro-muscular plate in the heart. Autonomic nervous system is involved in MG, but the cardiac manifestations of such an involvement remain unclear. Previous EKG studies in patients with MG show heterogeneous results.


METHODS
A retrospective, descriptive and observational study was performed to know the main electrocardiographic characteristics and some autonomic nervous function in a series of patients with MG.


RESULTS
One-hundred seventeen patients with EKG were analyzed. Twenty-eight were 47.9 +/- 20 years-old males, and 89 were women of 35.2 +/- 7.7 years (p = 0.001). 49 (41.9%) EKG had no changes, while 68 (58.1%) did. The main QT dispersion was 35.5 +/- 18.4 ms among those with some anomaly (p = 0.27). In 54 (78.3%) patients with an abnormal EKG there was T wave alternans, which was also present in 35 (71.4%) (p = 0.32) patients with normal EKG.


CONCLUSIONS
MG is frequently associated to unspecific EKG changes. Dynamic electrocardiography allows a precise evaluation of the kind of cardiac involvement derived from MG, specifically the one related to the autonomic function, that is apparently affected in both the sympathetic and parasympathetic arms.
D000328:Adult; D000368:Aged; D015897:Comorbidity; D004562:Electrocardiography; D005260:Female; D006321:Heart / Q000503:physiopathology*; D006329:Heart Conduction System / Q000503:physiopathology; D006331:Heart Diseases / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009157:Myasthenia Gravis / Q000150:complications / Q000453:epidemiology / Q000503:physiopathology*; D009369:Neoplasms / Q000453:epidemiology / Q000503:physiopathology; D012146:Rest; D012189:Retrospective Studies; D013959:Thyroid Diseases / Q000453:epidemiology / Q000503:physiopathology