Cardiac Autonomic Dysfunction in Myasthenia Gravis and Relapsing-Remitting Multiple Sclerosis—A Pilot Study

Abstract

This study assessed cardiac autonomic response to head-up tilt test (HUTT) in 23 myasthenia gravis (MG) and 23 relapsing-remitting multiple sclerosis (RRMS) patients compared to 30 healthy controls (HC). Task Force® Monitor was used to evaluate cardiac inotropy parameters, baroreflex sensitivity (BRS), heart rate (HRV), and blood pressure variability (BPV) during HUTT. MG patients were characterized by reduced BRS (p < 0.05), post-HUTT decrease in high-frequency component (p < 0.05) and increase in sympathovagal ratio of HRV (p < 0.05) when compared to controls indicating parasympathetic deficiency with a shift of sympathovagal balance toward sympathetic predominance. Compared to HC, MG patients also showed lower cardiac inotropy parameters, specifically, left ventricular work index (LVWI) during supine rest (p < 0.05) as well as LVWI and cardiac index values in response to orthostatic stress (p < 0.01 and p < 0.05, respectively). Compared to controls, RRMS patients were characterized by lower HRV delta power spectral density (p < 0.05) and delta low-frequency HRV (p < 0.05) in response to HUTT suggesting combined sympathetic and parasympathetic dysfunction. There were no differences in cardiac autonomic parameters between MG and MS patients (p > 0.05). Our study highlights the possibility of cardiac and autonomic dysfunction in patients with MG and RRMS which should be considered in the pharmacological and rehabilitation approach to managing these conditions.

Association of Cardiac Autonomic Responses with Clinical Outcomes of Myasthenia Gravis: Short-Term Analysis of the Heart-Rate and Blood Pressure Variability

“…As a result, the authors hypothesized that Ewing's battery tests showed mainly parasympathetic dysfunction, however, the sympathetic arm of ANS seemed to be slightly affected [14]. These reports confirm our previous findings, which indicate cardiac parasympathetic impairment as well as sympathovagal imbalance in favor of sympathetic tone in MG patients and relatively preserved sympathetic function in response to orthostatic stress [16].…”

“…Myasthenic exacerbation was defined as the clinical deterioration of previously reported muscle weakness lasting more than 24 h unrelated to fever and/or infection, resulting in an increase in the MGFA classification by at least one class. The worsening of symptoms within the last 30 days were considered as a single exacerbation [16]. Thymic pathology was assessed in accordance with the chest CT scan results and available histology findings.…”

“…Considering that MG patients have altered baroreflex sensitivity (BRS) [14][15][16], it makes them more vulnerable to blood pressure fluctuations. Lower blood pressure variability (BPV) is associated with higher risks of cardiovascular events and morbidity [17,18].…”

“…Despite cardiac autonomic dysfunction (CAD) not routinely being diagnosed in MG patients, it is increasingly recognized as an important determinant of subclinical cardiac involvement [9]. It was described in different groups of patients with MG, with [14] and without thymoma [15,16,19], as well as/and in those in myasthenic crisis [20]. Previous evidence using electrophysiological and functional imaging methods showed both sympathetic and parasympathetic nervous system abnormalities and subclinical alterations in cardiac left ventricular function in MG [21][22][23][24][25].…”

Myocardial Injury in Hospitalized Patients with Myasthenia Gravis

“…However, the cardiac dysfunction was also associated with MG. Dysfunction of the cardiac autonomic nervous system with predominant parasympathetic impairment might lead to abnormal baroreflex sensitivity, as well as heart-rate and blood-pressure variability [ 2 , 3 , 4 ]. Recently, myocardial injury was also reported in patients with MG [ 5 ].…”