Cardiac Autonomic Dysfunction in Diabetics Patients With Syncope

2018-10-28 13:53:12 | BioPortfolio


Study hypothesis: cardiac autonomic dysfunction may affect vaso vagal syncope recurrences in type 2 patients with diabetes vs. patients without diabetes.

Background: vaso vagal syncope and its recurrences may be due to alterations in autonomic system function, that may be more frequent in diabetics. Heart rate variability (HRV) is a valid test to study sympathetic and vaso vagal tone dysfunction. However, in this study authors investigated the correlation between HRV alterations and diabetes in a population of patients affected by syncope, and classified as vaso vagal syncope by Head Up Tilt Test (HUT) exam. Secondly, authors assessed these alterations as causes of vaso vagal syncope recurring at 12 months of follow up in type 2 patients with diabetes vs. patients without diabetes. Materials and Methods: In a retrospective multicenter study authors studied 1567 consecutive patients with vaso vagal syncope. All enrolled patients were in stable sinus rate before to perform ECG Holter, and the Head Up Tilt Test (HUT). However, before to perform the HUT all patients performed a 24 hours ECG Holter, to asses sinus rhythm , heart rate, and HRV. Moreover, authors performed a propensity score matching (PSM) analysis to evaluate 121 diabetics vs. 121 non diabetics.


Vaso vagal syncope recurrence is a relevant clinical problem (1). In fact, despite the vaso vagal syncope event is a transient loss of consciousness with rapid onset, short duration, and spontaneous complete recovery after the event, it may be complicated by physical injury (2). Conversely, the syncope recurrence rate is about 35%, and it causes a physical injury until the 29% (3). In addition, the vaso vagal syncope has a frequency between 15% and 39%, with annual number of episodes about 18.1-39.7 per 1000 patients, and an incidence of 6.2 per 1000 person-years, that grows up after 70 years of age with rate annual 19.5 per thousand individuals after 80 years (3). The patients with type 2 diabetes mellitus (T2DM) represent a percentage about the 30% of all the subjects with syncope (4). About the pathophysiology of syncope a central role is played by autonomic nervous system (5). To date, the autonomic nervous system regulates the hemodynamic stability by maintaining a stable blood pressure and heart rate under normal and abnormal physiologic conditions (5). Consequently, the dysfunction of this complex regulatory system, and of its interaction with sensor systems as baroreceptors, mechanoreceptors, chemoreceptors, may alter the vascular reactivity, leading to the clinical event and to future recurrences (5). Multiple factors affecting the autonomic system balance may trigger and cause a syncope event, as the result of an inappropriate response of the autonomic nervous system, with excessive vagal tone, and sympathetic tone withdrawal (2). In this setting, authors may note the diabetes as a common cause of autonomic system dysfunction (6). Moreover, T2DM may cause a severe form of autonomic system dysfunction affecting the cardiac autonomic regulation, and named as cardiac autonomic neuropathy (CAN), (6). Intriguingly, patients with diabetes experience a parasympathetic denervation, with an early augmentation of sympathetic tone, then leading to impaired heart rate variability, resting tachycardia, exercise intolerance, abnormal blood pressure regulation, and orthostatic hypotension (7). In addition, in T2DM there is a compensatory increase in the cardiac sympathetic tone in response to subclinical peripheral denervation (7). However, the T2DM may be seen as a relevant risk factor and a trigger to alter the autonomic system balance, and to cause vaso vagal syncope. Actually, the association between diabetes and autonomic dysfunction and the vaso vagal syncope recurrence at follow up is not well established. Moreover, the recent studies cannot come to definitive conclusion about the diabetes as risk factor and/or as trigger of vaso vagal syncope events, and about its implication to cause future recurrences in affected patients. Conversely, heart rate variability (HRV) is a simple, reproducible and well-recognized method for evaluating sympatho vagal activity (8, 9). However, in this study authors evaluated the autonomic dysfunction as alteration in HRV, and its relevance to cause vaso vagal syncope, and the vaso vagal syncope recurrence in diabetics vs. non diabetics at 12 months of follow up.

Study Design


Syncope, Vasovagal


ecg Holter


Raffaele Marfella




University of Campania "Luigi Vanvitelli"

Results (where available)

View Results


Published on BioPortfolio: 2018-10-28T13:53:12-0400

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Medical and Biotech [MESH] Definitions

Loss of consciousness due to a reduction in blood pressure that is associated with an increase in vagal tone and peripheral vasodilation.

A transient loss of consciousness and postural tone caused by diminished blood flow to the brain (i.e., BRAIN ISCHEMIA). Presyncope refers to the sensation of lightheadedness and loss of strength that precedes a syncopal event or accompanies an incomplete syncope. (From Adams et al., Principles of Neurology, 6th ed, pp367-9)

A condition of fainting spells caused by heart block, often an atrioventricular block, that leads to BRADYCARDIA and drop in CARDIAC OUTPUT. When the cardiac output becomes too low, the patient faints (SYNCOPE). In some cases, the syncope attacks are transient and in others cases repetitive and persistent.

Diseases of the ninth cranial (glossopharyngeal) nerve or its nuclei in the medulla. The nerve may be injured by diseases affecting the lower brain stem, floor of the posterior fossa, jugular foramen, or the nerve's extracranial course. Clinical manifestations include loss of sensation from the pharynx, decreased salivation, and syncope. Glossopharyngeal neuralgia refers to a condition that features recurrent unilateral sharp pain in the tongue, angle of the jaw, external auditory meatus and throat that may be associated with SYNCOPE. Episodes may be triggered by cough, sneeze, swallowing, or pressure on the tragus of the ear. (Adams et al., Principles of Neurology, 6th ed, p1390)

Method in which prolonged electrocardiographic recordings are made on a portable tape recorder (Holter-type system) or solid-state device ("real-time" system), while the patient undergoes normal daily activities. It is useful in the diagnosis and management of intermittent cardiac arrhythmias and transient myocardial ischemia.

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