What is the treatment for bradycardia (slow heart rate) in patients with Dysautonomia (Autonomic Nervous System dysfunction)?

From the Guidelines

Treatment of bradycardia in dysautonomia should prioritize addressing the underlying autonomic dysfunction while managing symptoms, with first-line treatment including non-pharmacological approaches and medications like fludrocortisone, midodrine, and pyridostigmine, as well as considering permanent pacemaker implantation in severe cases. When it comes to the acute medical management of bradycardia, the 2019 ACC/AHA/HRS guideline 1 provides recommendations for medication dosages. For symptomatic sinus bradycardia or atrioventricular block, the guideline suggests:

• Atropine: 0.5-1 mg IV (may be repeated every 3-5 min to a maximum dose of 3 mg)
• Dopamine: 5 to 20 mcg/kg/min IV, starting at 5 mcg/kg/min and increasing by 5 mcg/kg/min every 2 min
• Isoproterenol: 20-60 mcg IV bolus followed by doses of 10-20 mcg, or infusion of 1-20 mcg/min based on heart rate response
• Epinephrine: 2-10 mcg/min IV or 0.1-0.5 mcg/kg/min IV titrated to desired effect These medications can help increase heart rate and improve symptoms in patients with bradycardia. Key considerations in treating bradycardia in dysautonomia include:
• Increasing fluid intake and salt consumption to help increase blood volume and blood pressure
• Wearing compression stockings and performing physical counter-maneuvers to help manage symptoms
• Monitoring symptoms, blood pressure, and heart rate regularly to assess treatment effectiveness and adjust therapy as needed
• Considering permanent pacemaker implantation in severe cases of symptomatic bradycardia that doesn't respond to other treatments, as recommended by the guideline 1.

From the FDA Drug Label

Patients who experience any signs or symptoms suggesting bradycardia (pulse slowing, increased dizziness, syncope, cardiac awareness) should be advised to discontinue midodrine and should be re-evaluated. The FDA drug label does not answer the question.

From the Research

Treatment of Bradycardia in Dysautonomia

• There is no direct evidence on treating bradycardia in dysautonomia from the provided studies, as they primarily focus on orthostatic hypotension and other aspects of dysautonomia.
• However, it is essential to note that dysautonomia encompasses a range of clinical conditions, including postural orthostatic tachycardia syndrome (POTS), neurogenic orthostatic hypotension (nOH), and cardiovascular autonomic neuropathy (CAN) 2.
• The treatment of patients with dysautonomia is complex and often requires specialized and multidisciplinary evaluation 2.
• For orthostatic hypotension, which can be a symptom of dysautonomia, treatment options include fludrocortisone, midodrine, and droxidopa, as well as non-pharmacological measures such as increasing fluid and salt intake, and using compression stockings and abdominal straps 2, 3.
• Fludrocortisone has been shown to increase blood volume and blood pressure, and is considered a first- or second-line pharmacological therapy for orthostatic hypotension 3.
• A study on familial dysautonomia found that fludrocortisone significantly increased mean blood pressures and decreased dizziness and leg cramping, but not headaches or syncope 4.

Management of Dysautonomia

• Dysautonomias are a heterogeneous group of disorders that can cause variable symptoms, and the causes can be central or peripheral, primary or secondary 5.
• The diagnosis and management of dysautonomia require a comprehensive approach, including initial clinical workups, interpretation of common autonomic tests, and first-line treatments 5.
• A brief review of autonomic impairment associated with acute and long-COVID is also presented in the study 5.

Autonomic Dysfunction

• Autonomic dysfunction can involve the parasympathetic and sympathetic systems, and can lead to various symptoms, including orthostatic hypotension and bradycardia 2, 6.
• The Valsalva, Respiratory, and Orthostatic tests (30:15) are the gold standard methods for the diagnosis of cardiovascular autonomic neuropathy (CAN) 2.
• The Tilt Test can also be used to investigate CAN, but it is not the test of choice for early stages 2.