Postural Orthostatic Tachycardia Syndrome (PoTS) is a debilitating, under-recognised condition and co-morbidity of ME/CFS. It is characterised by an abnormal rise in heart rate, in addition to other symptoms, when a person transitions to an upright position. The name PoTS breaks down as follows:
- Postural: Refers to the body’s position or posture. In PoTS, symptoms are triggered/worsened by a change in posture.
- Orthostatic: Refers to an upright posture. It follows that PoTS symptoms are related to sitting- or standing up.
- Tachycardia: Means a fast heart rate. The key diagnostic feature of PoTS is a persistent and abnormal increase in heart rate after assuming an upright posture.
- Syndrome: This refers to a collection of symptoms/signs that occur together. In PoTS there are many symptoms, such as dizziness/light-headedness, which occur alongside an elevated heart rate. These can range from mild to severe, often fluctuating from day to day.
PoTS is thought to affect at least 0.2% of the general population and is more prevalent in females aged between 15 and 50, although it does occur in males. Estimates of prevalence of PoTS as a comorbidity in ME/CFS vary hugely, ranging from 6% to 70%. One reason for the lower estimates and discrepancy across studies could be that many symptoms overlap with other conditions, including ME/CFS, therefore PoTS is underdiagnosed.
PoTS can be so debilitating because many everyday activities, such as drinking coffee and taking hot showers, may aggravate symptoms and majorly impact quality of life. Identifying/diagnosing PoTS is important because there are management strategies available that could potentially alleviate some of the disease burden.
PoTS symptoms
PoTS symptoms are diverse and include, but are not limited to –
Cardiovascular/Respiratory
- Increased heart rate (tachycardia) – a persistent heart rate increase of 30 beats per minute (or 40 for individuals aged 12 to 19) upon standing is the hallmark sign of PoTS
- Palpitations (sensation or awareness of heartbeat)
- Dizziness/light-headedness
- Fainting or near-fainting
- Shortness of breath
- Chest pain
Neurological
- Cognitive difficulties (brain fog)
- Headaches
- Visual problems
- Sense of anxiety
Gastrointestinal/Urinary
- Nausea
- Gut problems
- Bladder problems
General
- Fatigue
- Sleep disturbances
- Temperature sensitivity and sweating
- Shakiness/tremor
PoTS Triggers
Many factors can worsen PoTS symptoms, such as, but not limited to –
- Dehydration
- Environmental heat
- Alcohol/Caffeine
- Large heavy meals – particularly high carbohydrate meals
- Menstruation/periods
- Prolonged standing or sitting
- Prolonged bed rest/deconditioning – Note: Blitshteyn and Fries 2016 emphasise that PoTS is not caused by deconditioning rather deconditioning “can occur secondary to prolonged bed rest and chronic inactivity in patients with POTS”. Subsequently, PoTS symptoms can be made worse by deconditioning.
- Exercise – Note: According to PoTS UK, “whilst occasional exertion can exacerbate symptoms, an ongoing exercise program can improve symptoms, and is often recommended by specialists.” It is important to recognise that the situation is more complex for people with comorbid ME/CFS, as graded exercise therapy was removed as a recommendation by NICE due to extensive patient reports of harm.
Underlying mechanisms of PoTS
According to the National Institute of Neurological Disorders and Stroke, “POTS often begins after a pregnancy, major surgery, trauma, or a viral illness”.
PoTS UK and Standing Up to POTS detail three main subtypes of PoTS (although there is overlap) –
- Hyperadrenergic PoTS
“Hyper” means excessive, and “adrenergic” refers to adrenaline (epinephrine), noradrenaline (norepinephrine) and other closely related hormones/neurotransmitters. Hyperadrenergic PoTS is characterised by excessive norepinephrine and an overactive sympathetic nervous system upon standing. There are several prominent symptoms of PoTS including a more extreme heart rate increase (in comparison to other subtypes), increased blood pressure, migraines, nausea, anxiety and tremor.
- Neuropathic PoTS
“Neuro” refers to nerves, and “pathic” relates to disease. Neuropathic PoTS is characterised by impaired function of the sympathetic nervous system and is often associated with damage to small nerve fibres (small fibre neuropathy) affecting ability to regulate blood vessel constriction. This typically results in widening blood vessels and blood pooling in the limbs and abdomen, cyanosis (turning blue) of the feet when standing/warm, and loss of sweating in the extremities.
- Hypovolaemic PoTS
“Hypo” means low, and “volaemic” refers to blood volume. Hypovolaemic PoTS is characterised by low blood volume. This leads to less blood return to the heart and a compensatory increase in heart rate and force of heart contraction in order to improve blood circulation.
Diagnosing PoTS
Various conditions, including ME/CFS, Ehlers-Danlos syndrome, hypermobile spectrum disorder, mast cell activation syndrome (MCAS), inappropriate sinus tachycardia, and autoimmune disorders, may be associated with PoTS. It is vital to diagnose PoTS separately, as management approaches can differ from co-occurring conditions.
The primary diagnostic test for PoTS is the active stand test – a short test involving heart rate and blood pressure monitoring – designed to evaluate how a person’s cardiovascular system responds to a change in posture, particularly standing up. If diagnosis remains uncertain, patients may undergo a tilt table test, and additional tests like ECGs and blood tests are used to rule out other conditions.
Misdiagnosis of PoTS is a significant concern, primarily due to the overlap of symptoms with other conditions and limited awareness among many medical professionals. Patients may receive inaccurate diagnoses such as anxiety, depression, vasovagal syncope, or ME/CFS. According to PoTS UK, the average time to diagnosis from symptom onset is 7 years. This underscores the pressing need for increased awareness and education about PoTS to facilitate more timely diagnosis and management, ultimately enhancing the quality of life for individuals living with PoTS.
PoTS Management
Considering the numerous aggravating factors and different underlying mechanisms of PoTS, management requires a multifaceted approach tailored to individual needs. This can include, but is not limited to:
- General advice/lifestyle changes, such as avoiding triggers, increasing fluid intake, and gentle exercise
- Interventions such as wearing compression garments e.g. abdominal binders and stockings
- Medications such as beta-blockers to control heart rate
One of the challenges in dealing with PoTS is the lack of a separate clinical guideline provided by the National Institute for Health and Care Excellence (NICE). For those seeking information, the NHS website directs individuals to the PoTS UK website as a valuable resource based on patient experience and opinion.
According to a review into PoTS, whilst the long-term prognosis of PoTS is not well explored, it is estimated that around 50% of patients spontaneously recover within one to three years. Another study mentioned that those with hyperadrenergic PoTS will require lifelong treatment. Nevertheless, treatment is generally thought to improve quality of life regardless of whether recovery is possible.
ME/CFS vs. PoTS
ME/CFS is associated with various conditions, among which PoTS stands out due to its significant symptom overlap. Whilst there are numerous commonalities, there are also key differences between them.
Fatigue – Both PoTS and ME/CFS are associated with fatigue, hence it is important for people with ME/CFS who have comorbid PoTS to understand that treatment options are available for the latter (therefore potentially reducing overall fatigue levels).
Orthostatic Intolerance – Individuals with ME/CFS patients often report orthostatic intolerance, meaning that symptoms worsen upon assuming an upright position, despite not qualifying for a PoTS diagnosis.
Exercise Contraindication – Perhaps the most significant difference between PoTS and ME/CFS is the response to exercise. Whilst exercise programs can be beneficial for some PoTS patients when carefully managed, graded exercise therapy is not recommended in the NICE guidelines for ME/CFS due to its potential for harm. For many with ME/CFS, exercise can lead to post-exertional malaise (PEM) and significant worsening of symptoms.
In relation to prognosis – whilst individuals with ME/CFS may report improvements in symptoms over time, ME/CFS has lower prospects of recovery than PoTS.
Conclusion
Awareness of PoTS amongst healthcare professionals remains limited, and its significant symptom overlap with conditions, including ME/CFS, likely contributes to underdiagnosis. Living with PoTS is challenging, and it can significantly impact everyday activities, hence the importance of timely diagnosis and appropriate management to improve quality of life.
PoTS Awareness Day, October 25th, is a vital occasion for raising awareness and advocating for those affected by PoTS. By sharing information about the condition, and clarifying its differences from ME/CFS, we can foster a better understanding of both conditions.