Cardiac arrhythmias in COVID-19: mechanisms and long-term outcomes

COVID-19 can affect the heart’s electrical system during acute infection and, in some people, for months afterwards. Palpitations, atrial fibrillation, inappropriate sinus tachycardia, ventricular ectopy, bradyarrhythmias and syncope have all been reported across the clinical spectrum, from mild community-managed illness to intensive care. The risk is shaped by age, cardiovascular disease, infection severity, inflammation, oxygenation, medications and the presence of myocardial injury.

For clinicians in Australia, the practical question is rarely whether an abnormal rhythm can occur. It is how to distinguish a transient response to infection from myocarditis, pulmonary disease, thromboembolism, autonomic dysfunction or a newly established arrhythmia requiring long-term treatment. Evidence continues to develop, and careful follow-up is especially important when symptoms persist after the acute viral illness has resolved.

How SARS-CoV-2 can disturb cardiac electrophysiology

Several overlapping mechanisms may make the myocardium electrically unstable. Systemic inflammation can alter ion-channel function, impair gap-junction communication and increase atrial irritability. Fever, dehydration, electrolyte loss and sympathetic activation may accelerate the sinus rate or trigger atrial tachycardia. In severe disease, hypoxaemia, acidosis and haemodynamic stress add further strain to the conduction system.

Direct myocardial injury is another possible pathway. SARS-CoV-2-related inflammation may involve cardiomyocytes, the vascular endothelium or the pericardium, while microvascular dysfunction and thrombosis can reduce myocardial perfusion. Myocarditis is clinically important but should not be assumed whenever a patient reports palpitations. Troponin elevation, ventricular dysfunction, chest pain, ECG changes and cardiac magnetic resonance findings need to be interpreted together.

The autonomic nervous system may remain dysregulated after the infection. Some patients develop exaggerated heart-rate responses when standing, exertional intolerance or episodic tachycardia consistent with postural orthostatic tachycardia syndrome. Others experience persistent sinus tachycardia linked to poor sleep, deconditioning, pain, anxiety, anaemia or ongoing inflammation. These causes can coexist, which is why a single explanation may be misleading.

The arrhythmias seen during acute infection

Atrial fibrillation and atrial flutter are among the most frequently recognised clinically significant rhythm disorders in hospitalised patients with COVID-19. They are more common in older adults and people with hypertension, heart failure, coronary disease or structural heart disease. New-onset AF during pneumonia or sepsis may settle as the acute illness improves, yet it can also reveal a substrate that later recurs.

Ventricular premature beats and nonsustained ventricular tachycardia have been described, particularly in patients with myocardial injury, hypoxia or severe systemic illness. Sustained ventricular arrhythmia and cardiac arrest are less common but carry considerable prognostic weight. Bradycardia, sinus pauses and atrioventricular block may reflect inflammation, hypoxia, vagal responses, medication effects or pre-existing conduction disease unmasked by acute illness.

Drug-related electrical effects deserve close attention. Several medicines used during the pandemic raised concern about QT prolongation, especially when combined with renal impairment, hypokalaemia, hypomagnesaemia or other QT-active drugs. A medication review, baseline ECG and repeat monitoring are sensible when clinically indicated. Current treatment should follow contemporary evidence rather than legacy protocols from the early pandemic.

Assessing patients after the acute illness

Follow-up begins with a precise symptom history. Clinicians should clarify whether palpitations are regular or irregular, sudden or gradual, associated with standing or exertion, and accompanied by dizziness, chest pain, breathlessness or syncope. A 12-lead ECG, blood count, electrolytes, renal and thyroid function, and targeted assessment for ongoing pulmonary disease can help identify reversible contributors.

Ambulatory monitoring is useful when symptoms are intermittent or the resting ECG is normal. A Holter monitor may capture frequent ectopy or sustained episodes, while a longer patch monitor can improve detection of paroxysmal AF or episodic supraventricular tachycardia. Echocardiography is appropriate when there is suspected structural disease, persistent tachycardia, abnormal biomarkers or evidence of ventricular dysfunction. Cardiac magnetic resonance is generally reserved for selected patients with suspected myocarditis or unexplained myocardial injury.

Red flags include syncope during exertion, sustained chest pain, marked breathlessness, haemodynamic instability, a persistently rapid resting rate, sustained ventricular arrhythmia and significant troponin elevation. These findings warrant urgent assessment rather than reassurance based solely on a history of COVID-19. Clinicians can also use the practical guide to frame rhythm assessment in patients whose congenital or structural heart disease complicates interpretation.

What long COVID means for rhythm care

Persistent palpitations are common in post-acute COVID clinics, but symptom burden does not always correlate with a dangerous rhythm. A normal ECG and reassuring ambulatory monitor can be valuable, although they do not invalidate the patient’s experience. Management may involve hydration, gradual conditioning, sleep support, treatment of anaemia or thyroid disease, and a paced return to activity. Rapid escalation of exercise can worsen symptoms in people with post-exertional deterioration.

Postural tachycardia and inappropriate sinus tachycardia require an individualised approach. Clinicians may consider increased fluid and salt intake where appropriate, compression garments, physical counter-manoeuvres and recumbent exercise progression. Beta blockers or other rate-modifying medicines may help selected patients, but asthma, hypotension, fatigue and coexisting autonomic symptoms must be considered. Specialist input is advisable when the diagnosis remains uncertain or symptoms substantially limit daily life.

AF identified after COVID-19 should be managed according to established principles. Stroke risk assessment, anticoagulation decisions, rate or rhythm control, and management of hypertension, obesity, sleep apnoea and alcohol exposure remain central. COVID-19 may be the trigger that brings AF to attention, rather than the sole cause. A documented episode should therefore prompt appropriate longitudinal follow-up rather than being dismissed as a temporary infection-related event.

Outcomes and risk across different patients

The greatest short-term risk occurs in people with severe infection, critical illness, myocardial injury or pre-existing cardiovascular disease. Arrhythmias in intensive care often reflect a combination of inflammation, catecholamine excess, hypoxia, fluid shifts and organ dysfunction. Outcomes improve when clinicians correct reversible triggers, treat the underlying respiratory or circulatory problem and avoid unnecessary proarrhythmic exposure.

Long-term data suggest that most patients with uncomplicated infection do not develop a persistent malignant arrhythmia. However, population studies have found increased rates of cardiovascular diagnoses after COVID-19 compared with matched controls, particularly among people who had severe illness or multiple risk factors. The excess risk may involve AF, heart failure, ischaemic disease and thromboembolic events, but estimates vary according to the variant period, vaccination status, healthcare access and how outcomes are recorded.

Australian practice has its own access considerations. A patient in a regional town or in remote Western Australia may face a long journey for electrophysiology testing, while metropolitan services in Sydney, Melbourne, Brisbane, Perth and Adelaide can have different referral pathways and waiting times. Telehealth, local ECG acquisition and shared-care arrangements can reduce gaps, but they should not replace urgent in-person review when red flags are present. Aboriginal and Torres Strait Islander patients may also encounter geographic and systemic barriers, making culturally safe communication and coordination with Aboriginal Community Controlled Health Services important.

Building a durable clinical pathway

A sensible pathway separates immediate danger from persistent but lower-risk symptoms. During acute infection, clinicians should stabilise oxygenation and circulation, correct electrolyte abnormalities, review medicines and investigate chest pain, syncope or biomarker elevation. In the recovery phase, the focus shifts to rhythm documentation, structural assessment when indicated, cardiovascular risk reduction and a clear plan for escalation.

Patients benefit from knowing which symptoms require emergency care and which can be recorded for review. A symptom-and-pulse diary can identify relationships with posture, meals, sleep, exertion and medication timing. Wearable devices may provide useful alerts or rhythm strips, but they can also generate false positives and should support, rather than replace, clinical interpretation. Consumer data should be assessed alongside an ECG-quality recording whenever possible.

Research priorities include longer follow-up, consistent definitions of post-COVID arrhythmia, better separation of infection effects from healthcare disruption, and inclusion of diverse communities. The Journal of Arrhythmia provides an open-access setting for current research, reviews and clinical guidance relevant to electrophysiology, pacing, ablation and device care. Ongoing evidence will help clarify which patients need specialist surveillance and which can be safely managed in primary care.

Clinicians should also consider the practical realities of Australia’s healthcare system. Public hospitals, private cardiology practices, general practitioners and rehabilitation services may all share responsibility for follow-up. Clear referral letters, accessible test results and explicit ownership of anticoagulation or monitoring decisions can prevent patients from falling between services. For people living far from tertiary centres, a well-coordinated local plan may be more valuable than a series of disconnected specialist appointments.

COVID-19 has expanded awareness of how infection, inflammation, autonomic disturbance and structural heart disease interact with cardiac rhythm. Apply a measured approach: document the rhythm, identify reversible triggers, investigate myocardial injury when indicated, treat established arrhythmias according to guideline-based care and arrange follow-up proportionate to risk. Clinicians and researchers can use open-access electrophysiology evidence to refine pathways and improve long-term outcomes for patients across Australia.