A stroke occurs when blood flow to a part of the brain is interrupted, either by a blocked or burst blood vessel, causing brain cells to die. Atrial fibrillation (Afib) is a common irregular heartbeat where the heart’s upper chambers beat chaotically and rapidly. This irregular rhythm can affect the heart’s ability to pump blood effectively.
Can a Stroke Lead to Atrial Fibrillation?
While Afib is a well-known cause of stroke, a stroke can also lead to new-onset atrial fibrillation, often called post-stroke atrial fibrillation (AFDAS). This suggests the brain injury might trigger or reveal an abnormal heart rhythm. AFDAS can occur after both ischemic (blockage) and hemorrhagic (bleeding) strokes.
This new-onset Afib is detected during the acute phase following a stroke. It is distinct from cases where Afib was already present but undiagnosed before the stroke event.
Mechanisms Behind Post-Stroke Atrial Fibrillation
A stroke can disrupt the body’s autonomic nervous system, which controls involuntary functions including heart rhythm. Damage to brain regions can lead to an imbalance between the sympathetic and parasympathetic nervous systems. This autonomic dysfunction can contribute to irregular heart rhythms by influencing the electrical activity of the heart’s upper chambers.
Brain injury from a stroke can also trigger a systemic inflammatory response. Inflammatory mediators affect cardiac tissue, potentially leading to electrical and structural changes in the atria. This inflammation can stimulate the heart’s intrinsic nervous system, contributing to Afib.
A stroke can induce acute stress on the heart, sometimes termed “stroke-heart syndrome.” This may manifest as myocardial damage or elevated cardiac enzyme levels, even in individuals without pre-existing heart disease. The brain-heart axis means brain injury can directly influence cardiac function and predispose individuals to arrhythmias.
Differentiating From Pre-existing Atrial Fibrillation and Shared Risk Factors
It is important to distinguish between Afib that existed before a stroke (known atrial fibrillation, KAF) and new-onset Afib detected after a stroke (AFDAS). A stroke can reveal previously undiagnosed Afib that was asymptomatic and may have contributed to the stroke.
Stroke and Afib share several common risk factors, including advanced age, high blood pressure, diabetes, obesity, and pre-existing heart conditions. For instance, patients with AFDAS tend to have fewer pre-existing heart problems and a lower burden of vascular risk factors compared to those with KAF. This suggests that while a stroke can trigger Afib, both conditions often arise in individuals with a predisposition due to shared health factors.
Clinical Implications and Monitoring After Stroke
Due to the potential for new-onset Afib after a stroke, healthcare providers monitor patients carefully to detect irregular heart rhythms. Standard detection methods include electrocardiograms (ECGs) and continuous cardiac monitoring during hospitalization.
Longer-term monitoring, using wearable or implantable cardiac monitors, may be recommended to capture intermittent Afib episodes. The duration of monitoring can influence the detection rate, with longer periods increasing the likelihood of identifying Afib. If new-onset Afib is discovered, management often involves therapies to prevent future strokes, such as anticoagulation medication. Regular follow-up after a stroke is important to manage cardiac health and reduce further complications.