Visual Disturbances after AFib Ablation

Temporary visual disturbances and migraines after an ablation can be scary but unfortunately are common. Patients are not always warned of this possibility which can result in greater anxiety. The reasons for these effects are poorly understood but recent results of the recently published TRAVERSE study have provided much needed insights into this phenomenon.

Migraines and AFib Ablation

Migraines are recurrent headaches often characterised by pain, nausea, and sensitivity to light and sound. Compared to typical headaches, migraines can be associated with unusual neurological symptoms such as visual disturbances known as auras. The visual disturbances are often characterised by flashing lights, zig-zag lines, or blurred vision.

Any example of the visual disturbance experienced during a migranous aura

For some patients, these symptoms can occur for the first time in the days after atrial fibrillation (AF) ablation procedures leading to understandable anxiety and concern, especially if you have not been warned about them but been told about the rare risk of stroke.

Fortunately, migrainous auras resolve within a few days; however, we (the medical community) have a poor understanding of why they occur after the procedure in the first place.

Why do Migraine and Auras happen after an Ablation?

In general, migraine auras are thought to result of a wave of altered electrical activity moving slowly across the brain's visual cortex, temporarily disrupting normal vision.

The parietal (yellow) and occipital (blue) cortices are the areas of the brain associated with vision. These areas are effected during visual disturbances during migrainous aura.

The association between migrainous auras and AF ablation is not fully understood. One prevailing hypothesis (still the most commonly cited hypothesis by faculty at Barts on my informal survey today!) has been that it is a result of the trans-septal puncture step of the procedure. The trans-septal puncture is the intentional creation of a small hole created between the top chambers of the heart during the procedure so that the ablation catheter can reach the target areas that trigger AF.

This is an image of the heart to show a trans-septal puncture being performed through a sheath (the blue tube). The catheter is passed up the vein and into the right atrium. A small needle tip is then advanced out of the end to puncture the septum to access the left atrium. The sheath is then passed over this needle into the left atrium and the needle is then withdrawn. Catheters can then be passed through the sheath into the left atrium to perform the ablation procedure. The image is taken from here.

It has been suggested that this puncture might allow substances or tiny blood clots (emboli) to cross from the body and the right side of the heart to left side of the heart, which is connected to the brain. These chemicals and emboli may be the potential trigger for migrainous auras. The basis for this hypothesis is largely driven by registries of people that suffer from migrainous aura who have shown a higher incidence of a congenital (from birth) hole between these two heart chambers. When this hole naturally occurs, it is called a PFO or an ASD and some patients with migraine may even pursue procedures to close these holes, although there is no strong evidence to support this as a beneficial treatment for migraines.

However, a logical hypothesis should always be tested through randomised controlled trial, and that is what the investigators of the TRAVERSE trial have now published and the results were not as expected.

The TRAVERSE Trial

In this randomised trial, 146 patients were recruited from multiple EP centres across the USA. These patients were due to undergo left ventricular ablation procedures for arrhythmias originating from the lower chambers of the heart i.e. not AF. These patients were randomly assigned either have there catheters delivered through the trans-septal route (requiring the trans-septal puncture) or by passing them directly through a different blood vessel connected directly to the left ventricle (i.e. without any trans-septal puncture). The patients were similar in the two groups and had largely similar treatments apart from this difference in the route of catheter access. Each patient also underwent a brain MRI the day after their procedure to detect potential brain emboli and they completed a validated migraine assessment one month later.

The key findings from the TRAVERSE trial:

There was no significant difference in the rate of migrainous auras between patients undergoing the trans-septal puncture route versus those undergoing the non-trans-septal puncture approach, reported by 16% and 14% of participants in each group respectively.
Patients with acute brain emboli detected in the visual cortex of the brain on MRI were significantly more likely to experience visual auras in the days after their ablation procedure (38% vs. 11%).
After adjusting for other factors, the finding of brain emboli in the visual cortex on MRI were associated with a 12-fold increase in the likelihood of experiencing visual auras.

This is a forest plot. The bars represent the risk of having a visual aura event after an ablation procedure in the TRAVERSE trial based on the presence of the stratifying feature. If a horizontal bar does not overlap with the central '1' line it means the feature is significantly associated with the risk having an aura. Based on this study, having an emboli in the occipital or parietal regions of the brain and having a previous visual aura before the ablation were both risk factors. Image taken from here.

The study authors conclude that migraine-related visual auras after ablation are likely related to these small brain emboli affecting the visual processing areas of the brain. Although these emboli are likely a result of the ablation procedure, they are not associated with the trans-septal puncture step itself. There was no specific risk factor or step that was associated with the emboli risk and these were seen in patients in both groups receiving either approach.

Importantly, they highlighted that these emboli usually resolve spontaneously on later imaging within weeks, correlating with the typically temporary and spontaneously resolving nature of migrainous auras too.

The findings of the TRAVERSE trial also suggests that brain emboli following cardiac procedures might be more common than we anticipate and although they are not resulting in a stroke they are not completely harmless, as evidenced by these transient visual disturbances. Before extrapolating these results to AF ablation procedure though, it is important to remember though that these patients were having different procedures for different heart rhythm issues. They also had a much higher rates of co-morbidities such as diabetes or atherosclerotic disease than typical patients with AF.

Summary

This trial has provided very welcome data on a common and poorly understood side effect of ablation procedures.

The data argues against the prevalent hypothesis that the trans-septal puncture and inter-atrial shunting causes the visual disturbances and suggests they are associated with micro emboli lodging in the visual cortex of the brain.

While the idea of brain emboli can sound concerning, repeated MRI studies suggest that these typically resolve by themselves, and we can also expect the spontaneous resolution of migraine symptoms. Nonetheless, the possibility of visual disturbances after ablation should be discussed with patients to mitigate potential anxiety and fear of the unknown.

Of note, any new neurological symptoms following AF ablation should still be promptly reported and assessed to rule out any other causes and to look for any other symptoms too.

The TRAVERSE trial: Elias A, Tung R, Gerstenfeld EP, Hue TF, Lin F, Cheng J, Weiss JP, Tzou WS, Hsia H, Ehdaie A, Cooper DH, Bunch TJ, Arkles J, Nazer B, Lee A, Hadjis A, Nguyen DT, Chelu MG, Moss J, Hsu JC, Valderrábano M, Bhave PD, Montenegro G, Kim AS, Dillon WP, Marcus GM. Leveraging A Randomized Trial to Assess Relationships between Transeptal Puncture, Brain Emboli, and Migraine Symptoms. Heart Rhythm. 2025 Jun 26:S1547-5271(25)02614-1. doi: 10.1016/j.hrthm.2025.06.035.