New Research Reveals How Closing a Hole in the Heart May Reduce Migraine Headaches
When it comes to migraines, could the heart of the matter be a matter of the heart?
Migraines headaches affect up to 12% of the US population. Identifying effective therapeutics for those who suffer from migraines can be challenging, and no one medication has proven to be a cure-all. Medical researchers are investigating an innovative method of non-medical treatment that, rather than targeting the brain directly, focuses on another vital organ — the heart.
A hole new approach
Approximately 20 to 25% of adults possess what is called a patent foramen ovale (PFO). A PFO is a type of atrial septal defect (ASD, image on the left) that can essentially be described as a hole between the upper two of the heart’s four chambers. Generally too small to cause any adverse health effects, PFOs are often considered benign, and many individuals with a PFO may never know they carry such a defect.
The foramen ovale is an embryonic structure beneficial for life in the womb that closes naturally a few months after birth. However, it may fail to seal fully in some individuals thereby remaining patent or open.
A deeper dive into PFO closure
A link between the heart and migraine headaches was first recognized in underwater divers. Because of pressure changes that occur when ascending to the surface rapidly, air bubbles can develop in a diver’s veins. If a diver happens to have a PFO, the bubbles can travel from the veins across the PFO and into the diver’s arterial circulation. From there, the air bubbles can move to the brain and other organs causing decompression sickness.
In order to avoid decompression sickness, some divers, in addition to ascending more slowly, have also undergone surgical closure of their PFOs. A small group of divers with a history of migraines noticed another benefit to having their PFOs closed. Besides experiencing fewer symptoms of decompression sickness, they were also experiencing fewer migraines.
How exactly is a PFO closed? As shown in the figure above, a catheter is inserted into a large vein in the thigh, advanced toward the heart, and passed through the PFO. A mesh containing a nickel-titanium alloy is then deployed on either side of the PFO and the catheter is removed leaving behind a patch to cover the hole. After the procedure patients are required to take one or two antiplatelet medications for at least six months in order to prevent blood clots from forming near the device.
Examining the link between PFO and migraine
Because of the subjective nature of headaches, specific headache disorders and their subsets can be difficult to define. In general, migraine headaches can be broken down into two major groups: migraine with and without aura. An aura is a visual or auditory sensation that patients sometimes experience just prior to a migraine. Auras can signal that a migraine is imminent. Migraines with aura are also referred to as classic migraines.
As it turns out, PFOs are more common in patients with migraines than they are in the general population. Furthermore, PFOs are even more common in those who suffer from migraines with aura and can occur in up to 50% of such individuals.
Observational studies have shown that successfully closing a PFO is associated with a greater than four-fold reduction in migraine burden, but until recently, the benefit of PFOs closure had yet to be demonstrated by the highest quality evidence in medicine — a randomized controlled trial (RCT).
In February of 2021, a pooled analysis of two RCTs was published in the Journal of the American College of Cardiology (JACC). The 337 patients selected for the study had been suffering from migraines despite trying 2 or 3 migraine medications. Participants were randomized to two cohorts: an intervention group who would undergo PFO closure and a control group who would receive medical treatment alone.
Prior to the intervention, there was no difference between these groups in regards to the average number of migraine days and migraine attacks per month. The average age was 43, and a large portion of patients (257) experienced migraine with aura.
Authors of the pooled analysis explain, “The subjects filled out a daily questionnaire including questions about the quality and duration of headache and associated symptoms.” One year later the groups were evaluated and the results were striking.
Unpacking the latest data
The average decrease in migraine days per month in the PFO closure group was 3.1 days compared to 1.9 days in the control group (panel A below). Similarly, the number of migraine attacks per month decreased by 2.0 in the closure group compared to 1.4 among controls (panel B below). The most dramatic findings, however, were that 9% of patients in the closure group experienced complete resolution of their migraines compared to only 0.7% of controls (panel D below).
These results raise a number of important questions. For instance, why was such a significant improvement observed in the control group? This may be related to the characteristics inherent in this cohort. Even though some participants of the study did not undergo PFO closure, they still received medical treatment for their migraines rather than no treatment or a placebo. Therefore it is not surprising to see some degree of improvement in a control group under this type of design.
Limitations of the study were highlighted in an associated commentary also published in JACC. A portion of the patients in the control group were blinded by undergoing a sham PFO closure. However, other patients in the control group were treated medically without undergoing a sham procedure. Being unblinded and aware that they were in the control group could have influenced the answers those patients provided on their headache questionnaires and, in turn, may have affected the results of the study.
In terms of safety, PFO closure appears to be low risk. Nine procedure-related and four device-related adverse events occurred among 245 subjects who received devices. Fortunately, all of these events were transient and resolved on their own. The authors summarize, “PFO closure was safe and significantly reduced the mean number of monthly migraine days and monthly migraine attacks, and resulted in a greater number of subjects who experienced complete migraine cessation.”
Next moves
Although the results of this study are promising, more convincing data is required to determine if a change in the standard of care for migraines warranted. So until more research is conducted, don’t expect PFO closure to be the first treatment your doctor recommends for a migraine.
Fortunately, an important investigation is on the horizon. This year, patients are being enrolled in the RELIEF Migraine trial which is a multicenter study taking place across 25 sites in the United States. This study will compare PFO closure with sham closure in a cohort of patients whose migraines are partially responsive to antiplatelet medication. This investigation may shed light on the theory that some migraines are provoked by platelet activity that under normal circumstances is diminished when blood flows through the lung circuit before arriving at the heart, but remains a trigger for headache when platelets pass across a PFO traveling directly to the head and brain.
Attempting to comprehend the vast complexities of the human body can be enough to cause a headache, but with time and a little bit of luck, I expect science will uncover a cure for that ailment too.
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