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There are approximately 1.5 million strokes per year across ESC member countries1 and 800,000 strokes per year in the USA2, almost one-third of which are cryptogenic—that is, they have no obvious cause found.
A patent foramen ovale (PFO) is present in up to 40% of these patients,2 while the prevalence in the healthy population is around 20–25%. There has historically been controversy as to whether this is a causal factor. “It’s difficult to prove cause and effect; however, there is a massive association between PFO and cryptogenic stroke,” says Doctor Iqbal Malik (Hammersmith Hospital, Imperial College London, London, UK), who will be speaking at this afternoon’s session on the current status of PFO closure procedures (Sunday, 14:30 – 15:45; Brahms – The Hub).
“There is now the evidence from three major trials that PFO closure does reduce the risk of recurrent stroke and that it should be offered to selected patients”
Percutaneous PFO closure via a catheter-based approach to reduce the risk of recurrent stroke has been available since the 1990s. However, previously published randomised controlled trials did not demonstrate superiority of device closure over medical therapy (see reference 2). “Now though, with the recently available data from two further trials—CLOSE and REDUCE—and updated long-term results from the RESPECT trial,” explains Dr Malik, “we do have evidence of the benefit of PFO closure.” A meta-analysis published recently in the EHJ, of which Dr Malik is a co-author, included these latest trial data. It confirmed that, in selected patients with cryptogenic stroke, PFO closure is superior to medical therapy for the prevention of further stroke, particularly for patients with moderate-to-large shunts.2
So which patients are most suitable for this intervention? “Selection of the right patients is paramount; it’s not a procedure that is appropriate for everyone,” clarifies Dr Malik. “The patients in the trial had proven stroke and most had large shunts. Thus, an MRI scan to confirm the stroke is necessary, as is assessment of the size of the shunt with bubble contrast echocardiography or transcranial doppler. Those suitable for PFO closure tend to be younger, do not have diabetes or hypertension and are non-smokers,” he says. “Those who do have other cardiovascular risk factors should receive medical therapy instead. For example, there is good evidence for antiplatelets in those with carotid artery atherosclerotic disease, blood pressure lowering medications for hypertension, and anticoagulants in patients with atrial fibrillation. Generally speaking, older patients (for example, aged over 60 years), should receive medical therapy; however, it’s important to consider biological age and individual fitness, not just chronological age.”
PFO closure is an invasive procedure and, as such, there are associated risks. “There’s a 1% chance of serious complications at the time of the intervention, such as stroke, heart attack and internal bleeding,” says Dr Malik. Prior careful assessment of the anatomy of the atrial septum is therefore necessary to minimise procedural-associated risks. As he explains, “Transoesophageal echocardiography will help verify whether there is an atrial septal aneurysm and confirm that there is a heart shunt and not a pulmonary shunt.” During the procedure, Dr Malik uses a balloon across the PFO in order to more accurately assess the gap. “Not all cardiologists use a balloon, but I think it’s the best way to get information as to the size of the PFO and the shape of the tunnel, before selecting the device to use for closure.” Published trials have shown a low rate of procedural-related events—the highest (5.9%) was in the CLOSURE-1 trial, which used the StarFlex device that has since been withdrawn.2 “Currently available devices are associated with a short-term risk of atrial fibrillation, palpitations, etc, but this usually settles within a few weeks and stroke reduction has been proven despite the AF occurring,” he explains.
In considering PFO closure vs. medical therapy Dr Malik emphasises the importance of balancing the benefits with the risks. “I always explain that it’s a ‘belt and braces’ approach to risk reduction. Overall, by undergoing PFO closure a patient will have their risk of a recurrent stroke reduced from approximately 1% to 0.5%; so, although the relative risk reduction is 50%, the actual numbers are small. However, the majority of younger patients who have had a stroke with no obvious cause want to do all they can to reduce the chances of recurrence. We have the technique available—and also now the evidence to show that it is effective—and after two years the 1% risk of the procedure itself has been offset and the patient has a net gain.”
1. Atlas Writing Group. Eur Heart J 2018;39:508–579.2. Ahmad Y, et al. Eur Heart J 2018;39:1638–1649.
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