Patent foramen ovale is significantly associated with cryptogenic stroke in people aged 55 years and older, as well as in younger stroke patients.
Findings from previous studies have suggested such an association, but few earlier investigations have included older patients as subjects. “Proof of a significant relationship” in older patients will have “significant implications for diagnostic and therapeutic management,” Dr. Michael Handke and his associates wrote.
Routine diagnostic testing fails to identify the cause of stroke in approximately 40% of patients. One potential cause is patent foramen ovale (PFO), which can predispose to embolism because it allows right-to-left intracardiac shunting. However, “it has long been debated whether the presence of patent foramen ovale actually does play a causal role in stroke or whether there is only a noncausal statistical relationship,” they noted.
The foramen ovale remains open in approximately 25% of the general population.
To clarify whether the presence of PFO is associated with cryptogenic stroke in older adults, Dr. Handke and his associates at University Hospital Freiburg (Germany) assessed 503 consecutive stroke patients treated at their institution during a 16-month period.
Stroke was classified as cryptogenic in 227 patients.
The prevalence of PFO, with or without a concomitant atrial septal aneurysm, was significantly higher in patients with cryptogenic stroke (34%) than in those whose stroke had a known etiology (12%), judging from findings from transesophageal echocardiography performed within 2 days of stroke onset.
The higher prevalence of PFO in patients with cryptogenic stroke held true both for patients aged 55 years and older and for younger patients. In patients aged 55 and older, PFO was present in 28% of those with cryptogenic stroke, compared with only 12% of those who had stroke of known etiology. In younger patients, the respective prevalences were 44% and 14%, the investigators said (N. Engl. J. Med. 2007;357:2262–8).
At present, “there are no clear guidelines based on randomized trials for therapy if patent foramen ovale is present.” But three ongoing randomized trials are examining the issue and “may clarify the effectiveness of percutaneous closure, as compared with medical therapy,” Dr. Handke and his associates said.
However, as with previous studies of stroke in patients with PFO, all three of these trials enrolled only subjects aged 60 or younger. “Studies that include older patients are needed to develop diagnostic and therapeutic management strategies for this large group of patients,” they noted.