CORRESPONDENCE: LETTER TO THE EDITOR
Patent Foramen Ovale and the Risk of Cryptogenic Stroke
Ryan G. Schrale, MBBS, FRACP*,
Andrew R.J. Mitchell, BM, MD, MRCP, FESC and
Oliver J. Ormerod, DM, FRCP
* Department of Cardiology, John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom (Email: rschrale{at}hotmail.com).
We would like to congratulate Meissner et al. on their impressive cohort study of patent foramen ovale (PFO) and stroke. However, we hold significant reservations on the stated conclusion that PFO is not an independent risk factor for future cerebrovascular events in the general population (1
).
The population studied by Meissner et al. (1
) was predominately elderly, with a mean age of nearly 70 years (± 13 years). The association of PFO and stroke is much less conclusive in older populations, with conflicting studies (2,3
). Increasing age is associated with increasing incidence of traditional risk factors for atheroembolic stroke—clearly demonstrated in this study where over 50% of subjects were hypertensive and over 50% had visible aortic plaque (1
). It is likely that mechanisms other than paradoxical embolism predominate in these older age groups. The plausibility of a congenital defect suddenly causing a cerebrovascular ischemic event is intuitively much less.
Additionally, it appears no attempt was made to identify those ischemic strokes that were considered "cryptogenic." These represent the minority of the total strokes (4
), but they have been most often associated with PFO (5
).
The management of PFO and cryptogenic stroke is an evolving area (6
). There are currently at least 3 recruiting trials of PFO closure versus medical management. Of note, all specify an upper age limit for enrollment of 60 years (7–9
). The results of these trials are eagerly awaited.
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References
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1. Meissner I, Khandheria BK, Heit JA, et al. Patent foramen ovale: innocent or guilty?Evidence from a prospective population-based study. J Am Coll Cardiol 2006;47:440-445.[Abstract/Free Full Text]2. Jones EF, Calafiore P, Donnan GA, Tonkin AM. Evidence that patent foramen ovale is not a risk factor for cerebral ischemia in the elderly Am J Cardiol 1994;74:596-599.[CrossRef][Web of Science][Medline] 3. Di Tullio M, Sacco RL, Gopal A, Mohr JP, Homma S. Patent foramen ovale as a risk factor for cryptogenic stroke Ann Intern Med 1992;117:461-465.[Abstract/Free Full Text] 4. Sacco RL, Ellenberg JH, Mohr JP, et al. Infarcts of undetermined cause: the NINCDS Stroke Data Bank Ann Neurol 1989;25:382-390.[CrossRef][Web of Science][Medline] 5. Homma S, Sacco RL, Di Tullio MR, et al. Effect of medical treatment in stroke patients with patent foramen ovale: Patent Foramen Ovale in Cryptogenic Stroke study Circulation 2002;105:2625-2631.[Abstract/Free Full Text] 6. Maisel WH, Laskey WK. Patent foramen ovale closure devices: moving beyond equipoise JAMA 2005;294:366-369.[Free Full Text] 7. ClinicalTrials.gov, National Library of Medicine, National Institutes of Health. Evaluation of the STARFlex septal closure system in patients with a stroke or TIA due to the possible passage of clot of unknown origin through a patent foramen ovale (PFO). Available at: http://www.clinicaltrials.gov/ct/show/NCT00201461?order=1
. Accessed January 18, 2006. 8. The Internet Stroke Centre Stroke trials directory. Randomized evaluation of recurrent stroke comparing PFO closure to established current standard of care treatment. Available at: http://www.strokecenter.org/trials/TrialDetail.aspx?tid=482
. Accessed January 18, 2006. 9. Minneapolis Heart Institute. CARDIA STAR trial: a United States randomized clinical trial of the CARDIA STAR patent foramen ovale closure system. Available at: http://www.mplsheart.com/pages/Research.asp?ID=10&SID=28
. Accessed January 18, 2006.
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