Conference Coverage

PFOs raise stroke risk from ICDs, pacemakers



LOS ANGELES – Patients with a patent foramen ovale and an implanted defibrillator or pacemaker may be perfect candidates for targeted closure of their heart defect, based on a review of more than 6,000 patients who received a device at one U.S. center.

During an average follow-up of nearly 5 years, patients with a patent foramen ovale (PFO) who received an implantable cardioverter defibrillator (ICD) or a permanent pacemaker were more than fourfold more likely to develop a stroke or transient ischemic attack (TIA) compared with implanted device recipients who did not have a PFO, Dr. Christopher V. DeSimone said at the annual scientific sessions of the American Heart Association.

Dr. Christopher V. DeSimone

"We think that this is a high-risk population that might benefit from PFO closure," said Dr. DeSimone, an internal medicine physician at the Mayo Clinic in Rochester, Minn. He acknowledged the poor efficacy of PFO closure for stroke prevention in several recent randomized trials, but noted that patients with a PFO who receive an ICD or permanent pacemaker may constitute a special subgroup that stands to benefit from PFO closure.

"If a patient has a right atrial or ventricular lead and a clot forms and sits there next to the PFO they would be at high risk" for a stroke or TIA, he said in an interview. In fact, trials that have assessed the efficacy of PFO closure explicitly excluded patients with permanent pacemakers as well as many ICD recipients because of their substantially impaired left ventricular function, such as in the CLOSURE I trial (N. Engl. J. Med. 2012;366:991-99). "This needs to be studied prospectively," he added, noting that his study was limited by being retrospective and potentially subject to unadjusted confounding.

Dr. DeSimone and his associates reviewed 6,086 patients who received an ICD or permanent pacemaker at the Mayo Clinic during January 2000 to October 2010. The group included 375 patients with PFOs. Average age of the patients was 67 years; nearly two-thirds were men. About 15% had a history of stroke or TIA, about 44% had atrial fibrillation, and their average CHA2D2-VASc score was 3.1.

During an average follow-up of 4.7 years, the incidence of stroke or TIA was 11% in the PFO patients and 2% in the patients without a PFO. In a multivariate analysis that controlled for baseline demographic and clinical differences, including atrial fibrillation and aspirin and warfarin use, patients with a PFO were 4.6-fold more likely to have a stroke or TIA than were patients without a PFO, a statistically significant difference.

Additional analyses showed that the stroke and TIA rate remained significantly elevated in the PFO patients regardless of whether patients were on treatment with aspirin or on warfarin, and also regardless of whether or not they were older than age 65 or had a history of stroke or TIA, and regardless of whether they had a low or high CHA2D2-VASc score, Dr. DeSimone said.

In contrast to the strong, consistent link between PFOs and stroke or TIA, the researchers saw no significant link between the presence of a PFO and all-cause mortality.

The PFO-related difference in the incidence of stroke and TIA first became apparent about 1 year after device placement. The event curves then continued to diverge more and more over time. He hypothesized that micro-emboli that originate on the device leads pass through the PFO and into the pulmonary circulation, causing increased pulmonary-artery pressures during the year after device placement. The increased right-sided pressure then favors a right-to-left shunt and increased embolization.

Also, the stroke risk in this analysis may have underestimated the true risk posed by the combination of a PFO and a heart device because the methods used to detect PFOs and stroke may not have been optimal in many cases.

Dr. Desimone said that he had no disclosures.

On Twitter @mitchelzoler

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