Can the Rhythm Method Reduce Stroke after PFO Closure?

In this issue of the Journal of Invasive Cardiology, Alaeddini et al report on the incidence of atrial tachyarrhythmias (AT) in their series of 71 patients who had closure of a patent foramen ovale (PFO) performed for cryptogenic stroke or orthodeoxia.¹ There are many drawbacks to this study, not the least of which is the fact that only patients who complained of palpitations were the ones who were further evaluated by Holter monitoring. In addition, only 48-hour Holter monitoring was performed, rather than longer “event” monitoring, which might have uncovered more AT. Hence, the chances are high that there was significant underreporting of actual AT, as the authors point out. They point out some important observations from their data: 1) Patients with AT had a trend toward a larger left atrium on apical echocardiographic view, though the difference in left atrial size in the parasternal view (and right atrial size) were not statistically significant. 2) AT occurred more frequently in patients who had larger closure devices placed. 3) The incidence of AT in their patients was 7%. Their data are generally in keeping with other studies on the incidence of AT after PFO or atrial septal defect closure that are already in the literature. The incidence of AT after closure ranges in those studies from slightly less than 1% to 6%. Of the 5 patients in their study who had AT, 3 had atrial fibrillation (AF), and in the other reports, AF (either brief or fixed) occurred as the AT. Since AF is arguably the AT most likely to be associated with atrial thrombi and the potential for thromboembolism, this is an important issue. Most disturbing in their report is that 1 patient with AF developed thrombus on both sides of the closure device (she underwent surgical removal). We are not told about what kind of antithrombotic or antiplatelet therapy was given to their patients. What can we learn from this report? Certainly it emphasizes that atrial fibrillation after closure occurs with unsettling frequency and that the potential for systemic thromboembolism, either from the device or from other sources such as the left atrial appendage or the body of the left atrium, is real. Thus, the prudent interventionalist should counsel patients about the potential risks associated with AT after closure and ask patients to report palpitations whenever they occur post-closure. Though clearly not foolproof, at a minimum, Holter monitoring should be used to evaluate the type of AT and if appropriate treatment with warfarin should be instituted if AF occurs. The whole issue of atrial arrhythmias after PFO closure may account for one of the most vexing problems we face as we try to reduce the incidence of recurrent cryptogenic stroke by PFO closure. As we all know, closure in no way guarantees that cryptogenic strokes will not recur. Multiple nonrandomized reports have shown that recurrence rates of stroke after successful percutaneous closure is about 2–4%. Is it just fortuitous that the incidence of AT after closure is in a similar range, or is there perhaps a connection? If there is, perhaps it is not failure of closure that accounts for the incidence (albeit low) of cryptogenic stroke after closure, but rather the occurrence of AT that is the culprit. One could argue that all patients should be monitored post-closure and treated with warfarin if AT is detected. Or, perhaps patients with enlargement of one or the other atrium need to be anticoagulated with warfarin rather than aspirin and clopidogrel (the latter for a variable number of months). More data are needed to answer these questions, but they are intriguing, and the answers may help us to further minimize the risk of recurrence of stroke after PFO closure.

1. Alaeddini J, Feghali G, Jenkins S, et al. Frequency of atrial tachyarrhythmias following transcatheter closure of patent foramen ovale. J Invasive Cardiol 2006;18:365–368.