J Thorac Cardiovasc Surg 2000;119:751-752
© 2000 The American Association for Thoracic Surgery
SURGERY FOR CONGENITAL HEART DISEASE |
Commentary
Richard A. Jonas,
Boston, Massachusetts
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Introduction
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 Introduction
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The article by Balling and associates addresses the very important issue of intracardiac thrombus formation and its possible prevention by routine anticoagulation in patients after the Fontan procedure. Thromboembolic stroke in a child is a devastating complication that often has lifelong consequences for the child and family. Furthermore, evidence is steadily accumulating that there is indeed a procoagulant state with Fontan physiology. For example, recent work by Jahangiri and associates, both in London and in Boston, has demonstrated a decreased level of protein C and protein S, as well as an increase in some procoagulant factors.
Balling and associates reviewed the case histories of 52 patients late after a Fontan procedure. All patients had undergone transesophageal echocardiographic (TEE) studies as part of a program intended to identify the incidence of thrombus in these patients, although it appears that much of the non-TEE patient-related data were not collected prospectively, but through a retrospective chart review. They identified a remarkably high incidence of intra-atrial thrombi (almost all in the right atrium), although not inconsistent with previous reports. They conclude that routine TEE is probably justified for patients after the Fontan procedure and that routine anticoagulation is probably advisable.
Before accepting the recommendations of Balling and associates, it is important to recognize some significant limitations of their report. As noted above, this is effectively a retrospective review of a selected group of patients who agreed to the TEE procedure. Most patients had undergone their Fontan operation many years before, and therefore only 9 of the 52 had had lateral tunnel–type Fontan procedures. Most had had the old-style right atrium–pulmonary artery anastomosis. Only 7 had a fenestration. Interestingly, none of the patients with a fenestration had detectable thrombus. None of the patients had had a recent thromboembolic event that was symptomatic, and of the 3 patients who had had cerebrovascular events in the past, none had identifiable thrombus by TEE.
With respect to the recommendation regarding anticoagulation, it is important to note that thrombi developed in 7 of these patients despite warfarin sodium (Coumadin) anticoagulation, although the authors would argue that some of these patients at least did not have adequate anticoagulation. The risks of anticoagulation need to be balanced against the morbidity of asymptomatic thrombi detected by routine screening. The risks of routine screening also need to be carefully considered when one notes that nearly 50% of this population required general anesthesia to undergo the TEE procedure.
The technique of TEE is probably quite sensitive to detect intra-atrial thrombi, but the authors have not addressed the specificity of the method. They are now embarking on a study in which magnetic resonance imaging will be used to exclude false positive results, but until the results of that investigation and others are available, it is hard to support the aggressive recommendation for routine TEE and routine anticoagulation in this difficult patient population. Nevertheless, a provocative report such as this article by Balling and associates does highlight the importance once again of urgently completing at least one (and ideally more than one) carefully organized prospective randomized study to address the issue of warfarin sodium versus aspirin versus no anticoagulation in patients after the Fontan procedure. It is important that such studies have sensitive and specific methods for intracardiac thrombus formation, as well as careful prospective assessment for symptoms and signs of thromboembolic events.
12/1/105455 doi:10.1067/mtc.2000.105455
