Thromboendarterectomy as Treatment in the Antiphospholipid Syndrome

Suzette W. Peng, MD; Jeanne P. Mitchell, MD

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In This Article

Discussion

PTE was used successfully in this patient with APS and SLE to treat CTEPH, which otherwise carries a poor prognosis. In an English language review of the medical literature, we identified 16 additional cases of patients with APS who underwent thromboendarterectomy for CTEPH.[6,7,8] Most of these patients had primary APS, demonstrated a dramatic improvement in their postoperative hemodynamics, and did not suffer any postoperative complication. Of note, only 1 patient other than this 19-year-old female had an associated connective tissue disorder (SLE) reported, and this patient also had a successful surgical outcome.[7]

APS is classified as primary or secondary depending on whether it occurs in the setting of a defined connective tissue disorder (secondary APS) vs primary (no connective tissue disease present). Interestingly, this patient first presented with primary APS at age 14 that evolved into a clinical picture consistent with SLE at her latter presentation, manifested by hematologic abnormalities and autoantibody production (ANA, SS-B, and SS-A antibodies). The patient also had significant pulmonary hypertension from chronic pulmonary embolisms.

If a patient survives an acute pulmonary embolus, they may have any of the following outcomes: (1) complete anatomic and hemodynamic resolution, (2) partial resolution with normal clinical and hemodynamic status, or (3) partial resolution with progression to pulmonary hypertension. In the case of our patient, the thrombi did not dissolve but instead organized to form fibrous masses that further occluded the pulmonary arteries and resulted in pulmonary hypertension. Our patient had evidence of a calcified thrombus and perfusion defects that were unchanged from her prior scan years earlier, indicating only partial resolution of an old thrombus.

Pulmonary hypertension resulting from chronic thromboembolic disease can be defined as a mean resting pulmonary artery pressure greater than 25 mm Hg obtained during right heart catheterization with a mean pulmonary wedge pressure below 12 mm Hg, at least 1 segmental or larger perfusion defect, and an angiographic pattern of chronic thromboembolic pulmonary obstruction.[6] The prognosis of CTEPH is poor and has a 5-year survival rate of 30% when the mean pulmonary artery pressure exceeds 40 mm Hg, and is 10% in patients with PASPs exceeding 50 mm Hg.[9] While medical management exists, it has no significant impact on survival.

Pulmonary thromboendarterectomy is a relatively new approach to normalizing the elevated pulmonary vascular resistance that may result from a chronic, adsorbed thrombus and is feasible in patients who have thrombotic obstruction at the level of the large, elastic pulmonary arteries as was present in this patient. Lung transplantation is the only other procedure that offers hope for cure. In 2003, only about 2500 PTEs had been performed worldwide.[4] They are mainly performed at specialized centers such as the University of California, San Diego, where this patient was referred. The surgery itself is different from an embolectomy and involves dissection of the thrombus as well as part of the intimal layer of the effected pulmonary artery.[10] The surgery offers increased survival (>75% at 5 years vs 40% at 4 years for lung transplantation), function, and quality of life[4,11,12,13,14], but the 30-day mortality associated with surgery ranges from 4.4% to 18%.[4,11,12,13] Patients meeting the criteria for surgery should be referred to centers familiar with the procedure in order to maximize success with the least risk.

There are limited data on predictors of success for the surgery and specific indications. Nevertheless, the American College of Chest Physicians (ACCP) recently published Practice Guidelines including selection criteria for surgery.[10] They identified the following 4 criteria: (1) New York Heart Association Class III or IV symptoms; (2) a pulmonary vascular resistance of 300 dynes·s-1·cm-5; (3) surgically accessible thrombus defined as thrombus in the main, lobar, or segmental pulmonary arteries; and (4) no significant comorbidities (especially severe underlying lung disease).[10]

PASP was not used as a selection criteria, as the available data suggest that there is no need to perform surgery just because of an elevated PASP in the absence of significant symptoms. However, significantly high levels of PASP such as that seen in our patient may indicate a need for surgery to avoid potential long-term effects of pulmonary hypertension. A recent case-control study demonstrated that patients with very high PASPs (>100 mm Hg) can also undergo the procedure with good outcomes.[15] In fact, the mortality was 6% lower in the patients with PASPs > 100 mm Hg, and the same group had larger reductions in PASP. Further studies are warranted to determine the most appropriate indications for PTE.

It is important to note that PTE patients with APS and a history of venous thromboembolism still require lifelong anticoagulation given the high rates of recurrence. A recent systematic review recommended warfarin with a goal INR of 2.0-3.0 as initial treatment.[1] If a patient has a recurrent event, then the recommendations are less clear. The first step is to ensure that the patient is reaching a therapeutic range on warfarin. If the range is therapeutic but has failed in the patient, then one option is to increase the INR target range to 2.5-3.5 or 3.0-4.0. Some studies suggest that switching the patient to low-molecular-weight heparin (LMWH) alone or adding clopidogrel or aspirin to warfarin may be successful.[1]

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