Clinical Features of Patients With Pulmonary Embolism and a Negative PERC Rule Result

Abstract

We write with reference to the case report by Hennessey et al1Hennessey A. Setyono D.A. Lau W.B. et al.A patient with a large pulmonary saddle embolus eluding both clinical gestalt and validated decision rules.Ann Emerg Med. 2012; 59: 521-523Abstract Full Text Full Text PDF PubMed Scopus (10) Google Scholar of a patient with a radiographically large pulmonary embolism that was represented as a case of a false-negative result of the pulmonary embolism rule-out criteria (PERC). The authors concluded that “further characterization of the types of pulmonary embolism missed by PERC and their associated outcomes would be desirable.” In an accompanying editorial, Green and Yealy2Green S.M. Yealy D.M. Right-sizing testing for pulmonary embolism: recognizing the risks of detecting any clot.Ann Emerg Med. 2012; 59: 524-526Abstract Full Text Full Text PDF PubMed Scopus (9) Google Scholar warned, “Case reports often highlight anomalies that alone should not necessarily change practice or thinking.” We agree that a case report provides only a pinhole view of a much broader clinical landscape. To offer a larger and more scientifically valid view of the clinical features of patients with a negative PERC rule result but with pulmonary embolism diagnosed, we performed a secondary analysis of a prospectively collected registry of 1,880 emergency department (ED) patients receiving a diagnosis of acute pulmonary embolism.3Pollack C.V. Schreiber D. Goldhaber S.Z. et al.Clinical characteristics, management, and outcomes of patients diagnosed with acute pulmonary embolism in the emergency department: Initial Report of EMPEROR (Multicenter Emergency Medicine Pulmonary Embolism in the Real World Registry).J Am Coll Cardiol. 2011; 57: 700-706Abstract Full Text Full Text PDF PubMed Scopus (337) Google Scholar Because these patients were enrolled after the diagnosis of pulmonary embolism was established, we lack a reliable assessment of gestalt suspicion of pulmonary embolism. Accordingly, we present results of patients who tested negative for the 8 objective criteria of PERC (younger than 50 years, pulse <100 beats/min, SaO2 >94%, no previous venous thromboembolism, no recent surgery, no unilateral limb swelling, no hemoptysis, and no estrogen use). Of the 1,880 patients with pulmonary embolism in the registry, 114 (6.1%; 95% confidence interval [CI] 5.0% to 7.2%) had negative results for all 8 objective factors of the PERC rule. The Table compares the proportions of 26 clinical variables between PERC negative and PERC positive. Pleuritic chest pain, pregnancy, and postpartum status were the only 3 variables that demonstrated a true difference in their proportions and were more frequent in the PERC-negative group. PERC-negative patients also had a lower frequency of respiratory distress and right ventricular strain; we did not collect data about size of pulmonary embolism on computed tomography (CT) scan. The only significant difference we observed in outcomes was that objective PERC-negative patients had a lower all-cause mortality rate at 30 days: 0 of 114 (0%) versus 108 of 1,776 (5.7%) (95% CI for 5.7% difference 2.5% to 6.9%).TableComparison of clinical features based on PERC status, using the 8 objective criteria only.⁎Using only the 8 objective factors of the PERC rule.Clinical Features at PresentationPERC NegativePERC PositiveDifference, %95% CI for Differencen of 114%n of 1,766%Pleuritic chest pain⁎Using only the 8 objective factors of the PERC rule.645667638184.4 to 24.2Respiratory distress7630217−11−15.6 to −5.7Evidence of RV strain†Elevated serum troponin level, brain natriuretic peptide or NT–pro-brain natriuretic peptide, or echocardiography demonstrating RV hypokinesis.171545226−11−17.5 to −3.2Known coronary artery disease5428316−12−14.4 to −4.6Recent hospitalization‡Past 6 months.111043725−15−20.4 to −8.2Dyspnea at rest464089651−10−19.1 to 0.5Current malignancy‡Past 6 months.151340423−10−14.6 to −0.4Substernal chest pain2421261156−0.9 to 15.3Generalized immobility >48 h10920812−3−8.8 to 2Diabetes131127516−4−9.7 to 3.2Chronic lung disease§Chronic obstructive lung disease, lung fibrosis, sarcoidosis, asbestosis, or other destructive process.6518811−5−14 to 3.5Heart failure651358−2−6.5 to 2.2Male sex474184048−6−13 to 6.7Malignancy in remission221066−4−5.9 to 1.1Pregnancy549141.0 to 9.3Postpartum∥Past month.4412130.8 to 9.2Diaphoresis761267−1−6.1 to 2.7Do not resuscitate11624−3−3.8 to 2Systolic blood pressure <90 mm Hg11624−3−3.8 to 2Body mass index >40 kg/m2292547627−2−9.7 to 7.5Syncope in presenting syndrome769651−2.2 to 8.4Known thrombophilia656442−1.0 to 8.9Sickle cell disease221011−0.1 to 6.4Cough without hemoptysis2623404230−6.4 to 10.6Family history of DVT or PE141214384−3.8 to 8Inherited clotting problem00241−1−2.0 to 2.4Indwelling venous catheter878352−2.9 to 6.4DVT, Deep venous thrombosis; PE, pulmonary embolism; PERC, pulmonary embolism rule out criteria; RV, right ventricle. Using only the 8 objective factors of the PERC rule.† Elevated serum troponin level, brain natriuretic peptide or NT–pro-brain natriuretic peptide, or echocardiography demonstrating RV hypokinesis.‡ Past 6 months.§ Chronic obstructive lung disease, lung fibrosis, sarcoidosis, asbestosis, or other destructive process.∥ Past month. Open table in a new tab DVT, Deep venous thrombosis; PE, pulmonary embolism; PERC, pulmonary embolism rule out criteria; RV, right ventricle. We interpret these data as having several implications. First, we are reminded that pleuritic chest pain significantly increases the probability of a filling defect on CT scan diagnostic for pulmonary embolism in ED patients with suspected pulmonary embolism.4Courtney D.M. Kline J.A. Kabrhel C. et al.Clinical features from the history and physical examination that predict the presence or absence of pulmonary embolism in symptomatic emergency department patients: results of a prospective, multicenter study.Ann Emerg Med. 2010; 55: 305-315Abstract Full Text Full Text PDF Scopus (53) Google Scholar Assuming that pleuritic chest pain marks the presence of lung ischemia, pulmonary infarction may increase the risk of a false-negative PERC result. Patients with pulmonary infarction tend to have fewer and smaller pulmonary arterial filling defects on pulmonary angiography, higher blood oxygenation, and lower pulse rate than patients with pulmonary embolism and no pulmonary infarction.5Stein P.D. Henry J.W. Clinical characteristics of patients with acute pulmonary embolism stratified according to their presenting syndromes.Chest. 1997; 112: 974-979Crossref PubMed Scopus (208) Google Scholar PERC-negative pulmonary embolism patients tended to have a more benign clinical course than PERC-positive patients. In contrast to the case report by Hennessey et al,1Hennessey A. Setyono D.A. Lau W.B. et al.A patient with a large pulmonary saddle embolus eluding both clinical gestalt and validated decision rules.Ann Emerg Med. 2012; 59: 521-523Abstract Full Text Full Text PDF PubMed Scopus (10) Google Scholar data from this large sample suggest that PERC is more likely to miss small, distal pulmonary embolism. The data also suggest that PERC should not be used in isolation to rule out pulmonary embolism in patients with pregnancy and postpartum status. A Patient With a Large Pulmonary Saddle Embolus Eluding Both Clinical Gestalt and Validated Decision RulesAnnals of Emergency MedicineVol. 59Issue 6PreviewWe report a patient with chest pain who was classified as having low risk for pulmonary embolism with clinical gestalt and accepted clinical decision rules. An inadvertently ordered D-dimer and abnormal result, however, led to the identification of a large saddle embolus. This case illustrates the fallibility of even well-validated decision aids and that an embolism missed by these tools is not necessarily low risk or indicative of a low clot burden. Full-Text PDF In replyAnnals of Emergency MedicineVol. 61Issue 1PreviewIn response to the rebuttal by Kline et al,1 we agree that a case report provides limited insight and, as previously stated, does not suggest “a failure of a validated decision rules such as the PERC [pulmonary embolism rule-out criteria].”2 In our discussion, we questioned the relationship between false-negative PERC status, clot burden, and outcomes. Kline et al1 attempt to offer a more “scientifically valid” look at this question than our case report but go on to reference a study in which PERC was retrospectively applied to a cohort of patients “that lack[ed] a reliable assessment of gestalt suspicion of [pulmonary embolism]” and in whom clot burden was not measured. Full-Text PDF