CLINICAL NEWS
Nearly One in Six Patients Hospitalized for First-Time Syncope Have Pulmonary Embolism
The prevalence of pulmonary embolism ( PE ) among hospitalized patients with syncope is not well understood , and international guidelines – such as the European Society of Cardiology and the American Heart Association – do not recommend a diagnostic workup for PE in this patient population . According to a crosssectional study led by Paolo Prandoni , MD , PhD , of the Department of Cardiovascular Sciences in the Vascular Medicine Unit at the University of Padua in Italy , and researchers , which was published in the New England Journal of Medicine , the prevalence of PE in patients hospitalized for first-time syncope was 17.3 percent ( 95 % CI 14.2-20.5 ), or approximately one in six patients .
“ A diagnostic workup for PE should be strongly encouraged in all patients admitted with a first episode of syncope ( provided they are not anticoagulated ), including those in whom there is an apparent explanation for the episode of syncope ,” Dr . Prandoni told ASH Clinical News . “ As PE is a serious and potentially lethal complication that can be treated effectively and safely with the available antithrombotic drugs , its prompt detection is crucial .”
“Diagnostic workup for PE should be strongly encouraged in all patients admitted with a first episode of syncope ( provided they are not anticoagulated ).”
— PAOLO PRANDONI , MD , PhD
The study included adult patients who were hospitalized for a first episode of syncope ( defined as a transient loss of consciousness with rapid onset , short duration [ i . e ., < 1 minute ], and spontaneous resolution , after obvious causes such as epileptic seizure , stroke , and head trauma have been ruled out ).
All patients who were admitted to a medical ward after visiting the emergency department at one of 11 participating general hospitals in Italy ( 2 academic and 9 non-academic ) were eligible for inclusion , provided they did not have a previous episode of syncope , were not receiving anticoagulation therapy , and were not pregnant . Patients visited the hospital for the following reasons :
• trauma related to falls
• severe coexisting conditions
• failure to identify an explanation for the syncope
• high probability of cardiac syncope on the basis of the Evaluation of Guidelines in Syncope Study score
Between March 2012 and October 2014 , 2,584 patients were admitted to the emergency department for syncope . The final patient cohort was 560 , with a median age of 80 years ( range = 72-85 years ). All patients underwent an assessment within 48 hours of being admitted to the hospital , regardless of alternate explanations for syncope . Assessment included a medical history , including the presence of prodromal symptoms of autonomic activation , presence of known cardiac disease , recent bleeding , causes of volume depletion or venous pooling , and recent exposure to new or stronger hypotensive drugs or drugs that could cause bradycardia or tachycardia . Patient were interviewed about symptoms ( pain and swelling ) in the legs and presence of risk factors for venous thromboembolism ( VTE ), ongoing hormonal treatment , prolonged immobilization of ≥1 week , active cancer , and history of VTE . Patients were evaluated for the presence of arrhythmias , tachycardia ( i . e ., heart rate > 100 beats / min ), valvular heart disease , hypotension ( i . e ., systolic blood pressure < 110 mm Hg ), autonomic dysfunction , tachypnea ( i . e ., respiratory rate > 20 breaths / min ), and swelling or redness of the legs .
Patients also underwent chest radiography , electrocardiography , arterial blood gas testing , and routine blood testing that included a D-dimer assay .
Patients considered at low risk for PE based on a low pretest clinical probability score and a negative D-dimer assay received no further diagnostic screening , and PE was not assumed . The remaining patients received a CT pulmonary angiography or ventilation – perfusion lung scan .
Clinical evidence suggested that PE was not the reason for syncope in 63.4 percent of patients ( n = 355 / 560 ), and PE diagnosis was ruled out due to low pretest probability scores and a negative D-dimer assay in 58.9 percent of patients ( n = 330 / 560 ).
Among the 230 remaining patients , 58.7 percent ( n = 135 ) had a positive D-dimer assay , 1.3 percent ( n = 3 ) had a high pretest probability , and 40 percent ( n = 92 ) had both .
A total of 229 patients underwent further diagnostic screening with CT ( n = 180 ) or ventilation – perfusion lung scans ( n = 49 ).
Ninety-six of these patients were diagnosed with PE : 72 patients underwent CT scans and 24 underwent ventilation – perfusion lung scan . PE was identified as the cause of death in one patient ( confirmed by autopsy ).
“ The unexpectedly high prevalence of PE among
our patients with syncope contrasts with that reported elsewhere ,” Dr . Prandoni and authors wrote . “ Among patients who were hospitalized for a first episode of syncope and who were not receiving anticoagulation therapy , PE was confirmed in 17.3 percent [ of the entire cohort ], or approximately one in every six patients .” Prevalence of PE among screened patients was 42.2 percent ( 95 % CI 35.8-48.6 ).
“ Although the prevalence of PE was highest among patients who presented with syncope of undetermined origin ( 25.4 % of patients ), almost 13 percent of patients diagnosed with PE had potential alternative explanations for syncope ,” the authors wrote .
Dr . Prandoni and authors also observed that patients with PE had a higher prevalence of the following conditions , compared with those without PE : tachypnea ( 45.4 % vs . 7.1 %), tachycardia ( 33 % vs . 16.2 %), hypotension ( 36.1 % vs . 22.9 %), clinical signs or symptoms of deep-vein thrombosis ( 40.2 % vs . 4.5 %), previous VTE ( 11.3 % vs . 4.3 %), and active cancer ( 19.6 % vs . 9.9 %). In addition , 24.7 percent of patients with PE ( n = 24 / 97 ) had no clinical manifestation of the diagnosis .
“ Whenever PE cannot be excluded , therapeutic doses of either low-molecular-weight heparin or fondaparinux should be promptly given while awaiting the results of objective instrumental tests unless they are contraindicated ,” Dr . Prandoni advised . “ This approach is potentially life-saving .”
Limitations of the study include its restriction to only include patients in the hospital setting . In addition , diagnostic imaging for PE was only performed in patients who had an elevated D-dimer or high pretest clinical probability of PE . The study also did not require a specific workup for syncope diagnosis , so diagnostic variations may have influenced the findings . ●
REFERENCE
Prandoni P , Lensing AWA , Prins MH , et al . Prevalence of pulmonary embolism among patients hospitalized for syncope . N Engl J Med . 2016 ; 375:1524-31 .
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