Pulmonary embolism commonly occurred among patients hospitalized for syncope, according to study results published in The New England Journal of Medicine.
“Syncope is defined as a transient loss of consciousness that has a rapid onset, short duration and spontaneous resolution and is believed to be caused by temporary cerebral hypoperfusion,” Paolo Prandoni, MD, PhD, of the vascular medicine unit of the department of cardiovascular sciences at University of Padua, Italy, and colleagues wrote. “Although PE is included in the differential diagnosis of syncope in most textbooks, rigorously designed studies to determine the prevalence of pulmonary embolism among patients hospitalized for syncope are lacking.”
Prandoni and colleagues conducted a cross-sectional study of patients hospitalized for a first episode of syncope at 11 hospitals in Italy. The researchers completed a diagnostic workup for PE in these patients within 48 hours of hospital admission, regardless of alternate explanations for syncope.
Patients considered at low risk for PE based on a low pretest clinical probability score — comprised of a negative D-dimer assay and Wells score — received no further diagnostic screening. The remaining patients received a CT pulmonary angiography or ventilation–perfusion lung scan.
The study included data from 560 patients. The median age of patients was 80 years (interquartile range, 72-85) and 77.7% were aged 70 years or older.
The researchers ruled out PE in 58.9% (n = 330) of the patient population due to low pretest clinical probability and negative D-dimer test results.
Among the remaining patients, 58.7% (n = 135) had a positive D-dimer result only, 1.3% (n = 3) had a high pretest clinical probability score only, and 40% (n = 92) had both.
A total of 229 patients underwent additional screening by CT (n = 180) or ventilation–perfusion lung scan (n = 49).
Ninety-six patients received a diagnosis of PE (CT, n = 72; ventilation–perfusion lung scan, n = 24). One additional deceased patient had a PE confirmed by autopsy.
PE prevalence was 17.3% (95% CI, 14.2-20.5) in the entire cohort and 42.2% (95% CI, 35.8-48.6) among screened patients.
Forty-eight patients with confirmed PE exhibited thrombosis risk factors, including active cancer (n = 19), infectious disease (n = 12), prolonged immobility (n = 10), and recent surgery or trauma (n = 7).
Thirty patients (41.7%) diagnosed with PE by CT scan had the most proximal location of the embolus in a main pulmonary artery; the remaining patients had a location of embolus in a lobar artery (n = 18), a segmental artery (n = 19) or a subsegmental artery (n = 5).
Among patients diagnosed by ventilation–perfusion lung scan, four patients had a perfusion defect involving more than 50% of the area of both lungs, and eight patients had a perfusion defect comprising 26% to 50% of both lungs.
Fifty-two patients (25.4%; 95% CI, 19.4-31.3) with PE had a syncope of undetermined origin and 45 patients (12.7%; 95% CI, 9.2-16.1) had a syncope with a potential alternative explanation.
Patients with PE had a higher prevalence of 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 venous thromboembolism (11.3% vs. 4.3%), or active cancer (19.9% vs. 9.9%).
The researchers acknowledged limitations of their findings. Because the study solely included hospitalized patients, the researchers could not capture data from patients treated in ambulatory settings or in the ED without hospitalization.
Further, the study did not require a specific workup for the diagnosis of syncope; diagnostic variations may have influenced study data.
“The unexpectedly high prevalence of PE among our patients with syncope contrasts with that reported elsewhere,” Prandoni and colleagues 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% — approximately one in every six patients.” – by Cameron Kelsall
Disclosure: Prandoni reports no relevant financial disclosures. Please see the full study for a list of all other researchers’ relevant financial disclosures.