Occult Chronic Thromboembolic Disease in Patients Presenting for Surgical Pulmonary Embolectomy

Pulmonary embolism is a significant cause of morbidity and mortality. An important subpopulation of patients presenting with acute pulmonary embolism have concurrent undiagnosed chronic thromboembolic disease. We sought to further characterize this subpopulation, specifically in a cohort of patients referred for surgical pulmonary embolectomy.

A retrospective review of all patients requiring surgical pulmonary embolectomy at a single center (2013-2017) was performed. Chart review and blinded examination of presenting computed tomographic pulmonary angiograms were done to identify clinical and radiographic features associated with acute on chronic disease. A predictive tool utilizing readily accessible variables was then constructed for risk stratification.

A total of 90 patients were identified for analysis; 34 were treated by specifically trained pulmonary thromboendarterectomy surgeons. Twelve patients in the subgroup treated by pulmonary thromboendarterectomy surgeons were found to have acute on chronic disease confirmed by intraoperative endarterectomized specimen. On univariate analysis, degree of pulmonary artery and inferior vena cava dilation and duration of respiratory symptoms were statistically significant variables. Severe right ventricular hypertrophy, elevation in N-terminal pro-B-type natriuretic peptide, and unprovoked etiology were also associated with acute on chronic disease. A predictive tool weighing the presence of these features was created allowing for stratification into low-, moderate-, and high-risk patients. The positive predictive value of a high-risk score was 100%.

In this cohort, the prevalence of acute on chronic thromboembolic disease was greater than 1 in 3. Readily available clinical and radiographic features were used to create a predictive tool for risk stratification.