Assessing the role of Computed Tomography Pulmonary Angiogram in diagnosing right heart strain related to acute pulmonary embolism

Right heart strain (RHS) is a commonly occurring and significant complication of acute pulmonary embolism (PE). CTPA images often suggest pulmonary hypertension; however, diagnostic echocardiography is not always immediately available to confirm this. In this study, we assessed how accurately Computed Tomography Pulmonary Angiography (CTPA), troponin, and NT-proBNP predict evidence of RHS in patients with acute PE, compared with transthoracic echocardiography (TTE).

A total of 656 patients had CTPAs performed over 6 months at a tertiary university hospital. Studies positive for PE were then separated into those with and without reported CTPA evidence of RHS. Patients’ TTE, troponin-T, NT-proBNP, and D-dimer results were assessed, and potential relationships were explored.

About 128 (19.5%) studies were positive for acute PE, and 25 patients with RHS on CTPA had TTEs, with 16 showing evidence of RHS. A total of 39 patients with PEs and no CTPA-reported RHS had TTEs, with 7 suggesting RHS. CTPAs showed a 69.6% sensitivity and 78.0% specificity in predicting RHS. NT-pro-BNP (cut-off 300pg/ml) and troponin-T (cut-off 34ng/L) showed higher sensitivity, 92.9% and 75%, respectively, and lower specificity, 33.3% and 58%, respectively, than CTPA. 329/656 (50%) had an alternative explanation for symptoms on CTPA, meaning only 30.5% of patients had no explanation for symptoms.

While an accessible and useful test, CTPA is not as reliable in predicting RHS in patients with acute PE as TTE.

Patients diagnosed with a clinically significant PE should be considered for TTE regardless of whether or not RHS is evident on CTPA.