Subsegmental pulmonary embolism may not be clinically relevant

31 August 2010

MedWire News: Multiple-detectors computed tomographic pulmonary angiography (CTPA) increases the proportion of patients diagnosed with subsegmental pulmonary embolism (PE) without changing the 3-month risk for venous thromboembolism (VTE), suggesting that the disease may not be clinically relevant, researchers report.

Grégoire Le Gal (Centre Hospitalier Universitaire de la Cavale Blanche, Brest, France) and colleagues explain that multiple-detectors CTPA is known to have a higher sensitivity for PE within the subsegmental pulmonary arteries compared with single-detector CTPA, but the clinical significance of subsegmental PE is unclear.

The team therefore carried out a systematic review and meta-analysis to compare the incidence of subsegmental PE diagnosed with single- and multiple-detectors CTPA and determine the subsequent VTE risk associated with a negative CTPA result.

A systematic search of MEDLINE, EMBASE and the Cochrane Register of Controlled Trials identified 22 articles (20 prospective cohort studies and two randomized controlled trials) that included patients with suspected PE who underwent a CTPA and reported the rate of subsegmental PE.

In total, 2657 patients with confirmed PE were included in the analyses. Of these, 1123 and 1534 patients underwent single- and multiple-detectors CTPA, respectively.

The researchers report a subsegmental PE diagnosis rate of 4.7% and 9.4% in patients that underwent single and multiple-detector CTPA, respectively.

The 3-month VTE risk in patients with suspected PE that was left untreated based on a diagnostic algorithm including a negative CTPA was 0.9% and 1.1% for single- and multiple-detectors CTPA, respectively.

Le Gal and co-authors remark that because the use of multiple-detector in preference to single-detector CTPA will increase the incidence of subsegmental PE diagnosis, an increase in the number of patients being exposed to anticoagulation therapy is likely.

Since approximately 2% of patients receiving anticoagulation will experience a major bleeding episode, further prospective studies are required to assess the risk:benefit ratio of such treatment in patients with subsegmental PE, they conclude in the Journal of Thrombosis and Haemostasis.

MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010

J Thromb Haemost 2010; 8: 1716-1722