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Systematic review and meta-analysis of strategies for the diagnosis of suspected pulmonary embolism

BMJ 2005; 331 doi: https://doi.org/10.1136/bmj.331.7511.259 (Published 28 July 2005) Cite this as: BMJ 2005;331:259

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Pulmonary angiography should not be performed in patients with disparate clinical probability of pulmonary embolism and imaging findings

Dear Sir

We would like to comment on the proposed imaging strategies for
excluding pulmonary embolism derived by Roy et al consequent on their meta
-analysis of the strategies for diagnosis of suspected pulmonary embolism
(PE) (1).

A recent systematic review of the clinical validity of a negative
computed tomography pulmonary angiography (CTPA) in patients with
suspected PE showed an overall negative likelihood ratio (NLR) after a
negative CTPA of 0.07 (95% confidence interval [CI], 0.05-0.11) and an
overall negative predictive value (NPV) of 99.4% (95% CI, 98.7%-99.9%)
(2). Recent advances in multidetector CT technology have improved
visualization of sub-segmental pulmonary vessels and multislice CTPA now
has comparable sensitivity to conventional pulmonary angiography (3).
Several outcome studies have demonstrated low morbidity and mortality in
patients not anti-coagulated following a negative CTPA (subsequent PE in
1.1% of patients at 3 months) (4, 5). The 3-month recurrence risk is
comparable to that following negative conventional pulmonary angiography
(0.9%) (6) or normal lung scintigraphy (0.5%) (7). Since the clinical
validity of using CTPA to rule out PE is similar to that of conventional
angiography and both techniques have comparable sensitivities there seems
no logic in subjecting patients with a diagnostic lung perfusion scan or
CTPA (normal or positive) to an additional invasive procedure because of a
disparity between the clinical probability and the imaging findings as the
authors advise.

Furthermore, pulmonary angiography is now infrequently performed and
few radiologists maintain expertise in the technique. For all these
reasons we believe the technique should have only a very limited role in
the evaluation of patients with suspected PE. Readers of this article may
be misled that their patients may still need conventional pulmonary
angiography for definite diagnosis despite evidence to the contrary.

Dr Andrew Scarsbrook (Specialist Registrar in Radiology)

Dr Fergus Gleeson (Consultant Thoracic Radiologist)

Department of Radiology, Churchill Hospital, Oxford, UK

References:

1: Roy PM, Colombet I, Durieux P, Chatellier G, Sors H, Meyer G.
Systematic review and meta-analysis of strategies for the diagnosis of
suspected pulmonary embolism. BMJ. 2005 Jul 30; 331: 259

2: Quiroz R, Kucher N, Zou KH, Kipfmueller F, Costello P, Goldhaber
SZ, Schoepf
UJ. Clinical validity of a negative computed tomography scan in patients
with
suspected pulmonary embolism: a systematic review. JAMA 2005 Apr 27;
293(16): 2012-2017

3: Baile EM, King GG, Muller NL, D'Yachkova Y, Coche EE, Pare PD,
Mayo JR. Spiral computed tomography is comparable to angiography for the
diagnosis of
pulmonary embolism. Am J Respir Crit Care Med 2000; 161: 1010-1015

4: Goodman LR, Lipchik RJ, Kuzo RS, Liu Y, McAuliffe TL, O'Brien DJ.
Subsequent pulmonary embolism: risk after a negative helical CT pulmonary
angiogram - prospective comparison with scintigraphy. Radiology 2000; 215:
535-542

5: Gottsater A, Berg A, Centergard J, Frennby B, Nirhov N, Nyman U.
Clinically suspected pulmonary embolism: is it safe to withhold
anticoagulation after a negative spiral CT? Eur Radiol 2001; 11: 65-72

6: Henry JW, Relyea B, Stein PD. Continuing risk of thromboemboli
among patients with normal pulmonary angiograms. Chest 1995; 107: 1375-
1378

7: Meyerovitz MF, Mannting F, Polak JF, Goldhaber SZ. Frequency of
pulmonary embolism in patients with low-probability lung scan and negative
lower extremity venous ultrasound. Chest 1999; 115: 980-982

Competing interests:
None declared

Competing interests: No competing interests

04 August 2005
Andrew F Scarsbrook
Specialist Registrar in Radiology
Fergus V Gleeson
Department of Radiology, Churchill Hospital, Haedington, Oxford, OX3 7JL