Pulmonary embolism: risk-stratify, anticoagulate, escalate — the AU GP approach

Pulmonary embolism (PE) is obstruction of the pulmonary arterial circulation by thrombus, most commonly arising from a deep vein thrombosis (DVT) in the lower limbs or pelvis. Australian incidence is approximately 1–2 per 1,000 adults per year, and the condition becomes more common with ageing. Mortality exceeds 25% without treatment; in correctly anticoagulated stable patients it falls to 3–10%.

PE sits on a wide clinical spectrum — from incidentally detected sub-segmental clot on a chest CT performed for another reason, to saddle embolus straddling the main pulmonary artery bifurcation causing rapid cardiovascular collapse. Most presentations lie between these extremes: breathless, mildly hypoxic, tachycardic patients who look unwell but remain haemodynamically stable.

The GP role is central at three stages: suspecting PE when clinical features are present; risk-stratifying to determine the need for imaging; and initiating anticoagulation promptly once PE is confirmed. The Thrombosis and Haemostasis Society of Australia and New Zealand (THANZ), eTG, and the ESC 2019 PE guideline all endorse direct oral anticoagulants (DOACs) as first-line treatment for most stable PE. Massive PE — defined by haemodynamic instability — is a 000 emergency.

A. Core clinical — the AU general-practice framework

Risk factors: Virchow’s triad in general practice

Risk factors fall into three categories:

Stasis: Recent major surgery (especially orthopaedic or abdominal pelvic), hospitalisation with reduced mobility exceeding 3 days, long-haul travel over 4 hours, plaster cast immobilisation, paralytic stroke.

Hypercoagulability: Active malignancy — the most common acquired risk factor (~20% of all PE; raises risk 3–10-fold). Combined hormonal contraceptives (oestrogen-containing pill, patch, or vaginal ring) raise risk 3–5-fold. Pregnancy and the post-partum period carry a 5-fold elevation. Inherited thrombophilias (Factor V Leiden, prothrombin G20210A, antithrombin deficiency, protein C or S deficiency, antiphospholipid syndrome) confer additional risk. Prior VTE is itself one of the strongest individual risk factors for recurrence.

Endothelial injury: Surgery, trauma, central venous catheters.

Clinical features

Symptoms are highly variable. According to the ESC 2019 guideline, the most common presenting features in confirmed PE are:

• Dyspnoea (~73%) — often sudden onset; ranges from mild exertional to severe at rest
• Pleuritic chest pain (~44%) — sharp, worsened by inspiration; indicates peripheral infarction
• Cough (~35%) — usually non-productive
• Haemoptysis (~13%) — small volumes; massive haemoptysis suggests another diagnosis
• Syncope or presyncope (~7%) — indicates haemodynamic compromise; must prompt 000 consideration

Examination may reveal tachycardia, tachypnoea, and hypoxia. Unilateral leg swelling, calf tenderness, or a palpable cord indicates DVT in approximately 30% of confirmed PE cases. Signs of acute right ventricular (RV) failure — loud P2, raised jugular venous pressure, RV heave — indicate haemodynamic compromise.

Severity classification

The ESC 2019 guideline classifies PE by haemodynamic status and markers of RV dysfunction:

• High-risk (massive) — cardiac arrest, sustained SBP below 90 mmHg, or obstructive shock; mortality 30–60%
• Intermediate-high risk — haemodynamically stable but both elevated troponin and RV dysfunction on imaging or echocardiogram
• Intermediate-low risk — stable, with only one of the above markers
• Low-risk — simplified PESI score of 0; no RV dysfunction; mortality below 1%

Investigations and risk stratification

12-lead ECG is performed in every patient with suspected PE. Sinus tachycardia is most common; the classic S1Q3T3 pattern is specific but occurs in only ~10%. Right axis deviation and T-wave inversions across V1–V4 indicate RV strain.

The Wells PE score (MDCalc) uses 7 clinical variables to assign pre-test probability. In the two-level version: PE likely (>4 points) or PE unlikely (≤4). High probability — proceed directly to CTPA without D-dimer.

The PERC rule (Kline 2008) applies only to low-probability patients: if all 8 criteria are negative (age under 50, HR below 100, SpO₂ ≥95%, no unilateral leg swelling, no haemoptysis, no recent surgery or trauma, no prior VTE, no oestrogen use), no further PE testing is required.

D-dimer with an age-adjusted threshold — age × 10 µg/L in patients over 50 — was validated in the ADJUST-PE trial (JAMA 2014). This increases specificity from approximately 34% to 63% in older patients without sacrificing sensitivity, reducing unnecessary CTPA. A negative D-dimer at the age-adjusted threshold with low or intermediate pre-test probability safely excludes PE without imaging.

CT pulmonary angiography (CTPA) is the gold standard with sensitivity and specificity exceeding 95%. V/Q scanning is the alternative when CTPA is contraindicated: contrast allergy, significant renal impairment, or pregnancy — particularly in the first trimester when minimising foetal radiation dose is important.

B. Evidence appraisal — DOACs, age-adjusted D-dimer, and outpatient management

DOAC superiority over warfarin

Multiple large randomised controlled trials have confirmed DOACs as first-line treatment for acute PE. The AMPLIFY trial (NEJM 2013) demonstrated apixaban was non-inferior to warfarin for recurrent VTE with significantly lower major bleeding. The EINSTEIN-PE trial (NEJM 2012) showed rivaroxaban was similarly effective with a lower rate of major bleeding. Both allow direct initiation without parenteral anticoagulation bridging, simplifying outpatient management considerably.

Dabigatran and edoxaban require 5–10 days of low-molecular-weight heparin (LMWH) lead-in before switching to oral therapy — less convenient for outpatient initiation. Warfarin with INR monitoring (target 2–3) remains appropriate when DOACs are contraindicated or not tolerated.

Cancer-associated PE

DOAC therapy is now preferred over LMWH for cancer-associated PE. The HOKUSAI-VTE Cancer trial (NEJM 2018) and CARAVAGGIO trial (NEJM 2020) both showed DOACs were non-inferior to enoxaparin for recurrent VTE with similar or lower bleeding rates. Apixaban is favoured for gastrointestinal and genitourinary cancers where mucosal bleeding risk is relevant. In pregnancy, enoxaparin remains the anticoagulant of choice — DOACs cross the placenta and are contraindicated.

Outpatient management

The Hestia criteria and simplified PESI score identify patients suitable for outpatient treatment. THANZ supports outpatient management in appropriately selected low-risk patients with stable haemodynamics, adequate oxygen saturation, no major comorbidities or bleeding risk, and reliable home support. DOAC initiation with close general practice follow-up at 1 week is the standard community pathway.

C. Treatment — anticoagulation, duration, and recurrence prevention

Initiating treatment

Per eTG and the Australian Medicines Handbook (AMH), DOAC choice depends on the clinical situation:

Agent	Starting dose	Maintenance
Apixaban (Eliquis)	10 mg twice daily × 7 days	5 mg twice daily
Rivaroxaban (Xarelto)	15 mg twice daily × 21 days	20 mg daily with evening meal
Dabigatran (Pradaxa)	After 5–10 days LMWH	150 mg twice daily
Edoxaban (Lixiana)	After 5–10 days LMWH	60 mg daily

Significant drug interactions include St John’s Wort (induces DOAC metabolism, reducing efficacy) and grapefruit (inhibits rivaroxaban metabolism in high amounts). Always advise patients to declare anticoagulant therapy when starting any new prescription or over-the-counter medication, and to avoid ibuprofen and other NSAIDs.

Treatment duration

• Provoked PE (surgery, hospitalisation, or fracture as transient risk factor) — 3 months
• Unprovoked PE — minimum 3 months; review extended therapy; recurrence risk without ongoing anticoagulation is ~30% at 5 years
• Cancer-associated PE — continue while cancer is active
• Recurrent VTE or hereditary thrombophilia — typically lifelong after haematology assessment
• Antiphospholipid syndrome (triple-positive APS) — lifelong anticoagulation; warfarin preferred over DOACs in confirmed APS

Safety netting for anticoagulated patients

Minor bruising and prolonged bleeding from small cuts are expected. Patients should seek urgent care or call 000 for: vomiting blood, black or tarry stools, blood in urine, severe or sudden headache, large unexplained bruising, or any collapse. Document this discussion in the medical record at initiation of therapy.

D. Australian operations

MBS pathways

The following Medicare Benefits Schedule items apply to PE workup and follow-up in general practice (current schedules at MBS Online):

• GP consultations: items 23, 36, 44
• ECG: item 11707
• CTPA: items 56301/56307
• V/Q scan: items 61359/61364
• Echocardiogram (specialist-ordered): item 55113
• Compression ultrasound legs (specialist): item 55274
• GPCCMP for chronic anticoagulation management: items 965/967

PBS and anticoagulant access

Under the Pharmaceutical Benefits Scheme, apixaban, rivaroxaban, dabigatran, and edoxaban all require Authority for PE treatment. Enoxaparin (Clexane) is Authority Required for acute VTE treatment. Warfarin is on the General Schedule. Reversal agents — idarucizumab (Praxbind) for dabigatran reversal, andexanet alfa for anti-Xa reversal — have restricted access; discuss with haematology when needed. The AMH should be consulted for current PBS criteria before prescribing.

Specialist referral pathways

THANZ supports shared GP–haematology care for complex cases. All unprovoked PE warrants haematology referral for thrombophilia assessment after the acute treatment period is established. Recurrent VTE, cancer-associated PE with complex anticoagulation decisions, and confirmed antiphospholipid syndrome benefit from specialist co-management. All suspected massive PE requires immediate 000 transfer or emergency department referral.

Aboriginal and Torres Strait Islander considerations

The RACGP 715 Health Assessment framework and Closing the Gap PBS co-payment reduce cost barriers to DOAC access for First Nations patients. Coordinate with Aboriginal Community Controlled Health Organisations (ACCHOs) when managing ongoing anticoagulation in community settings.

E. Special populations

Pregnancy

LMWH (enoxaparin) is the standard anticoagulant throughout pregnancy and for at least 6 weeks post-partum. DOACs cross the placenta and are not appropriate in pregnancy. Warfarin is teratogenic in the first trimester. V/Q scanning is preferred over CTPA in first-trimester pregnancy where possible — CTPA delivers less foetal radiation but higher breast tissue dose; both modalities are used when clinical need is clear. Always co-manage with obstetrics and haematology in a tertiary centre.

Older adults

Renal impairment reduces DOAC clearance — creatinine clearance below 30 mL/min is a contraindication to most agents (check individual product criteria with AMH). Bleeding risk increases substantially in older adults, particularly with concurrent antiplatelet therapy and history of falls. Weigh recurrence risk against bleeding risk carefully. NSAIDs are to be avoided. Falls prevention and medication review are integral components of ongoing management.

Cancer patients

DOAC therapy is preferred over LMWH for most cancer-associated PE as demonstrated by HOKUSAI-VTE Cancer and CARAVAGGIO. Active gastrointestinal or genitourinary malignancy with mucosal involvement may carry higher bleeding risk — enoxaparin remains reasonable in those settings. Anticoagulation continues for as long as cancer is active. Regular review for thrombocytopenia and bleeding complications is essential, particularly during chemotherapy cycles.

Young adults with unprovoked PE

Patients under 50 with first unprovoked PE and no clear transient risk factor warrant thrombophilia testing and discussion about extended anticoagulation after the acute phase. Women should avoid combined hormonal contraception going forward — long-acting reversible contraception or progestogen-only options are recommended alternatives.

When to escalate

Call 000 immediately for: sustained systolic BP below 90 mmHg, cardiac arrest, severe respiratory distress, or syncope with suspected PE — these indicate massive PE requiring thrombolysis or surgical embolectomy.

Arrange same-day ED transfer for: suspected PE with high clinical probability, any haemodynamic borderline case, significant hypoxia unresponsive to oxygen, or troponin elevation suggesting intermediate-high-risk disease.

Refer to haematology or thrombosis service: unprovoked PE for thrombophilia workup after acute treatment; recurrent VTE; inherited thrombophilia or confirmed antiphospholipid syndrome; cancer-associated PE requiring complex anticoagulation decisions; patients in whom all DOACs are contraindicated.

What this article is and is not

This is general health information drawing on eTG, AMH, RACGP, THANZ, and the ESC 2019 PE guideline. It does not constitute personal medical advice and does not create a doctor–patient relationship. Decisions about anticoagulant choice, treatment duration, and specialist referral are made in consultation with your GP and treating team, taking into account your individual clinical circumstances, kidney function, bleeding risk, and preferences.

For AU consumer information: HealthDirect — Pulmonary embolism, Better Health Channel — Blood clots, Lung Foundation Australia, THANZ.

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Sources cited

1. RACGP — Venous thromboembolism resources
2. Therapeutic Guidelines (eTG) — Venous thromboembolism
3. Australian Medicines Handbook (AMH)
4. THANZ — Thrombosis and Haemostasis Society of Australia and New Zealand
5. Lung Foundation Australia
6. Heart Foundation Australia
7. HealthDirect — Pulmonary embolism
8. Better Health Channel — Blood clots
9. ESC 2019 Guidelines — Pulmonary embolism
10. NICE NG158 — Venous thromboembolic diseases
11. Agnelli G et al. AMPLIFY — apixaban for VTE (NEJM 2013)
12. EINSTEIN-PE Investigators — rivaroxaban for PE (NEJM 2012)
13. Raskob GE et al. HOKUSAI-VTE Cancer (NEJM 2018)
14. Agnelli G et al. CARAVAGGIO — apixaban for cancer-associated PE (NEJM 2020)
15. Righini M et al. ADJUST-PE — age-adjusted D-dimer (JAMA 2014)