Dr. Monish Raut discusses the recent 2019 ESC and ERS guidelines for Acute Pulmonary Embolism (PE), specifically, diagnosis and risk stratification in clinical practice.

The 2019 European Society of Cardiology (ESC) and European Respiratory Society (ERS) Guidelines for the Diagnosis and Management of Acute Pulmonary Embolism (PE) highlights some important aspects of acute pulmonary embolism management.

After myocardial infarction and stroke, venous thromboembolism comprising of pulmonary embolism or deep venous thrombosis is the third most common cause of acute cardiovascular syndrome all over the world. Incidence rates of pulmonary embolism is 39 to 115 per 1 lakh population; incidence rates of DVT is 53 to 162 per 1 lakh population.

Epidemiological studies from European countries have suggested that 34% succumbed to death suddenly or within a short time of the acute event. In remaining patients, 59% of the patients were diagnosed with acute PE after death and pulmonary embolism was correctly diagnosed in only 7% of the patients before death. This underlies the significance of early and proper diagnosis of pulmonary embolism which affects the prognosis. Recently, clinical implementation of guidelines has been shown to affect the prognosis of PE positively.

---

Knowing the risk factors forms the first step in constructing the diagnosis.

Major surgery, trauma, orthopaedic joint replacement surgery, cancers, oestrogen-containing oral contraceptive agents, smoking, and myocardial infarction are some of the strong and well-recognised provocative risk factors.

Nowadays, clinicians are more inclined to perform diagnostic workup for PE due to rising incidences of the disease and easy availability of computed tomography (CT) pulmonary angiography (CTPA). In such a scenario, assessment using pre-test probability of the disease plays an important role to avoid unnecessary tests.

---

Clinical presentation

The clinical manifestations of acute pulmonary embolism are non-specific. Symptoms are shortness of breath, chest discomfort, haemoptysis or syncope. Extensive or central pulmonary embolism may sometimes present with haemodynamic instability.

Suspicion of the disease increases with the presence of predisposing factors. However, it should be noted that risk factors are not present in 40% of the patients with pulmonary embolism. Electrocardiogram may suggest changes S1Q3T3 pattern, right bundle branch block, inverted T waves in leads V1–V4 and most commonly sinus tachycardia. Chest x-ray is non-specific and not conclusive, but can rule out other causes of dyspnoea. Although hypoxemia is commonly observed, normal hemoglobin saturation is observed in 40% of the patients.

---

Pathophysiology of PE

Acute Pulmonary embolism significantly affects RV and LV function and thereby, haemodynamics.

---

Assessment of clinical (pre-test) probability

Clinical manifestations and predisposing factors may give clues for the diagnosis of pulmonary embolism. However, pretest probability assessment can effectively categorise suspected pulmonary embolism patients.

---

Doubt of pulmonary embolism in patients with chest discomfort and breathlessness may lead to performing various unnecessary investigations at high cost. The Pulmonary Embolism Rule-out Criteria (PERC) can be useful in the emergency department.

---

D-dimer testing

D-dimer levels are raised in patients with acute thrombosis due to concomitant activation of coagulation and fibrinolysis. As D-dimer test is having high negative predictive value, a normal D-dimer level rules out acute PE or DVT.

ELISA-derived D-dimer assays have a diagnostic sensitivity of more than 95%. However, point-of-care D-dimer assays have a lower sensitivity and negative predictive value.

Recent ESC guidelines have emphasised validated age-adjusted cut-off (age × 10 µg/L, for patients aged >50 years). Age adjusted cut off D-dimer rather than ‘standard’ 500 µg/L can effectively exclude PE without additional false negative findings.

Computed tomographic pulmonary angiography guided visualisation of sub-segmental pulmonary arteries can confirm pulmonary embolism. It has got a sensitivity of 83% and a specificity of 96% for PE.

Ventilation/perfusion (V/Q) scan is a diagnostic test for suspected PE, especially in patients with low clinical probability, a normal chest X-ray, in pregnant women, contrast allergy and kidney disease.

---

Echocardiography

Acute pulmonary embolism can potentially lead to RV strain and dysfunction which can be diagnosed on echocardiography. However, echocardiography has negative predictive value of 40 to 50%. Hence, a negative result cannot rule out pulmonary embolism.

RV dysfunction implies the risk of early high mortality.

---

Echocardiographic findings of RV dysfunction

• Enlarged RV
• RV/LV ratio >1.0
• Flat IV septum
• Dilated IVC with reduced inspiratory collapsibility
• 60/60 sign- PAT <60 msec; TRPG <60 mmHg
• Right heart mobile thrombus
• Reduced TAPSE
• Reduced peak systolic tricuspid annular velocity

Compression ultrasonography in lower legs can diagnose DVT with a sensitivity >90% and a specificity of 95%

 

---

 

Assessment of pulmonary embolism severity and the risk of early death

Risk stratification of patients with acute PE is essential for proper therapeutic management approach.

---

Pulmonary Embolism Severity Index (PESI) which considers clinical, imaging, and laboratory findings along with comorbidities, can reliably recognize the patients at low risk for 30 day mortality. This scoring system has been most extensively validated.

Disclaimer- The views and opinions expressed in this article are those of the author's and do not necessarily reflect the official policy or position of M3 India.

The author, Dr. Monish S Raut is a Consultant in Cardiothoracic Vascular Anaesthesiology. His area of expertise is perioperative management and echocardiography with numerous publications in various national and international indexed journals.