Acute pulmonary embolism risk stratification.

Acute pulmonary embolism (PE) is a complex heterogenous condition that affects 0.5 - 1 per 1000 persons in the general population each year, and is one of the most common preventable causes of death among hospitalized patients. 1 In the United State, PE kills more than 200,000 patients every year; more than breast cancer, HIV, and motor vehicle accidents combined. 2 Pulmonary embolism has varying early and long-term outcomes. The mortality rate of acute PE varies from almost 0% (in asymptomatic small PE) to more than 60% in life-threatening major PE patients, who present in cardiac arrest; 3 most deaths, however, occur in the first 2 hours of presentation. Overall, the mortality rate in PE patients is found to be higher than in patients with acute myocardial infarction, exceeding 10% at 30 days and 16% at 3 months. 4 Within 30 days, the most common cause of death is right ventricular failure and pulmonary hypertension, while most deaths beyond 30 days are often due to the underlying comorbid chronic conditions, such as congestive heart failure, chronic obstructive lung disease, or malignancy. As of this variable result, one of the most important task of the treating physician is to apply a clear, evidence-based risk stratification strategy, in order to detect those patients who are likely to have a complicated and poor result and to institute a proper early therapeutic intervention. By applying risk stratification model, patients estimated to be at low risk could be discharged early or managed entirely as outpatients using low-molecular-weight heparin, whereas patients estimated as high risk should be admitted for extensive and supervised therapy. The 5 steps that are required for adequate risk stratification of acute PE are as following: 1. Clinical assessment. The presence of comorbid illnesses (such as advanced age, congestive heart failure, malignancy, or chronic lung disease) increases the risk of adverse clinical events, even in the presence of anatomically small PE. In the International Cooperative Pulmonary Embolism (ICOPER) registry, 4 the presence of comorbidities was associated with an approximately 2-fold increase in the risk of death at 3-month. Clinically, the presence of severe dyspnea and syncope usually indicate hemodynamically significant PE. The clinical examination might support this by showing signs of acute right ventricular dysfunction, including tachycardia, distended neck veins, an accentuated pulmonic component of the second heart sound, or a tricuspid regurgitation murmur. The presence of hemodynamic instability or shock status has a prognostic value and significant increase in mortality compared to hemodynamically stable patients (30% versus <5%). Patients who present with cardiac arrest have a mortality rate approaching 60%. The Geneva Prognostic Index (GPI) has been developed as a tool for severity assessment to identify low-risk patients. It is based on the findings from the medical history and the clinical examination. Using GPI, risk stratification is performed using an 8-point scoring system and identifies 6 predictors of adverse result: 2 points each for cancer and hypotension and 1 point each for heart failure, previous deep vein thrombosis (DVT), arterial hypoxemia, and ultrasoundproven DVT. The higher the scoring points, the worse the result. Patients who score less than 2 were found to have an extremely good prognosis. 4 Finally, the presence of prior and idiopathic PE, younger age, or a large perfusion defect on perfusion scan has been shown to be associated with increased risk for the developing chronic thromboembolic pulmonary hypertension (CTEPH) during the ensuing 2 years. 5