Acute PE can present with a wide spectrum of symptoms and signs. Dyspnea is the most frequently reported symptom. Severe dyspnea, cyanosis, or syncope suggests a massive PE, whereas pleuritic pain, cough, or hemoptysis may indicate a smaller peripherally located PE. Because acute coronary syndromes are so common and clinical suspicion is often high, clinicians may overlook the possibility of a life-threatening acute PE and inadvertently discharge these patients from the hospital after the exclusion of myocardial infarction with serial cardiac biomarkers and electrocardiograms.

On physical examination, tachypnea is the most common sign. Patients without underlying cardiopulmonary disease may appear anxious but well compensated, even with an anatomically extensive PE. Patients with massive PE may present with systemic arterial hypotension, cardiogenic shock, or cardiac arrest. Submassive PE describes patients who have preserved systolic blood pressure but exhibit evidence of RV failure such as tachycardia, distended neck veins, tricuspid regurgitation, and an accentuated sound of pulmonic closure (P2).

Alternative diagnoses to PE include acute coronary syndromes, exacerbations of chronic obstructive pulmonary disease, aortic dissection, pneumonia, acute bronchitis, decompensated heart failure, pulmonary hypertension, pericardial disease, musculoskeletal pain, pneumothorax, and hepatobiliary or splenic pathology, which may lead to referred pleuritic discomfort (Table 5.1).

The laboratory evaluation of suspected acute PE should focus on the use of D-dimer testing in appropriately selected patients. Although it is nonspecific, D-dimer, as measured by enzyme-linked immunosorbent assay (ELISA), has utility in the evaluation of patients with suspected PE, especially in the Emergency Department setting. A study of patients with suspected acute PE in a high-volume Emergency Department demonstrated that the D-dimer ELISA had a sensitivity of 96.4 % and negative predictive value of 99.6 % [1]. Because of its high negative predictive value, the D-dimer ELISA can be used to exclude PE in outpatients with low to moderate pretest probability, without need for costly imaging and radiation exposure [2]. Most inpatients should proceed directly to an imaging study without D-dimer testing for PE because it is likely they will already have elevated D-dimers due to comorbid conditions.

The electrocardiogram may reveal the presence of RV strain or may suggest concomitant or alternative diagnoses such as myocardial infarction or pericarditis (Fig. 5.2). Signs of RV strain secondary to PE include incomplete or complete right bundle branch block (RBBB), T wave inversions in the anterior precordium, as well as an S wave in lead I and a Q wave and T wave inversion in lead III (S1Q3T3) (Table 5.2). Some patients may only demonstrate signs of increased adrenergic tone, with a resting sinus tachycardia. Furthermore, the electrocardiogram may be entirely normal, especially in young, previously healthy patients.