Introduction: Acute pulmonary embolism (PE) is a common clinical entity in the emergency department, and remains a diagnostic challenge for physicians. The role of the 12-lead electrocardiogram (ECG) in its diagnosis and assessment of severity and prognosis is not as well defined as for acute coronary syndromes. We report four cases of massive and submassive PE with differing ECG findings admitted to an acute cardiac care unit. We review the role of different ECG abnormalities and also discuss the relevance of transthoracic echocardiographic data in the diagnosis and serial evaluation of patients with PE. Treatment options for PE with hemodynamic compromise and right ventricular dysfunction are also discussed.
Results: The ECG is abnormal in over two-thirds of patients with PE. Its main utility is in excluding other conditions, such as acute coronary syndromes.
Discussion: Numerous ECG abnormalities have been reported in patients with PE. These often change over time, with worsening or resolution of the embolic event. Although it is the most frequent ECG abnormality, sinus tachycardia lacks specificity. However, ECG findings are more specific in patients with severe PE (such as the classic S1Q3T3 pattern). In the case of massive and submassive PE, anterior and inferior T-wave inversion is the most frequent associated ECG finding. Serial ECG evaluation should be performed in such patients as changes and resolution of abnormalities may have prognostic implications. Transthoracic echocardiography is extremely useful in the initial and serial evaluation of patients with PE because of its accessibility and the data it provides on diagnosis, severity and resolution. Submassive PE is defined by echocardiographic data and could benefit from the same therapeutic options as for massive PE. The use of specific therapeutic strategies such as anticoagulant and thrombolytic therapy in both massive and submassive PE has to be carefully weighed. The bleeding risk and associated comorbidities of patients admitted with PE should always be considered.
Conclusion: ECG findings have low sensitivity and specificity in the diagnosis of PE. It should be routinely used in serial evaluations, particularly when hemodynamic compromise is present, and should be included in the range of diagnostic strategies available.