Pulmonary embolism (PE) is an extremely common and highly lethal condition that is a leading cause of death in all age groups. A good clinician actively seeks the diagnosis as soon as any suspicion of PE whatsoever is warranted, because prompt diagnosis and treatment can dramatically reduce the mortality rate and morbidity of the disease. Unfortunately, the diagnosis is missed more often than it is made, because PE often causes only vague and nonspecific symptoms.
The most sobering lessons about PE are those obtained from a careful study of the autopsy literature. Deep vein thrombosis (DVT) and PE are much more common than usually realized. Most patients with DVT develop PE and the majority of cases are unrecognized clinically. Untreated, approximately one third of patients who survive an initial PE die of a future embolic episode. This is true whether the initial embolism is small or large.
Most cases of PE are diagnosed at autopsy, and most who die of PE have not had any diagnostic workup or treatment of the disease. In most cases, the diagnosis has not even been considered, even when classic signs and symptoms are documented in the medical chart. Sadly, appropriate diagnostic and therapeutic management often is withheld even when the potential diagnosis of PE has been considered explicitly and documented in the chart.
* PE is the third most common cause of death in the US, with at least 650,000 cases occurring annually. It is the first or second most common cause of unexpected death in most age groups. The highest incidence of recognized PE occurs in hospitalized patients. Autopsy results show that as many as 60% of patients dying in the hospital have had a PE, but the diagnosis has been missed in about 70% of the cases. Surgical patients have long been recognized to be at special risk for DVT and PE, but the problem is not confined to surgical patients. Prospective studies show that in the absence of prophylaxis acute DVT may be demonstrated in any of the following:
o General medical patients placed at bed rest for a week (10-13%)
o Patients in medical intensive care units (29-33%)
o Patients with pulmonary disease kept in bed for 3 or more days (20-26%)
o Patients admitted to a coronary care unit after myocardial infarction (27-33%)
o Patients who are asymptomatic after coronary artery bypass graft (48%)
Not only are these patient groups at high risk for clinically unrecognized DVT, but half or more of the patients with DVT also can be shown to have suffered a PE, even though the majority have had none of the classic symptoms of PE.
* Internationally: Several papers suggest that the incidence of PE may differ substantially from country to country, but no prospective controlled studies lend support to this notion. The observed variance may be due more to differences in the rate of diagnosis than to differences in the frequency of the disease. If the differences are real, whether they are due to genetic variation or to population differences in diet and activity is not known.
* Massive PE is one of the most common causes of unexpected death, being second only to coronary artery disease as a cause of sudden unexpected natural death at any age. Most clinicians do not appreciate the extent of the problem, because the diagnosis is unsuspected until autopsy in approximately 80% of cases.
* Although PE often is fatal, prompt diagnosis and treatment can reduce the mortality rate dramatically.
o Approximately 10% of patients in whom acute PE is diagnosed die within the first 60 minutes. Of the remainder, the condition eventually is diagnosed and treated in one third and remains undiagnosed in two thirds.
o Among the group with PE that is correctly diagnosed and treated, only about one twelfth die from massive PE or its complications. Among the group with PE that is undiagnosed and therefore untreated, roughly one third die. The diagnosis of PE is missed more than 400,000 times in the US each year, and approximately 100,000 patients die who would have survived with the proper diagnosis and treatment.
* Patients who survive an acute PE are at high risk for recurrent PE and for the development of pulmonary hypertension and chronic cor pulmonale, which occurs in up to 70% of patients and carries its own attendant mortality and morbidity.
Race: Subtle population differences may exist in the incidence of DVT and PE, but the incidence is high in all racial groups.
Sex: PE is common in all trimesters of pregnancy and the puerperium, and the incidence of PE is increased in women receiving oral contraceptive or hormone replacement therapy; however, sex alone is not an independent risk factor.
* Although the frequency of PE increases with age, age is not an independent risk factor. Rather, the accumulation of other risk factors, such as underlying illness and decreased mobility, causes the increased frequency of PE in older patients.
* Unfortunately, the diagnosis of PE is especially likely to be missed in older patients. The correct diagnosis of PE is made in 30% of all patients who die with massive PE but in only 10% of those who are 70 years of age or older. It is the most commonly missed diagnosis responsible for death in the elderly institutionalized patient.
Bilateral means both sides are affected with pulmonary emboli.