Pulmonary embolism natural history

Associate Editors-in-Chief: Ujjwal Rastogi, MBBS [mailto:urastogi@perfuse.org]

Overview
Pulmonary embolism is mostly a consequence of Deep vein thrombosis, thus natural history of VTE should be considered as a whole, instead of separately looking at DVT and PE.

Natural History
Approximately one-third of patients with pulmonary embolism who are not treated will die. without treatment, usually from recurrent PE. However, with diagnosis and treatment, the mortality rate is only ~ 2 – 8%. Unfortunately, 2/3 of all cases of PE are not diagnosed untill autopsy.

Prognosis
Mortality from untreated PE is said to be 26%. This figure comes from a trial published in 1960 by Barrit and Jordan which compared anticoagulation against placebo for the management of PE. Barritt and Jordan performed their study in the Bristol Royal Infirmary in 1957. This study is the only placebo controlled trial ever to examine the place of anticoagulants in the treatment of PE, the results of which were so convincing that the trial has never been repeated as to do so would be considered unethical. That said, the reported mortality rate of 26% in the placebo group is probably an overstatement, given that the technology of the day may have detected only severe PEs.

Prognosis depend upon:
 * The amount of lung that is affected
 * Co-existence of other medical conditions (Eg. chronic embolisation to lung can lead to pulmonary hypertension).

Prognostic Assessment
Factors predicting mortality in pulmonary embolism patients are: Observational studies like International COoperative Pulmonary Embolism Registry (IOCPER) and Management and Prognosis in Pulmonary Embolism Trial (MAPPET) have shown that Shock and hypotension are principal markers of high risk of early death in acute PE.
 * Clinical assessment of Haemodynamic status

Post hoc analysis of ICOPER study data showed, that, the 90-day all-cause mortality rate was 52.4% (95% CI,43.3–62.1%) in patients with systolic blood pressure less than 90 mmHg compared with 14.7% (95% CI, 13.3–16.2%) in normotensive patients.

According to the MAPPET study, systemic hypotension, seems to carry a slightly lower risk compared with shock (in-hospital all-cause mortality, 15.2 vs. 24.5%, respectively). According to PESI (Pulmonary Embolism Severity Index) trial, hypotension (blood pressure <100 mm Hg) is a significant risk factor causing mortality in half of the patient group.
 * Markers of Right ventricular dysfunction (RVD) 

Trials reporting significance of RV dysfunction (RVD) in Pulmonary embolism (assessed by echocardiography) Abbreviations Used: RV , right ventricle; TI, tricuspid insufficiency; LV, left ventricle; AcT, ACceleration Time of right ventricular ejection; TIPG, tricuspid insufficiency peak gradient.


 * Markers of Myocardial Injury
 * Brain natriuretic peptide

In patients with pulmonary embolism, elevated plasma levels of natriuretic peptides (brain natriuretic peptide and N-terminal pro-brain natriuretic peptide) have been associated with higher mortality.

A separate study involving 93 pulmonary embolism patients, concluded that the levels of N -terminal pro-brain natriuretic peptide greater than 500 ng/L could serve as an indicator of the burden of PE and perhaps as a predictor of death. Elevated serum troponin levels are associated with an increased risk of death in PE patients. Patients who died of massive PE were found to have transmural RV infarction, on autopsy, despite having patent coronary arteries.
 * Serum troponins

Hyponatremia at the time of presentation is associated with
 * Additional Risk Markers
 * DVT
 * Hyponatremia
 * Increased mortality
 * Hospital readmission.

There is controversy over, treatment of small subsegmental PE and some evidence exists that patients with subsegmental PEs may do well without treatment.

ECG findings can also help in assessing the prognosis. Please click here to read more.

Complications

 * Heart failure or shock
 * Palpitations
 * Pulmonary hypertension
 * Severe dyspnea
 * Severe bleeding (usually a complication of treatment)
 * Sudden death

Notable person who died from Pulmonary embolism are Rapper Heavy D  and NBC correspondent David Bloom. Tennis player Serene Williams, suffered an attack of PE, but was rescued on time.

ESC Guidelines for Prognostic assessment (DO NOT EDIT)
{{cquote|

Class I
1.Initial risk stratification of suspected and/or confirmed PE based on the presence of shock and hypotension is recommended to distinguish between patients with high and non-high-risk of PE-related early mortality. (Level of Evidence: B)

Class II
2.In non-high-risk PE patients, further stratification to an intermediate- or low-risk PE subgroup based on the presence of imaging or biochemical markers of RVD and myocardial injury should be considered.(Level of Evidence: B)}}

Guidelines Resources

 * Guidelines on the diagnosis and management of acute pulmonary embolism.