PE & the Epidemiology of CTEPH
Though rare, CTEPH may be more common than previously thought.
CTEPH is a rare but highly underdiagnosed form of pulmonary hypertension (PH). Considered uncommon, physicians don’t often test for CTEPH, and instead prescribe anticoagulants or other PH medications for “chronic clot,” “recurrent PE,” or other comorbidities like asthma or COPD.8
On average, there is a delay of well over a year in diagnosis of CTEPH.8 In one study, the 5-year survival rate in CTEPH patients who received no intervention was 30% with mPAP >40 mmHg and 10% with mPAP >50 mmHg.6
Data from multiple observational studies suggest that as many as 0.57% to 3.8% of patients may go on to develop CTEPH within 2 years after a first acute PE.6 Applying even the lower end of that range to the estimated 600,000 cases of acute PE per year in the US2 suggests the actual number of CTEPH cases developing each year may be substantially greater than diagnosed cases suggest.
Pengo et al conducted a prospective, observational, long-term, follow-up study to evaluate the incidence of symptomatic CTEPH in patients with an acute episode of PE but without prior venous thromboembolism. 314 patients who had an acute PE were evaluated. CTEPH was considered to be present if systolic and mean pulmonary artery pressures exceeded 40 mmHg and 25 mmHg, respectively; if pulmonary-capillary wedge pressure was normal; and if there was angiographic evidence of disease.7
The figure at right shows the cumulative incidence of symptomatic CTEPH over follow-up of as long as 10 years:
- 1% at 6 months (95% CI, 0.0 to 2.4)
- 3.1% at 1 year (95% CI, 0.7 to 5.5)
- 3.8% at 2 years (95% CI, 1.1 to 6.5)
- CTEPH did not develop after 2 years with a median follow-up of ≈8 years7
Results from this study illustrate the importance of awareness to the possibility of CTEPH in patients who experience a PE, especially in the first 2 years following PE diagnosis.
Remember: as many as 1 out of every 25 of your previously treated PE patients (>3 months of anticoagulation5) could go on to develop CTEPH.2,7*
*Based on a study with 223 patients in which 3.8% were diagnosed with CTEPH within 2 years of their first episode of pulmonary embolism with or without prior deep-vein thrombosis (95% CI, 1.1 to 6.5). CTEPH did not develop after two years in any of the 132 remaining patients with more than 2 years of follow up.
CTEPH does not always include a history of documented PE
A European registry which published results in 2011 demonstrated that 74.8% of CTEPH patients presented with previous acute PE, while 56.1% presented with previous deep vein thrombosis.8
Yet, as many as 30% of patients who have CTEPH may never have had an overt PE.9 The true incidence of CTEPH may be underestimated, because postembolism observational studies do not include patients who have no history of venous thromboembolism.6
Without intervention, survival with CTEPH is poor. To define the true epidemiology and natural history of CTEPH, further studies are needed.2
Up to 30% of CTEPH patients may not have had an overt PE.
Adapted from Pengo et al.7