# CTEPH

No longer clot in the vessels -> it is scar (hence, it has structure and can be removed by endarterectomy)

Symptoms: Primarily dyspnea on exertion.

1. pHTN -> increased workload on R ventricle and inability to increase cardiac output in response to exercise.
2. Chronic V/Q mismatch -> creates areas of deadspace ventilation and doesn't improve with exercise.

### Definition
Group 4 = artery

1. Meet definition of pre-cap pulm HTN:
1mPAP >25 mmHg (last WHO congress changed it to 20 = 2 SD above mean, whereas 25 was made up.), PCWP < 15 mmHg, PVR > 3 woods units.

2. Evidence of pulmonary thromboembolic disease on imaging: abnormal perfusion lung scan and thromboembolic disease by anatomic imaging (CTPA, MRA, or pulm angio)

3. Must have completed 3 months of anticoagulation

Note: group 4 also includes angiosarcoma, metastasis, arteritis, congenital pulmonary artery stenosis, and parasites. 

CTED: chronic thromboembolic disease = has symptoms consistent with CTEPH (dyspnea on exertion), imaging consistent, but don't meet baseline level of pulmonary hypertension, AND has CPET that demonstrates that exercise limitation is due to V/Q mismatch (high ve vco2, high vd vt that does not appropriately decrease with intensity). 

(last piece is important because 50% will have some exertional dyspnea after PE - perhaps due to )

### Workup

2 routes to diagnosis: 

1. Acute/subacute symptoms -> diagnosis of acute PE -> residual dyspnea
2. Subacute/chronic symptoms -> workup demonstrates findings of PH -> evaluation for CTEPH shows chronic PE (likely were having small, sub-clinical events). STILL need 3 months of anticoagulation prior to meeting diagnostic crisis. 

3 months of adequate anticoagulation is technical definition, though issue of recurrent clots is tricky. 

Screening for CTEPH in all patients is not effective 
-> only investigate patients who have residual dyspnea after 3-6 months.

Do not screening with TTE (*misses CTED and CTEPH with mild pH*) - only useful if they had a very abnormal acute TTE

V/Q - this is the initial test. (SPECT-CT is a similar, but better overlayed perfusion matching - but doesn't require ventilation component of scan). For CTEPH, uses different than PIOPED low/med/high probability nomenclature. 

CTPA (features can be suggestive of chronic PE, but not 100%. All clot that is still there at 6 months of anticoagulation will not resolve). Roughly 90% sensitive for chronic PE. Can show distal pruning. Can see mosaic perfusion on contrast scan due to differences in perfusion. 

and conventional angiography

### Who gets CTEPH?

Chronic PE = imaging finding of a narrowing / WEB after a PE with no clear physiologic impact. 30-50% of survivors. 

About 3% of PE survivors will develop CTEPH when followed by TTE. Diagnosed within 2 years. In clinical practice, we probably only catch 1 in 5. 

Note: some patients probably already had CTEPH at time of 'acute PE' diagnosis. 

Median age 63 years (older than group 1) but large spread. Males:Females equal.

Predictors of CTEPH: Unprovoked PE, prolonged symptoms (2 weeks of symptoms), proximal PE, and R heart strain / elevated RVSP (may just identify those who already have it). 

No difference based on aggressive up front PE treatment (e.g. lytics, catheter)

### Treatment

Largely based on the anatomy

If candidates (e.g. proximal clots, can undergo surgery) - endarterectomy is preferred. PTE preferred fo lobar or main arteries for sure. Segmental is maybe. 

Distal (e.g. subsegmental) disease - balloon pulmonary angioplasty. Pushes the lacy, reticulated scar out to the outside of the vessel. Average ~5 procedures; complications in 1/3 but most common is hemoptysis. Outcome -> mPAP to ~35

Can use PH drugs (if not surgical candidate; if distal disease alone or in combination with balloon angioplasty; or if residual disease after PTE)

- riociguat cGMP/NO pathway - only FDA approved medication. CHEST study (2013, NEJM; 6 mw distance as primary outcome)
- some data for Macitentan (off-label)

Residual PH after PTE - may have an arteriopathy related to remodeling from higher pressure in the remaining vessels (similar to group 1) -> hence PH medical treatments.