Brian Locke

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.