Role of NT-proBNP and 6MWD in chronic thromboembolic pulmonary hypertension.
BACKGROUND
This study aims to evaluate the role of NT-proBNP and six minute walking distance (6MWD) in the pre- and post-operative assessment of subjects undergoing pulmonary endarterectomy (PEA) for chronic thromboembolic pulmonary hypertension (CTEPH).


METHODS
Subjects undergoing PEA between August 2004 and July 2006 were assessed at baseline and 3 months post-operatively with resting haemodynamics, NT-proBNP and 6MWD.


RESULTS
A number of 111 subjects underwent surgery, of which 102 were included. 15 subjects died before their 3 month assessment. Non-survivors had significantly worse preoperative NT-proBNP and 6MWD (4728 pg/mL vs 1863 pg/mL, p=0.001, 182.4 m vs 263.5 m, p=0.001). Taking pre-operative cut-off values of 1200 pg/mL for NT-proBNP and 345 m for 6MWD, both tests had high negative predictive value for predicting mortality (97.3% and 100%, respectively). Amongst survivors, peri-operative changes in NT-proBNP and 6MWD correlated with changes in total pulmonary resistance (TPR) (r=0.49, p<0.001 and r=-0.46, p<0.001). Post-operatively, both NT-proBNP and 6MWD also correlated with mPAP (r=0.65, p<0.001 and r=-0.50, p<0.001) and PVR (r=0.63, p<0.001 and r=-0.47, p<0.001). The ability of NT-proBNP to predict persistent pulmonary hypertension was significantly confounded by age, but not gender, BMI or renal function.


CONCLUSIONS
Pre-operative evaluation with NT-proBNP and 6MWD helps risk-stratify patients prior to PEA. Post-operatively, both markers correlate with changes in disease burden and right ventricular function. These results suggest that both NT-proBNP and 6MWD offer effective 'bedside' tools for the long term follow up of patients with CTEPH.
Suntharalingam
Jay
J
Pulmonary Vascular Diseases Unit, Papworth Hospital NHS Trust, Papworth Everard, Cambridgeshire, CB23 8RE, UK.
Goldsmith
Kimberley
K
Toshner
Mark
M
Doughty
Natalie
N
Sheares
Karen K
KK
Hughes
Rodney
R
Jenkins
David
D
Pepke-Zaba
Joanna
J
D000368:Aged; D002908:Chronic Disease; D004691:Endarterectomy; D017079:Exercise Tolerance; D005260:Female; D006439:Hemodynamics; D006801:Humans; D006976:Hypertension, Pulmonary / Q000097:blood / Q000209:etiology*; D008297:Male; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D018579:Patient Selection; D010446:Peptide Fragments / Q000097:blood*; D011184:Postoperative Period; D011237:Predictive Value of Tests; D011651:Pulmonary Artery / Q000503:physiopathology*; D011655:Pulmonary Embolism / Q000150:complications / Q000503:physiopathology* / Q000601:surgery; D013997:Time Factors; D018497:Ventricular Dysfunction, Right / Q000097:blood / Q000209:etiology; D017725:Ventricular Pressure
D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain