Evaluation of pimobendan and N-terminal probrain natriuretic peptide in the treatment of pulmonary hypertension secondary to degenerative mitral valve disease in dogs.
BACKGROUND
Pimobendan is a positive inotrope and vasodilator that may be useful in the treatment of pulmonary hypertension (PHT) secondary to degenerative mitral valve disease.


OBJECTIVE
Pimobendan decreases the severity of PHT measured echocardiographically and improves quality-of-life scores. Changes in N-terminal probrain natriuretic peptide (NT-proBNP) concentrations will reflect improvement in severity of PHT.


METHODS
Ten client-owned dogs with peak tricuspid regurgitant flow velocity (TRFV) > or =3.5 m/s.


METHODS
Prospective short-term, double-blinded, crossover design, with a long-term, open-label component. Short term, dogs were randomly allocated to receive either placebo or pimobendan (0.18-0.3 mg/kg PO q12 h) for 14 days. After a 1-week washout, they received the alternative treatment for 14 days, followed by pimobendan open-label for 8 weeks.


RESULTS
Short-term comparison: peak TRFV decreased in all dogs on pimobendan compared with placebo from a median of 4.40 (range, 3.2-5.6) to 3.75 (range, 2.4-4.8) m/s (P < .0001). NT-proBNP concentration decreased after treatment with pimobendan from a median of 2,143 (range, 450-3,981) to 1,329 (range, 123-2,411) pmol/L (P= .0009). All dogs improved their quality-of-life score (P= .006). In the long-term comparisons, peak TRFV decreased in all dogs from a median of 4.28 (range, 3.5-5.7) to 3.52 (range, 2.4-5.0) m/s (P < .0001). No significant changes in NT-proBNP or quality-of-life scores were detected.


CONCLUSIONS
Pimobendan lowered severity of measurable PHT, improved quality-of-life scores, and decreased NT-proBNP concentrations short-term. Long term, only the reduction in TRFV was maintained.
Atkinson
K J
KJ
Departments of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, MO, USA. atkinson@heartvet.com
Fine
D M
DM
Thombs
L A
LA
Gorelick
J J
JJ
Durham
H E
HE
D000818:Animals; D002316:Cardiotonic Agents / Q000627:therapeutic use; D004283:Dog Diseases / Q000097:blood / Q000188:drug therapy*; D004285:Dogs; D004311:Double-Blind Method; D006976:Hypertension, Pulmonary / Q000188:drug therapy / Q000209:etiology / Q000662:veterinary*; D008944:Mitral Valve Insufficiency / Q000150:complications / Q000188:drug therapy / Q000662:veterinary*; D020097:Natriuretic Peptide, Brain / Q000627:therapeutic use*; D010446:Peptide Fragments / Q000627:therapeutic use*; D011724:Pyridazines / Q000627:therapeutic use*
D002316:Cardiotonic Agents; D010446:Peptide Fragments; D011724:Pyridazines; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain; C041648:pimobendan