Open AccessAcute Effects of Ivabradine on Dynamic Obstruction of the Left Ventricular Outflow Tract in Cats with Preclinical Hypertrophic Cardiomyopathy
Author(s) -
Blass K.A.,
Schober K.E.,
Li X.,
Scansen B.A.,
Bonagura J.D.
Publication year - 2014
Publication title -
journal of veterinary internal medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.356
H-Index - 103
eISSN - 1939-1676
pISSN - 0891-6640
DOI - 10.1111/jvim.12331
Subject(s) - ivabradine , medicine , atenolol , hypertrophic cardiomyopathy , cardiology , cats , heart rate , ventricular outflow tract , chronotropic , blood pressure , anesthesia
Background Ivabradine is a negative chronotropic drug with minimal effects on central hemodynamics. Its effect on dynamic obstruction of the left ventricular outflow tract ( LVOT ) in cats with hypertrophic cardiomyopathy ( HCM ) remains unknown. Hypothesis/Objectives Ivabradine reduces dynamic obstruction of the LVOT in cats with HCM . Animals Twenty‐eight client‐owned cats with preclinical HCM and dynamic LVOT obstruction. Methods Randomized, double‐blind, active‐control single dose study. Cats received a single dose of either ivabradine (0.3 mg/kg PO ) or atenolol (2 mg/kg PO ). Heart rate, echocardiographic variables, and systolic blood pressure ( SBP ) were recorded before and 3 hours after drug administration. Statistical comparisons were made using ANCOVA . Results Peak velocity in the LVOT was significantly decreased compared to baseline for both drugs; however, the effect was more prominent with atenolol (mean reduction 2.53 m/s; 95% CI 2.07–3.13 m/s) compared to ivabradine (mean reduction 0.32 m/s; 95% CI −0.04 to 0.71 m/s; P < .0001). Echocardiographic indices of systolic function were largely unchanged by ivabradine, but significantly reduced by atenolol. Conclusions and Clinical Importance A single dose of ivabradine decreases dynamic LVOT obstruction in cats with HCM , but the clinical effect is negligible and inferior compared to that achieved by atenolol.