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Post-carvedilol myocardial function in cats with obstructive hypertrophic cardiomyopathy
Takahiro Saito1,2, Ryohei Suzuki1, Yunosuke Yuchi1,3
1Laboratory of Veterinary Internal Medicine, School of Veterinary Medicine, Faculty of Veterinary Science, Nippon Veterinary and Life Science University, Tokyo, Japan.
Insights
Carvedilol effectively treated obstructive hypertrophic cardiomyopathy (HCM) in cats by resolving dynamic left ventricular outflow tract obstruction (DLVOTO) and improving myocardial function. This study suggests carvedilol is a promising treatment for feline obstructive HCM.
Area of Science:
- Cardiology
- Veterinary Medicine
- Pharmacology
Background:
- Hypertrophic cardiomyopathy (HCM) is common in cats, often presenting as obstructive HCM with dynamic left ventricular outflow tract obstruction (DLVOTO).
- Myocardial function is typically reduced in cats with obstructive HCM compared to non-obstructive forms.
- The efficacy of carvedilol on myocardial function in cats with obstructive HCM and DLVOTO has not been previously reported.
Purpose of the Study:
- To evaluate the effects of carvedilol on myocardial function in cats diagnosed with obstructive HCM and DLVOTO.
- To assess changes in left ventricular outflow tract pressure gradients following carvedilol administration.
Main Methods:
- A retrospective observational study involving 16 cats with obstructive HCM treated with carvedilol.
- Conventional echocardiography combined with layer-specific 2D speckle tracking echocardiography to measure strain and strain rates.
- Comparison of echocardiographic variables before and after carvedilol treatment.
Main Results:
- Carvedilol administration resolved DLVOTO in all cats, evidenced by a decrease in maximal LV outflow tract blood flow velocity to <2.5 m/s (P < 0.01).
- Significant improvement in circumferential strain (epicardial and whole layer) was observed post-treatment (P < 0.01, P = 0.04).
- No significant changes were noted in systolic longitudinal strain before and after treatment.
Conclusions:
- Carvedilol treatment effectively improved DLVOTO and enhanced myocardial function in cats with obstructive HCM.
- The treatment did not induce a negative inotropic effect, suggesting carvedilol's potential as a therapeutic agent for feline obstructive HCM.
Introduction:
Hypertrophic cardiomyopathy (HCM) is the most prevalent cardiac disease in cats, and one phenotype includes obstructive HCM with dynamic left ventricular outflow tract obstruction (DLVOTO). Myocardial function has been reported to be lower in cats with obstructive HCM than in non-obstructive HCM. Carvedilol, because of its pharmacological action, is expected to reduce the pressure gradient associated with DLVOTO, but no previous reports have studied its effects on myocardial function. This study aimed to evaluate myocardial function in cats with obstructive HCM with left ventricular outflow tract obstruction treated by carvedilol administration.
Methods:
This retrospective observational study included 16 cats with obstructive HCM and subsequent treatment of DLVOTO with carvedilol. In addition to conventional echocardiography, strain and strain rates in the left ventricular longitudinal and circumferential directions were measured using layer-specific two-dimensional speckle tracking echocardiography. Each variable was then compared before and after carvedilol medication.
Results:
Systolic anterior motion of the mitral valve disappeared in 14 cats and all cats showed resolved DLVOTO with maximal left ventricular outflow tract blood flow velocity of <2.5 m/s after carvedilol administration (P < 0.01). Circumferential strain in the epicardial layer and in the whole layer was significantly increased after carvedilol administration (P < 0.01, P = 0.04, respectively). In contrast, systolic longitudinal strain showed no significant difference between before and after carvedilol administration.
Conclusion:
Treatment of obstructive HCM with carvedilol improved DLVOTO and myocardial function without a negative inotropic effect. Carvedilol may be effective in treating cats with obstructive HCM.
