Evaluation of the Calcium Channel‐Blocking Agents Diltiazem and Verapamil for Treatment of Feline Hypertrophic Cardiomyopathy

Abstract

To determine the efficacy of and clinical response to several pharmacologic agents for treatment of idiopathic hypertrophic cardiomyopathy in cats, 17 symptomatic cats were randomized to treatment with either propranolol, diltiazem, or verapamil. Clinical, laboratory, radiographic, electrocardiographic, and echocardiographic data were obtained before treatment and after 3 and 6 months of chronic oral therapy.Too few of the cats receiving propranolol or verapamil survived long enough to obtain long-term data needed to make statistical comparisons between groups. However, all 12 cats ultimately treated with diltiazem became asymptomatic, and no adverse effects from this drug were noted in any of these cats. Treatment with diltiazem was associated with a significant reduction of pulmonary congestion assessed radiographically (P < 0.01), and improved ventricular filling based on echocardiographic measurements of left atrial size (P < 0.05), left ventricular internal diastolic dimension (P < 0.05), and relaxation time index (P < 0.001). There was also a drug-related improvement in jugular venous oxygen tension (P PRIMARY HYPERTROPHIC CARDIOMYOPATHY (HCM) is a common cause of heart failure and sudden death in cats. The disease is characterized by a hypertrophied, nondilated left ventricle with subsequent resistance to diastolic filling. Impaired diastolic function may result in increased left ventricular filling pressures, pulmonary edema, and dyspnea as well as inadequate cardiac output, fatigue, lethargy, and sudden death. Currently, a recommended treatment for feline HCM is beta-adrenergic blockade, usually with propranolol, as well as cautious use of diuretics to control pulmonary congestion.' However, the response to propranolol in

Ventricular Tachyarrhythmias in 106 Cats: Associated Structural Cardiac Disorders

“…The results of the present study indicated that the large majority (102/106; 96%) of cats with ventricular tachyarrhythmias had underlying structural heart disease that was identified echocardiographically. The spectrum of echocardiographic diagnoses in the results of this study (1998–2002) was similar to historical reports, 1–10 with the exception that these reports indicated a higher prevalence of DCM before the identification of taurine deficiency as a cause of feline DCM 3,4…”

“…To date, ventricular tachyarrhythmias have been described in association with several naturally occurring disorders in cats, including HCM, 3–6 DCM, 3,4 R/UCM, 4 hyperthyroidism, 8,9 bacterial endocarditis, 7 and cardiac neoplasia 10 . However, the proportion of cats with ventricular tachyarrhythmias that have structurally normal hearts and the echocardiographic features of a population of cats with ventricular tachyarrhythmias have not been investigated extensively to date.…”

“…In some species of animals, associations between ventricular tachyarrhythmias and concurrent problems are well known 1,2 . However, in cats, the factors and potential triggers that are associated with naturally occurring ventricular tachyarrhythmias have been described only briefly 1–10 . By retrospective review of medical records, we sought to determine the echocardiographic diagnoses associated with naturally occurring ventricular tachyarrhythmias in cats and to compare these findings with equivalent information in dogs.…”

Feline Cardiomyopathy

“…53 Diltiazem was the most efficacious of the three. In a small, open-label clinical trial, the effects of diltiazem, propranolol, and verapamil on cats with pulmonary edema caused by HCM were compared.…”

Analysis of diltiazem in Lipoderm® transdermal gel using reversed-phase high-performance liquid chromatography applied to homogenization and stability studies

“…Diltiazem is a calcium channel antagonist used in the treatment of angina, hypertension, and arrhythmias in humans as well as hypertrophic cardiomyopathy in cats [1,2]. The structure of diltiazem is presented in Fig.…”