The number of cats requiring treatment for hypertrophic cardiomyopathy (HCM) and arterial thromboembolism (ATE) continues to increase, and the knowledge regarding its management is constantly evolving. The pathological lesions of HCM include hypertrophy of the left ventricle, which causes abnormalities in the relaxation function of the heart. This phenomenon increases the stiffness of the ventricular muscle, thereby reducing the ability of the left ventricle to fill with blood during diastole. This is accompanied by an increase in ventricular filling pressure and left atrial pressure. HCM in cats is characterized by concentric hypertrophy and atrial enlargement. Hypertrophic obstructive cardiomyopathy (HOCM) also involves a narrowed left ventricular outflow tract, and in humans, it is generally perceived to be a more serious disease. However, unlike in humans, HCM and HOCM in cats do not result in significantly different survival times. Heart murmurs, gallop rhythms, arrhythmias, cardiac hypertrophy, congestive heart failure (CHF), ATE, and cardiac sudden death (CSD) have all been associated with HCM. Although the presence of a heart murmur is a characteristic feature of heart disease, it may be a functional one, which is defined as “dynamic right ventricular outflow track obstruction” (DRVOTO) in cats. Therefore, it is difficult to evaluate the presence of HCM based on the existence of a heart murmur alone. ATE typically affects one or both hind limbs, resulting in acute paralysis and severe pain, consistent with lower motor neuron disease. The clot, which is formed in the left atrium of the heart, travels to an artery and becomes an ATE, which then blocks the blood flow and impairs circulation, causing infarction. Therefore, ATE in cats is a serious condition. This review describes the results of the latest research on HCM and ATE, the most common heart conditions in cats.

Hypertrophic cardiomyopathy (HCM) is recognized as the most common feline cardiac disease. Several studies have evaluated the population characteristics and survival time of cats with HCM; however, these reports included large numbers of asymptomatic HCM. The purpose of this study was to evaluate the characteristics and survival time of cats with symptomatic HCM admitted to emergency service. Medical records were examined to verify clinical diagnosis of HCM. Asymptomatic cats diagnosed with HCM were also excluded from the study. From a total of 13 cats, eight were classified in the arterial thromboembolism (ATE) group while the other five were in the congestive heart failure (CHF) group. Middle-aged (6 years, range 1.4~7 years) male cats (53.8%) were included in this study. Pelvic limb paralysis, depression, and respiratory distress were common clinical signs found in symptomatic HCM cats. Hematologic evaluation found that enzymes related to muscle damage and tissue necrosis were elevated in both groups and highly elevated in the ATE group. Left atrium was remarkably enlarged in ATE group cats. The median survival time of cats in the ATE group was significantly shorter than that of cats in the CHF group (P=0.002). Prospective investigation based on a large population would be required to clarify the effects of various factors on prognosis of HCM cats.

The isolated single coronary artery is a rare congenital anomaly, in which both coronary arteries arise from a solitary ostium. Diagnosis of coronary anomalies and identification of the exact anatomy of coronary arteries has significant clinical importance, hence, myocardial ischemia or sudden cardiac death is usually related to its course of anomalous coronary artery. Most patients with a single coronary artery are asymptomatic and have normal electrocardiogram and negative stress tests. However, if the patient has other structural abnormalities, for example, ventricular hypertrophy, the exam is determined. This report describes a case of single coronary artery, where the right coronary artery originated from the distal left circumflex artery in a patient with hypertrophic ardiomyopathy.