Suspected high-output heart failure secondary to severe hypotension caused by the combination therapy of antihypertensive drugs in a cat

A 12-year-old, spayed, female Maine Coon was referred for uncontrolled systemic hypertension despite benazepril. We diagnosed hypertrophic cardiomyopathy phenotype, and combination treatment with benazepril and amlodipine effectively controlled the hypertension. After that, 2 weeks after the substitution of benazepril with telmisartan, the cat visited for emergency treatment of polydipsia and respiratory distress (Day 72). The cat had a severe hypotension, whereas left ventricular function was preserved, an impaired left atrial function, and pulmonary oedema. The cat was managed in an oxygen chamber with withdrawal of antihypertensives and furosemide administration. On Day 73, blood pressure normalised, and higher cardiac output was recognised. In addition, decreased systemic vascular resistance index was identified by comparing with the systemic vascular resistance index after discharge. Based on the above, it is inferred that high-output heart failure had developed by at least Day 73. To our knowledge, this is the first report of high-output heart failure triggered by severe, antihypertensive drug-induced hypotension.