HCM is a disease of diastolic dysfunction (impaired relaxation and increased stiffness of primarily the left ventricle), thus therapies are aimed at improving diastolic function and resolving signs of congestion. Additional goals include treatment of malignant arrhythmias for the prevention of sudden death, and prevention of thromboembolic disease. For a discussion of the treatment of HCM, visit the following link.
Dante was treated in the ICU with oxygen, rewarming, intravenous furosemide (2 mg/kg BID), and minimal handling. Oral atenolol was also initiated (12.5 mg SID). Furosemide, as a diuretic, is indicated to treat the pulmonary edema, and atenolol, which is a beta-blocker, is used to decrease dynamic outflow obstruction, improve diastolic function, and improve myocardial perfusion. It also possesses antiarrhythmic properties. After 24 hours, Dante's breathing and thoracic radiographs were much improved and he began to eat, thus he was discharged to his owners. Therapy to be continued at home consisted of atenolol at 12.5 mg once daily for 7 days followed by twice daily, furosemide 5 mg twice daily, and aspirin 80 mg once every three days. A recheck examination was scheduled for one week later. Periodic rechecks are essential to monitor cardiac, respiratory, and renal function, and to adjust medical therapy.
Sequelae to HCM include worsening CHF, sudden death presumably due to arrhythmias, and aortic thromboembolism, and most symptomatic cats with HCM will succumb to one of these three. Retrospective studies looking at cats with HCM and CHF report a fairly wide range of median survival times, from 92 to 563 days. These cats typically experience stable (and even diuretic-free) periods, potentially for many months, interspersed with acute exacerbations.