Poor Prognosis: Restrictive Cardiomyopathy

Both asymptomatic cats and those showing illness in study

A recent study out of Italy looked at survival and prognostic factors for cats with restrictive cardiomyopathy. The researchers looked at 90 cats who had been diagnosed with this cardiac condition via echocardiography between 1997 and 2015. There were 53 more males than females in the study.

Most of the cats were domestic shorthairs showing some signs of illness, including respiratory difficulty, but a few were asymptomatic at the time of their diagnosis. Respiratory distress was the most common sign, but some cats also had murmurs or cardiac arrhythmias. Chest radiographs showed pleural effusion in a majority of the cats, and most had enlargement of the left atrium of the heart on their echocardiogram studies.

Survival times, despite treatment with diuretics, ACE inhibitors, and medications to prevent clots, were relatively short. Many cats died within two months of diagnosis. A few cats who initially came in without respiratory distress survived for over a year. This form of cardiomyopathy is a difficult disease to treat, and the prognosis is guarded at best.

Cats can suffer from three types of cardiomyopathy. The dilated version is uncommon since taurine levels have been adjusted in cat foods. Hypertrophic is the most common, with restrictive second in prevalence.

The Cornell Feline Health Center reminds us that restrictive cardiomyopathy is caused by the excessive buildup of scar tissue on the inner lining and muscle of the ventricle, which prevents the organ from relaxing completely, filling adequately, and emptying normally with each heartbeat.n

J Feline Med Surg. 2018 Dec;20(12):1138-1143. doi: 10.1177/1098612X18755955