# Disopyramide Therapy in Cats with Obstructive Hypertrophic Cardiomyopathy Non-Responsive to Carvedilol

## TL;DR

This study explores using disopyramide to treat cats with heart disease that doesn't respond to standard drugs, showing improved heart function and no major side effects.

## Contribution

The study demonstrates disopyramide's efficacy in cats with obstructive hypertrophic cardiomyopathy non-responsive to beta-blockers.

## Key findings

- Disopyramide reduced left ventricular outflow tract obstruction in cats.
- The drug lowered cardiac troponin I levels, indicating reduced myocardial injury.
- No significant adverse effects were observed in treated cats.

## Abstract

Hypertrophic cardiomyopathy is the most common form of cardiomyopathy in cats. When accompanied by left ventricular outflow tract obstruction, the condition is typically managed with medical therapy in humans. Beta-blockers are generally the first-line treatment, but some cases do not respond to them. In such instances, the antiarrhythmic drug disopyramide is considered as an adjunctive therapy. However, its use in cats has only been documented in a case report. This study aimed to evaluate the efficacy of disopyramide as co-therapy in cats with hypertrophic cardiomyopathy and left ventricular outflow tract obstruction that are refractory to beta-blockers. In this study, adding disopyramide resulted in the alleviation of left ventricular outflow tract obstruction and improvement in myocardial function. Furthermore, disopyramide reduced cardiac troponin I levels, a cardiac biomarker indicating myocardial injury. The results suggest that disopyramide may be a potential therapeutic option for feline obstructive HCM, as no significant side effects were observed.

Hypertrophic cardiomyopathy (HCM) is the most common cardiomyopathy in cats and is classified as obstructive (HOCM) or non-obstructive based on anatomical differences in the left ventricular outflow tract (LVOT). In severe obstructive cases, while beta-blockers are the recommended initial treatment in humans, some patients exhibit treatment resistance. For these cases, the addition of the antiarrhythmic agent disopyramide is common. However, its use in cats has only been documented in a case report. In this study, the use of disopyramide resulted in a significant reduction in the LVOT velocity and cardiac troponin I levels. Additionally, no significant adverse effects were observed. These findings suggest that disopyramide could be a potential therapeutic option for the treatment in cats with HOCM.