Time to refractory congestive heart failure in cats presenting with pleural effusion vs. pulmonary edema.

Introduction/objectives: Cats with left-sided congestive heart failure (CHF) usually present with pleural effusion and/or pulmonary edema. We compared time to refractory CHF and survival time between pleural effusion and pulmonary edema in cats with various cardiomyopathies.

Animals, Material And Methods: A total of 125 cats with CHF presenting as predominantly pleural effusion (n = 73) or pulmonary edema (n = 52) were included in this study. Medical records of cats presenting with CHF between 2013 and 2022 were evaluated retrospectively. Refractory CHF was defined as one requiring greater than 6 mg/kg/day of furosemide or introduction of torsemide. Signalment, underlying cardiomyopathy, the presence of pleural effusion or pulmonary edema, echocardiographic measurements at the time of CHF diagnosis, medications, comorbidities, time to refractory CHF, and survival time were recorded.

Results: The median survival time was significantly shorter (P=0.0002) for cats with pleural effusion (155 days; 95% confidence interval [CI]: 11-199 days) than for those with pulmonary edema (234 days; 95% CI: 177-509 days). Median time to refractory CHF was significantly shorter (P=0.0003) for cats with pleural effusion (44 days; 95 % CI: 32-67 days) than for those with pulmonary edema (133 days; 95% CI: 90-233 days). Pleural effusion significantly influenced time to refractory CHF (hazard ratio [HR]: 2.26; 95% CI: 1.16-4.62; P=0.022) and median survival time (HR: 1.87; 95% CI: 1.06-3.40; P=0.029) in the multivariable models.

Study Limitations: The limitations of this study were therapeutic recommendations not standardized and quantification of pleural effusion and fluid analysis not available for all cats.

Conclusions: In this study sample, cats with pleural effusion have a reduced time to refractory CHF and survival times compared to cats with pulmonary edema.