Management of acute heart failure in cats

2024 AAHA Fluid Therapy Guidelines for Dogs and Cats

Fluids are drugs used in veterinary patients capable of producing beneficial therapeutic or inadvertent harmful effects within the body's intravascular, interstitial, and intracellular fluid spaces. The individualized design of a fluid therapy plan requires careful patient assessment and targeted selection of proper fluid types, administration routes, and rates, along with adjustments during therapy tailored specifically as per the individual patient's fluid requirement and therapeutic response. Personalized fluid prescriptions and vigilant patient monitoring help avoid patient morbidity from body fluid deficiencies, fluid excess, and electrolyte derangements and support better patient outcomes. These guidelines provide an overview of fluid dynamics within the fluid spaces of the body, describe various types of fluids and their uses, and outline recommendations for fluid administration for resuscitation, rehydration, and maintenance purposes. The guidelines also outline approaches to fluid therapy for anesthetized patients and reiterate the recommendations of reduced fluid rates in this population of patients. Additionally, the guidelines include practical fluid therapy strategies for patients with various common disorders. The goal of these guidelines is to help veterinary professionals safely and effectively prescribe and administer fluid therapy for canine and feline patients.

Radiographic features of cardiogenic pulmonary oedema in cats with left-sided cardiac disease: 71 cases

OBJECTIVES

The aims of this study were to describe the radiographic features of cardiogenic pulmonary oedema (CPE) in a large group of cats with left-sided cardiac disease, and to determine the association between the radiographic features of CPE and the underlying cardiac disease.

METHODS

Thoracic radiographs of cats with CPE and echocardiographic evidence of left-sided cardiac disease and left atrial enlargement (LAE) were reviewed, and cardiac silhouette, pulmonary vessels and pulmonary parenchyma evaluation were performed. Interstitial and/or alveolar patterns were classified according to their distribution (ie, diffuse, multifocal or focal) and location (ie, craniodorsal, cranioventral, caudodorsal, caudoventral and perihilar). A Student's t-test and Mann-Whitney U-test, or the two-proportion z-test, were used to compare continuous or categorical variables, respectively, between cats affected by the two most represented cardiac diseases, namely hypertrophic cardiomyopathy (HCM) and restrictive cardiomyopathy (RCM).

RESULTS

Seventy-one cats were included; among them, 46 (64.7%) and 13 (18.3%) had presented for HCM and RCM, respectively. Subjective and objective cardiomegaly, and subjective and objective LAE were detected in 97.2% and 91.9% of cats and in 80.3% and 40.6% of cats, respectively. Pulmonary artery abnormalities, in particular caudal pulmonary artery dilation, were found in 77.5% of cats. Pulmonary artery to pulmonary vein ratio = 1 was found in 71.8% and 55% cats on right lateral and ventrodorsal or dorsoventral views, respectively. Interstitial (57.8%) and mixed interstitial-alveolar (38%) pattern, multifocal (84.5%) and symmetrical (75%) distribution with prevalent ventrocaudal (65.6% of cats) and ventrocranial (60.9% of cats) locations were most frequently observed. No difference was found for any of these radiographic features between cats with HCM and RCM.

CONCLUSIONS AND RELEVANCE

Moderate-to-severe cardiomegaly and LAE, caudal pulmonary artery and vein dilation, as well as a ventral, multifocal and symmetrical interstitial pulmonary pattern, were the main radiographic features of CPE in evaluated cats. Underlying cardiac disease did not influence the aforementioned radiographic features.

Reduced risk of arterial thromboembolism in cats with pleural effusion due to congestive heart failure

OBJECTIVES

The aim of the study was to determine whether cardiogenic pleural effusion in cats is associated with a lower risk of arterial thromboembolism (ATE) compared with cats with cardiac disease without evidence of pleural effusion.

METHODS

A cross-sectional study was conducted on owned cats with natural occurring cardiac diseases. Cats included were classified in three groups: those with cardiac disease but no evidence of congestive heart failure (CHF); those with evidence of cardiogenic pulmonary oedema; and those with evidence of cardiogenic pleural effusion. Prevalence of ATE was calculated and the variables analysed for an association with this outcome were the presence and type of CHF, sex and neuter status, age, breed, type of cardiac diseases and left atrial (LA) dimension. A multivariable logistic regression model was used to fit the association between ATE and these variables.

RESULTS

A total of 366 cats with cardiac disease met the inclusion criteria: 179 were included in the group with cardiac disease but no evidence of CHF, 66 in the group with evidence of cardiogenic pulmonary oedema and 121 in the group with evidence of cardiogenic pleural effusion. Prevalence of ATE (58/366 [15.8%]) was significantly different among groups (with no evidence of CHF, 28/179 [15.6%]; with evidence of cardiogenic pulmonary oedema, 22/66 [33.3%]; with evidence of cardiogenic pleural effusion, 8/121 [6.6%]; P <0.001). Cats with ATE had a significantly higher LA to aortic root ratio (2.30 ± 0.46) than those without ATE (2.04 ± 0.46; P <0.001). Multivariable logistic regression analysis indicated that the group with evidence of cardiogenic pleural effusion was associated with a lower risk of developing ATE compared with groups with cardiac disease but no evidence of CHF and with evidence of cardiogenic pulmonary oedema (P = 0.005 and P <0.001, respectively).

CONCLUSIONS AND RELEVANCE

Presence of cardiogenic pleural effusion is associated with a lower risk of developing ATE, while LA enlargement is a risk factor for ATE.

Prognostic Value of Neutrophil-to-Lymphocyte Ratio in Cats With Hypertrophic Cardiomyopathy

Objective

To assess the prognostic value of neutrophil-to-lymphocyte ratio (NLR) for cardiac death in cats with hypertrophic cardiomyopathy.

Study Design

Prospective observation study.

Animals

Ninety-six client-owned cats.

Methods

Complete blood count samples were collected from 38 healthy and 58 cats with hypertrophic cardiomyopathy (HCM), and the NLR ratios were analyzed. All cats had echocardiographic measurements performed on the same day as blood collection. Spearman rank correlation was used to assess the relationship between echocardiographic measurements and NLR. Long-term outcome data were obtained, and time to cardiac death and variables associated with cardiac death were analyzed using Kaplan–Meier survival curves and Cox proportional hazards models, respectively.

Results

The NLR was significantly higher in cats with confirmed congestive heart failure. When evaluating HCM patients, cats in the third NLR tertile had a significantly higher risk of cardiac death with a hazard ratio of 10.26 (95% CI: 1.84–57.14; p = 0.0001) when compared with that of patients in the first tertile. NLR was significantly associated with echocardiographic measures of left atrial size, left auricular function, the presence of left atrial spontaneous echo contrast (SEC), and thrombus formation.

Conclusions and Clinical Relevance

Increased NLR is a negative prognostic indicator in cats with HCM.

Clinical relevance of serum electrolytes in dogs and cats with acute heart failure: A retrospective study

Background

Hypochloremia is a strong negative prognostic factor in humans with congestive heart failure (CHF), but the implications of electrolyte abnormalities in small animals with acute CHF are unclear.

Objectives

To document electrolyte abnormalities present upon admission of small animals with acute CHF, and to assess the relationship between electrolyte concentrations and diuretic dose, duration of hospitalization and survival time.

Animals

Forty‐six dogs and 34 cats with first onset of acute CHF.

Methods

Retrospective study. The associations between electrolyte concentrations and diuretic doses were evaluated with Spearman rank correlation coefficients. Relationship with duration of hospitalization and survival were assessed by simple linear regression and Cox proportional hazard regression, respectively.

Results

The most commonly encountered electrolyte anomaly was hypochloremia observed in 24% (9/46 dogs and 10/34 cats) of cases. In dogs only, a significant negative correlation was identified between serum chloride concentrations at admission (median 113 mmol/L [97‐125]) and furosemide doses both at discharge (median 5.2 mg/kg/day [1.72‐9.57]; r = −0.59; P < .001) and at end‐stage heart failure (median 4.7 mg/kg/day [2.02‐7.28]; r = −0.62; P = .005). No significant hazard ratios were found for duration of hospitalization nor survival time for any of the electrolyte concentrations.

Conclusions and Clinical Importance

The observed association between serum chloride concentrations and diuretic doses suggests that hypochloremia could serve as a marker of disease severity and therapeutic response in dogs with acute CHF.

Effects of pimobendan in cats with hypertrophic cardiomyopathy and recent congestive heart failure: Results of a prospective, double-blind, randomized, nonpivotal, exploratory field study

Background

The benefits of pimobendan in the treatment of congestive heart failure (CHF) in cats with hypertrophic cardiomyopathy (HCM) have not been evaluated prospectively.

Hypothesis/Objectives

To investigate the effects of pimobendan in cats with HCM and recent CHF and to identify possible endpoints for a pivotal study. We hypothesized that pimobendan would be well‐tolerated and associated with improved outcome.

Animals

Eighty‐three cats with HCM and recently controlled CHF: 30 with and 53 without left ventricular outflow tract obstruction.

Methods

Prospective randomized placebo‐controlled double‐blind multicenter nonpivotal field study. Cats received either pimobendan (0.30 mg/kg q12h, n = 43), placebo (n = 39), or no medication (n = 1) together with furosemide (<10 mg/kg/d) with or without clopidogrel. The primary endpoint was a successful outcome (ie, completing the 180‐day study period without a dose escalation of furosemide).

Results

The proportion of cats in the full analysis set population with a successful outcome was not different between treatment groups (P = .75). For nonobstructive cats, the success rate was 32% in pimobendan‐treated cats versus 18.2% in the placebo group (odds ratio [OR], 2.12; 95% confidence interval [CI], 0.54‐8.34). For obstructive cats, the success rate was 28.6% and 60% in the pimobendan and placebo groups, respectively (OR, 0.27; 95% CI, 0.06‐1.26). No difference was found between treatments for the secondary endpoints of time to furosemide dose escalation or death (P = .89). Results were similar in the per‐protocol sets. Adverse events in both treatment groups were similar.

Conclusions and Clinical Importance

In this study of cats with HCM and recent CHF, no benefit of pimobendan on 180‐day outcome was identified.

Twenty-four-hour ambulatory (Holter) electrocardiographic findings in 13 cats with non-hypertrophic cardiomyopathy

Detection and characterisation of cardiac arrhythmias in cats with hypertrophic cardiomyopathy (HCM) has already been documented in various studies. However, similar studies have not been reported for other forms of feline cardiomyopathy. The clinical records of 13 client-owned cats diagnosed with restrictive cardiomyopathy (RCM), arrhythmogenic right ventricular cardiomyopathy (ARVC) and non-specific cardiomyopathy (NSCM) that underwent Holter recording at the time of diagnosis were reviewed retrospectively. Eight cats had signs of congestive heart failure at presentation, one cat had a history of recurrent syncope and the remaining four cats were asymptomatic. The average heart rate was 138 ± 22 (range 97-181) beats per minute (bpm) with the lowest value (97 bpm) recorded in a cat with third degree atrioventricular block (3-AVB) and the highest value (181 bpm) observed in a cat with atrial fibrillation (AF). The median number of ventricular ectopic beats (VEB) over 24 h was 2031 (338-8305), mostly represented by single isolated VPCs (803, 123-2221). Cardiac pauses were observed in three cats, with the longest pause lasting more than 6 s. A survival analysis was not performed due to the small number of cats and limited follow-up information. Holter recording revealed cardiac arrhythmias in all 13 cats, while 8/13 cats (61.5%) had an unremarkable resting electrocardiogram (ECG). The average daily heart rate in these cats did not appear affected by the presence of heart failure, although periods of sinus arrhythmia were absent in all individuals.

Successful management of ventricular fibrillation and ventricular tachycardia using defibrillation and intravenous amiodarone therapy in a cat

OBJECTIVE

To describe the successful management of ventricular fibrillation (VF) and ventricular tachycardia (VT) using cardiopulmonary resuscitation, including defibrillation, followed by continuous rate infusion of IV amiodarone, in a cat with cardiac arrest secondary to tachyarrhythmia.

CASE SUMMARY

A 12-year-old previously healthy neutered male Scottish Fold cat presented following an acute episode of collapse. Initial physical examination revealed severe tachycardia and cardiovascular collapse. Within a few minutes after arrival, the cat experienced cardiopulmonary arrest. Electrocardiographic assessment was suggestive of VF, and CPR was initiated, including 2 rounds of defibrillation (2 joule/kg each), resulting in return of spontaneous circulation with sustained VT. After procainamide and lidocaine failed to result in conversion to normal sinus rhythm (NSR), continuous IV amiodarone therapy was initiated, and NSR was achieved. Echocardiography demonstrated severe systolic dysfunction, and tachycardia-induced cardiomyopathy (TICM) secondary to chronic VT was suspected; however, dilated cardiomyopathy (DCM) or end-stage hypertrophic cardiomyopathy could not be ruled out. The patient was discharged the following day with oral amiodarone and pimobendan. During a recheck examination performed 7 months later the cat was in NSR, with no direct evidence of long-term amiodarone adverse effects. The cat died acutely at home 8 months after discharge.

NEW OR UNIQUE INFORMATION PROVIDED

This report is the first to describe the successful use of IV amiodarone in a cat to manage sustained VT following CPR.

Pharmacokinetics of furosemide after intravenous, oral and transdermal administration to cats

OBJECTIVES

The aim of this study was to determine the pharmacokinetics of furosemide in cats following intravenous (IV), oral and transdermal administration.

METHODS

This study used six healthy adult cats in a three-phase design to compare plasma furosemide concentrations in cats that received one IV 2 mg/kg dose of furosemide, one oral 2 mg/kg dose of furosemide and 3 days of q12h dosing with 2 mg/kg furosemide transdermally applied to the ear pinna.

RESULTS

After IV administration the elimination half-life was (mean and coefficient of variation) 2.25 h (72%), systemic clearance was 149 ml/kg/h (27.4%) and volume of distribution was 227 ml/kg (22%). After oral administration the terminal half-life was 1.2 h (18.7%), peak concentration was 3.4 μg/ml (51.7%) and bioavailability was 48.4%. The transdermal plasma concentrations were undetectable or very low at most time points, and pharmacokinetics were not determined from the transdermal dose.

CONCLUSIONS AND RELEVANCE

Furosemide was rapidly eliminated in cats after oral and IV administration and is probably best administered orally at least q12h in cats with heart failure. The oral dose absorbed was approximately 50%, but the absorption from transdermal administration was negligible.

Detection of intra-cardiac thrombi and congestive heart failure in cats using computed tomographic angiography

Arterial thromboembolism is a life-threatening condition in cats most commonly secondary to cardiac disease. Echocardiography is the reference standard to evaluate for presence of a thrombus. In humans, computed tomographic (CT) angiography is becoming widely used to detect left atrial thrombi precluding the use of sedation. The purpose of this prospective, controlled, methods comparison pilot study was threefold: (1) describe new CT angiography protocol used in awake cats with cardiac disease and congestive heart failure; (2) determine accuracy of continuous and dynamic acquisition CT angiography to identify and characterize cardiac thrombi from spontaneous echocardiographic contrast using transthoracic echocardiography as our reference standard; (3) identify known negative prognostic factors and comorbidities of the thorax that CT angiography may provide that complement or supersede echocardiographic examination. Fourteen cats with heart disease were recruited; 7 with thrombi and 7 with spontaneous echocardiographic contrast. Echocardiography and awake CT angiography were performed using a microdose of contrast. Six of 7 thrombi were identified on CT angiography as filling defects by at least one reviewer within the left auricle (n = 6) and right heart (n = 1). Highest sensitivity (71.4%) was in continuous phase and highest specificity (85.7%) was in dynamic studies with fair to moderate interobserver agreement (0.38 and 0.44). CT angiography identified prognostic cardiac information (left atrial enlargement, congestive heart failure, arterial thromboembolism) and comorbidities (suspected idiopathic pulmonary fibrosis, asthma). This study indicates CT angiography can readily identify cardiac thrombi, important prognostic information and comorbidities, and can be safely performed in cats with cardiac disease and congestive heart failure.