Prediction of first onset of congestive heart failure in dogs with degenerative mitral valve disease: the PREDICT cohort study

Longitudinal analysis of echocardiographic and cardiac biomarker variables in dogs with atrial fibrillation: The optimal rate control in dogs with atrial fibrillation II study

BACKGROUND

Rate control (RC; meanHRHolter ≤ 125 bpm) increases survival in dogs with atrial fibrillation (AF). The mechanisms remain unclear.

HYPOTHESIS/OBJECTIVES

Investigate echocardiographic and biomarker differences between RC and non-RC (NRC) dogs. Determine if changes post-anti-arrhythmic drugs (AAD) predict successful RC in subsequent Holter monitoring. Evaluate if early vs late RC affects survival.

ANIMALS

Fifty-two dogs with AF.

METHODS

Holter-derived mean heart rate, echocardiographic and biomarker variables from dogs receiving AAD were analyzed prospectively at each re-evaluation and grouped into RC or NRC. The primary endpoint was successful RC. Between group comparisons of absolute values, magnitude of change from admission to re-evaluations and end of study were performed using Mann-Whitney tests or unpaired t-tests. Logistic regression explored variables associated with inability to achieve RC at subsequent visits. Kaplan-Meier survival analysis was used to compare survival time of early vs late RC.

RESULTS

At visit 2, 11/52 dogs were RC; at visit 3, 14/52 were RC; and at visit 4, 4/52 were RC. At the end of study, 25/52 remained NRC. At visit 2, both groups had increased cardiac dimensions, but NRC dogs had larger dimensions; biomarkers did not differ. At the end of study, RC showed decreased cardiac dimensions and end-terminal pro-brain natriuretic peptide (NT-proBNP) compared with NRC. No variables were useful at predicting RC success in subsequent visits. Survival analysis found no differences between early vs late RC.

CONCLUSIONS AND CLINICAL IMPORTANCE

The RC dogs had decreased cardiac dimensions and NT-proBNP, suggesting HR-mediated reverse-remodeling might benefit survival, even with delayed RC achievement. Pursuit of RC is crucial despite initial failures.

RNA sequencing provides novel insights into the pathogenesis of naturally occurring myxomatous mitral valve disease stage B1 in beagle dogs

Myxomatous mitral valve disease (MMVD) is the most common cardiovascular disorder in dogs with a high prevalence, accounting for approximately 75% of all canine heart disease cases. MMVD is a complex disease and shows variable progression from mild valve leakage to severe regurgitation, potentially leading to heart failure. However, the molecular mechanisms and age-related changes that govern disease progression, especially at the early stage (B1) before the development of discernable clinical signs, remain poorly understood. In this prospective study, we aimed to compare gene expression differences between blood samples of aged beagle dogs with stage B1 MMVD and those of healthy controls using RNA sequencing. Clinical evaluation was also conducted, which revealed minimal differences in radiographic and echocardiographic measurements despite distinct biomarker variations between the two groups. Comparative transcriptomics revealed differentially expressed genes associated with extracellular matrix remodeling, prostaglandin metabolism, immune modulation, and interferon-related pathways, which bear functional relevance for MMVD. In particular, the top 10 over- and under-expressed genes represent promising candidates for influencing pathogenic changes in MMVD stage B1. Our research findings, which include identified variations in clinical markers and gene expression, enhance our understanding of MMVD. Furthermore, they underscore the need for further research into early diagnosis and treatment strategies, as, to the best of our knowledge, no prior studies have explored the precise molecular mechanisms of stage B1 in MMVD through total RNA sequencing.

Retrospective evaluation of the utility of shock index to determine the presence of congestive heart failure in dogs with myxomatous mitral valve disease (2019-2021): 98 cases

OBJECTIVES

To calculate the shock index (SI) in dogs with myxomatous mitral valve disease (MMVD) and to evaluate its use to predict the presence of congestive heart failure (CHF).

DESIGN

Retrospective study.

SETTING

Small animal university veterinary teaching hospital.

ANIMALS

Ninety-eight dogs with MMVD and 20 healthy dogs as part of a control group.

INTERVENTIONS

Heart rate (HR) and systolic blood pressure (SBP) were recorded, and SI was calculated by dividing HR by SBP for each dog.

MEASUREMENTS AND MAIN RESULTS

The mean (SD) HR, SBP, and SI were 123/min (32.6), 147 mm Hg (21.5), and 0.86 (0.3), respectively, for dogs with MMVD and 98/min (20.9), 145 mm Hg (18.7), and 0.68 (0.13), respectively, for control dogs. Dogs with MMVD had a significantly higher HR compared with control dogs (P < 0.01), and an elevation in HR was seen as the severity of MMVD increased. Dogs in stage B2 and C/D MMVD had a significantly higher SI value compared with control dogs (P = 0.04 and P < 0.01, respectively). SI was significantly higher in dogs in stage C/D MMVD compared with dogs in stage B2 MMVD (P < 0.01). Ten of 98 (10%) dogs had an arrhythmia. HR, SBP, and SI were not significantly different between dogs with and without arrhythmias (P = 0.13, P = 0.57, and P = 0.07, respectively), but significantly more dogs with CHF had an arrhythmia (P = 0.01). SI (area under the curve [AUC]: 0.98) and HR (AUC: 0.95) were excellent indicators for the presence of CHF. An optimal SI cutoff value ≥1.1 had 92% sensitivity and 95% specificity for predicting the presence of CHF, and an optimal HR cutoff value of ≥157/min had 92% sensitivity and 93% specificity for the prediction of CHF.

CONCLUSIONS

When there are compatible clinical signs, SI values ≥1.1 may suggest the presence of CHF in dogs with MMVD.

Efficacy of a mitral regurgitation severity index to predict long-term outcome in dogs with myxomatous mitral valve disease

BACKGROUND

Predicting progression of myxomatous mitral valve disease (MMVD) in dogs can be challenging.

HYPOTHESIS/OBJECTIVES

The mitral regurgitation severity index (MRSI) will predict time to congestive heart failure (CHF) and all-cause death in dogs with MMVD.

ANIMALS

Eight hundred sixty-nine client-owned dogs.

METHODS

Retrospective study pooling data from 4 previous samples including dogs with MMVD stage B2 or C. MRSI was calculated as: (heart rate [HR]/120) × left atrium-to-aorta ratio (LA:Ao) × (age in years/10) × 100. Alternative MRSI formulas substituting radiographic measures of left atrial size were also calculated. Cox proportional hazard modeling and time-dependent receiver-operator characteristic curves quantified prognostic performance.

RESULTS

For Stage B2 pooled samples, MRSI > 156 was predictive of time to CHF (median 407 vs 1404 days; area under the curve [AUC] 0.68; hazard ratio 3.02 [95% CI 1.9-4.9]; P < .001). MRSI > 173 was predictive of all-cause death (median survival 868 vs 1843 days; AUC 0.64; hazard ratio 4.26 [95% CI 2.4-7.5]; P < .001). MRSI showed superior predictive value compared to the individual variables of HR, LA:Ao, and age. Variations of the MRSI equation substituting radiographic vertebral left atrial size for LA:Ao were also significantly predictive of outcome in stage B2. MRSI was not consistently predictive of outcome in Stage C.

CONCLUSIONS AND CLINICAL IMPORTANCE

MRSI was predictive of outcome (onset of CHF and all-cause death) in MMVD Stage B2, demonstrating utility as a useful prognostic tool. Echocardiographic LA:Ao can be effectively replaced by radiographically determined LA size in the MRSI formula.

The heart to single vertebra ratio: A new objective method for radiographic assessment of cardiac silhouette size in dogs

Vertebral heart size (VHS) is widely determined in clinical practice as an objective method to assess the cardiac silhouette dimensions. However, a key limitation is that it is difficult to determine VHS in dogs with vertebral alterations. This retrospective, method comparison, observer agreement study sought to overcome this limitation by using the heart-to-single vertebra ratio (HSVR), by evaluating the level of agreement between VHS and HSVR, as well as the intra- and inter-observer agreement for HSVR. Three independent observers retrospectively evaluated thoracic radiographs obtained over a set time period. Exclusion criteria were the presence of alterations of the thoracic spine and the inability to clearly outline the cardiac silhouette. The lengths of the vertebral bodies, from the fourth to eighth thoracic vertebra, and VHS were measured on each radiograph. The HSVR was calculated by dividing the sum of the cardiac long and short axes by the length of each vertebral body. Eighty dogs of different breeds were included in the final analysis. Lin's concordance correlation coefficients revealed strong correlations between VHS and HSVR (0.91-0.96), and the Bland-Altman plots showed low bias (0.01-0.2) between the methods. The mean absolute errors indicated low average magnitudes of error (0.11-0.28). The intraclass correlation coefficients showed good to excellent inter-observer (0.87-0.92; P = 0.000) and intra-observer (0.87-0.99; P < .001) agreement. In the authors' opinion, this new method, which is less time consuming and more objective, could offer a valuable alternative to VHS.

Optimal rate control in dogs with atrial fibrillation-ORCA study-Multicenter prospective observational study: Prognostic impact and predictors of rate control

BACKGROUND

The optimal heart rate (HR) in dogs with atrial fibrillation (AF) is unknown. Impact of HR on survival needs elucidation.

HYPOTHESIS/OBJECTIVES

Dogs with a 24 hours Holter-derived meanHR ≤125 beats per minute (bpm; rate controlled) survive longer than dogs with higher meanHR. We further aimed to determine which variables predict ability to achieving rate control.

ANIMALS

Sixty dogs with AF.

METHODS

Holter-derived meanHR, clinical, echocardiographic, and biomarker variables were analyzed prospectively. Survival was recorded from time of rate control, with all-cause mortality as primary endpoint. Cox proportional hazards analysis identified variables independently associated with survival; Kaplan-Meier survival analysis estimated the median survival time of dogs with meanHR ≤125 bpm vs >125 bpm. Logistic regression explored baseline variables associated with inability to achieve rate control.

RESULTS

Structural heart disease was present in 56/60 dogs, 50/60 had congestive heart failure, and 45/60 died. Median time to all-cause death was 160 days (range, 88-303 days), dogs with meanHR >125 bpm (n = 27) lived 33 days (95% confidence interval [CI], 15-141 days), dogs with meanHR ≤125 bpm (n = 33) lived 608 days (95% CI, 155-880 days; P < .0001). Congenital heart disease and N-terminal pro-B-type natriuretic peptide were independently associated with higher risk of death (P < .01 and <.0001, respectively) whereas meanHR ≤125 bpm decreased the risk of death (P < .001). Increased left atrial size, increased C-reactive protein concentration and lower blood pressure at admission were associated with failure to achieve rate control.

CONCLUSIONS AND CLINICAL IMPORTANCE

Rate control affects survival; an optimal target meanHR <125 bpm should be sought in dogs with AF. Baseline patient variables can help predict if rate control is achievable.

Prognostic relevance of left cardiac enlargement in dogs with preclinical myxomatous mitral valve disease

INTRODUCTION

According to the most recent consensus guidelines on canine myxomatous mitral valve disease (MMVD), dogs with only left atrial enlargement (LAE) or left ventricular enlargement are classified as stage B1. The concomitant presence of LAE and left ventricular enlargement is needed to be classified as stage B2. The primary aim of the study was to evaluate the prognosis in stage B1 and stage B2 according to the revised definition. The secondary aim was to assess the prognostic relevance of LAE in stage B1.

ANIMALS

A total of 440 dogs with MMVD, 276 in stage B1 and 164 in stage B2.

MATERIALS AND METHODS

Retrospective and observational study. The left atrium-to-aorta ratio and the left ventricular end-diastolic diameter normalized were used to define cardiac dimensions. The long-term outcome was assessed by telephone interviews with owners and referring vets. Both cardiac-related and all-cause mortality were evaluated.

RESULTS

Stage B1 dogs had a longer median survival time than stage B2, considering both cardiac-related death (2344 vs. 1341 days; P<0.001) and all-cause mortality (1832 vs. 855 days; P<0.001). Age, left atrium-to-aorta ratio, and the left ventricular end-diastolic diameter normalized were independent predictors of cardiac-related death and all-cause mortality. Among stage B1, dogs with LAE lived shorter than those without LAE (1183 vs. 1882 days; P=0.005) considering all-cause mortality.

DISCUSSION AND CONCLUSIONS

Stage B1 dogs lived longer than stage B2 dogs. Among stage B1, LAE had prognostic relevance considering all-cause mortality. This finding could add useful prognostic information in the management of preclinical MMVD.

Comparison of different radiographic scores with associated echocardiographic measurements and prediction of heart enlargement in dogs with and without myxomatous mitral valve disease

INTRODUCTION

Staging of myxomatous mitral valve disease (MMVD) requires an echocardiographic examination along with thoracic radiographs. The aims of this study were to calculate mean values for radiographic scores vertebral heart size (VHS), left atrial width (LA_Width), radiographic left atrial dimension (RLAD), and vertebral left atrial size (VLAS) in conventional and grayscale inverted images in healthy dogs and dogs with different stages of MMVD, and to find cutoff values for a stage assignment.

ANIMALS

One hundred fifty dogs in different stages of MMVD and 50 unaffected dogs were evaluated.

METHODS

Radiographic scores, echocardiographic left atrium-to-aorta ratio and normalized left ventricular internal dimension at end-diastole, and results of a clinical examination were obtained. Analyses were performed to evaluate the correlation between radiographic scores and echocardiographic values, to determine cutoff values for a radiographic stage assignment, and to compare measurements in conventional and inverted radiographs.

RESULTS

After excluding breed-specific higher VHS, the means of VHS, LA_Width, RLAD, and VLAS were similar in the control group and stage B1. All radiographic scores increased in stages B2 and C. The cutoff values identifying heart enlargement, and therefore differentiating stages B1 and B2, were 11.0 for VHS, 1.8 for LA_Width, 2.0 for RLAD, and 2.3 for VLAS. Besides RLAD, scores were similar in conventional and inverted radiographs.

CONCLUSION

Cutoff values for the different radiographic scores for stage assignment were calculated. Radiographic cardiac scores using either conventional or inverted grayscale could be a tool to differentiate between different stages of MMVD when echocardiography is unavailable.

Evaluation of plasma N-terminal pro-B-type natriuretic peptide levels in healthy North American Salukis with normal echocardiographic measurements

Measurement of N‐terminal pro‐B‐type natriuretic peptide (NT-proBNP) levels has been shown to have clinical significance for diagnosis and management of heart disease in dogs. Evaluation of current reference limits for specific breeds is necessary to ensure the test can accurately distinguish between healthy and diseased animals. The objective of this study is to evaluate the adequacy of currently established NT-proBNP reference limits for clinical use in healthy Salukis. Cardiac health of 33 clinically healthy Salukis was evaluated via echocardiography using available breed standards. Plasma concentrations of NT-proBNP were measured using a commercially available assay. A one-sided 97.5% upper reference limit for the NT-proBNP concentrations was calculated using non-parametric percentile method. The 97.5% upper reference limit was 769 pmol/L (90% CI, 547–1214 pmol/L) for the study dogs. This upper reference limit was within the currently established non-breed specific NT-proBNP upper reference limit of 900 pmol/L. No relationship between sex, age, or body weight on plasma levels of NT-proBNP was noted. Results of this study supports the use of currently available non-breed specific NT-proBNP cut-off values for clinical evaluation of healthy Salukis.

Clinical findings associated with N-terminal pro-B-type natriuretic peptide measurement in dogs and cats attending first opinion veterinary practices

BACKGROUND

Clinical findings associated with N-terminal pro-B-type natriuretic peptide (NT-proBNP) measurement in dogs and cats in primary practice, and their relevance to published measurement indications, have not been described.

METHODS

Using electronic health record data collected by the Small Animal Veterinary Surveillance Network, appointments in which NT-proBNP was measured were identified using keyword-based text filtering. For these appointments, clinical findings were manually identified from each patient's clinical narrative (CN) and their frequencies described.

RESULTS

CNs of 3510 appointments (357 dogs and 257 cats) from 99practices were evaluated. The most frequently recorded clinical findings in dogs were: heart murmur (n = 147, 41.2% (95% confidence interval (CI) = 36.1%-46.3%), coughing (n = 83, 23.2% (95% CI = 18.8%-27.6%)) and panting (n = 58, 16.2% (95% CI = 12.4%-20.0%)) and in cats: heart murmur (n = 143, 55.6% (95% CI = 49.5%-61.7%)), suspected thromboembolism (n = 88, 34.2% (95% CI = 28.4%-40.0%)) and weight loss (n = 53, 20.6% (95% CI = 15.7%-25.5%)). Dyspnoea and tachypnoea were infrequently reported in dogs (n = 29, 8.1% (95% CI = 5.3%-10.9%) and n = 21, 5.9% (95% CI = 3.5%-8.3%), respectively) and cats (n = 26, 10.1% (95% CI = 6.4%-13.8%) and n = 36, 14.0% (95% CI = 9.8%-18.2%), respectively).

CONCLUSION

Clinical findings referable to cardiac disease were recorded contemporaneously with NT-proBNP measurement and suggested both published and other indications (coughing (in dogs and cats), and serial measurements and thromboembolism (in cats)) for testing.

The predictive value of clinical, radiographic, echocardiographic variables and cardiac biomarkers for assessing risk of the onset of heart failure or cardiac death in dogs with preclinical myxomatous mitral valve disease enrolled in the DELAY study

OBJECTIVES

To identify the predictive value on time to onset of heart failure (HF) or cardiac death of clinical, radiographic, and echocardiographic variables, as well as cardiac biomarkers N-terminal pro brain natriuretic peptide (NT-proBNP) and cardiac troponin I in dogs with preclinical myxomatous mitral valve disease (MMVD).

ANIMALS

One hundred sixty-eight dogs with preclinical MMVD and left atrium to aortic root ratio ≥1.6 (LA:Ao) and normalized left ventricular end-diastolic diameter ≥1.7 were included.

METHODS

Prospective, randomized, multicenter, single-blinded, placebo-controlled study. Clinical, radiographic, echocardiographic variables and plasma cardiac biomarkers concentrations were compared at different time points. Using receiving operating curves analysis, best cutoff for selected variables was identified and the risk to develop the study endpoint at six-month intervals was calculated.

RESULTS

Left atrial to aortic root ratio >2.1 (hazard ratio [HR] 3.2, 95% confidence interval [95% CI] 1.9-5.6), normalized left ventricular end-diastolic diameter > 1.9 (HR: 6.3; 95% CI: 3.3-11.8), early transmitral peak velocity (E peak) > 1 m/sec (HR: 3.9; 95% CI: 2.3-6.7), and NT-proBNP > 1500 ρmol/L (HR: 5.7; 95% CI: 3.3-9.5) were associated with increased risk of HF or cardiac death. The best fit model to predict the risk to reach the endpoint was represented by the plasma NT-proBNP concentrations adjusted for LA:Ao and E peak.

CONCLUSIONS

Logistic and survival models including echocardiographic variables and NT-proBNP can be used to identify dogs with preclinical MMVD at higher risk to develop HF or cardiac death.

The Mitral INsufficiency Echocardiographic score: A severity classification of myxomatous mitral valve disease in dogs

Background

There is no commonly shared severity score for myxomatous mitral valve disease (MMVD) based on routinely acquired echocardiographic variables.

Hypothesis/Objectives

To propose an easy‐to‐use echocardiographic classification of severity of MMVD in dogs.

Animals

Five hundred and sixty dogs with MMVD.

Methods

This was a retrospective, multicenter, observational study. The proposed Mitral INsufficiency Echocardiographic (MINE) score was based on 4 echocardiographic variables: left atrium‐to‐aorta ratio, left ventricular end‐diastolic diameter normalized for body weight, fractional shortening, and E‐wave transmitral peak velocity. Specific echocardiographic cutoffs were defined based on previous prognostic studies on MMVD, and severity scores were assigned as follows: mild (score: 4‐5), moderate (score: 6‐7), severe (score: 8‐12), late stage (score: 13‐14).

Results

Median survival time was significantly different (P < .05) between the proposed severity classes: mild (2344 days, 95% confidence interval [CI] 1877‐2810 days), moderate (1882 days, 95% CI 1341‐2434 days), severe (623 days, 95% CI 432‐710 days), and late stage (157 days, 95% CI 53‐257 days). A MINE score >8 was predictive of cardiac death (area under the curve = 0.85; P < .0001; sensitivity 87%, specificity 73%). In the multivariable analysis, all the echocardiographic variables of the MINE score were independent predictors of death because of heart disease (P < .001).

Conclusions and Clinical Importance

The MINE score is a new easy‐to‐use echocardiographic classification of severity of MMVD, which has been proven to be clinically effective as it is associated with survival. This classification provides prognostic information and could be useful for an objective echocardiographic assessment of MMVD.

Radiographic quantification of left atrial size in dogs with myxomatous mitral valve disease

Background

In the absence of echocardiography, identification of cardiomegaly via thoracic radiography is a necessary criterion for classification of disease severity in dogs with myxomatous mitral valve disease (MMVD).

Objective

Modified‐vertebral left atrial size (M‐VLAS) facilitates objective radiographic assessment of the left atrium (LA) in 2 dimensions and identifies LA enlargement more accurately than existing methods.

Animals

Sixty‐four dogs with various stages of MMVD and 6 control healthy dogs.

Methods

Retrospective case–control study. Medical records were searched for dogs with varying severity of MMVD. Modified‐vertebral left atrial size, vertebral left atrial size (VLAS), vertebral heart size (VHS), and radiographic left atrial dimension (RLAD) were measured from thoracic radiographs and compared with echocardiographically derived measurements.

Results

Positive correlation to LA/Ao was identified for M‐VLAS (r = 0.77, P < .001), VLAS (r = 0.76, P < .001), RLAD (r = 0.75, P < .001), and VHS (r = 0.67, P < .001). Receiver operating characteristic analyzes provided an area under the curve of 0.97 (95% CI, 0.94‐1.00) for M‐VLAS, which was superior to VHS (0.90, 95% CI, 0.94‐1.00, P = .03) in identifying dogs with LA/Ao ≥1.6. A cut‐off value of ≥3.4 vertebrae using M‐VLAS provided 92.7% sensitivity and 93.1% specificity in predicting LA enlargement.

Conclusions and clinical importance

M‐VLAS, which is superior to VHS, offers an accurate and repeatable way to radiographically identify LA enlargement in dogs with MMVD.

Evaluation of radiographic predictors of left heart enlargement in dogs with known or suspected cardiovascular disease

Radiographic assessment of heart size is important for clinical management of dogs with cardiovascular disease (CVDz). We sought to compare the ability of vertebral heart size (VHS), vertebral left atrial size (VLAS), and radiologists' assessment of left atrial size (RadLAE) to predict echocardiographic left atrial size (EchoLAE), an important marker of left heart disease severity. We also compared the ability of VHS and VLAS to predict echocardiographic criteria for ACVIM stage B2 (EchoB2) in dogs with myxomatous mitral valve disease (MMVD). This prospective observational study enrolled 183 dogs with known or suspected CVDz that had an echocardiographic examination and thoracic radiographs obtained within 24 h. Compared to increased VHS, VLAS >2.3 was a more accurate predictor of EchoLAE (P = .002). VLAS >2.3 and RadLAE (both P <.0001) were independently associated with EchoLAE but VHS was not (P = .45). Optimal cutoffs for VLAS and VHS to predict EchoLAE were >2.3 vertebrae (sensitivity [Sn] = 90.3%, specificity [Sp] = 73.6%) and >11.1 vertebrae (Sn = 75.8%, Sp = 76.0%), respectively. Diagnostic accuracy of VLAS (AUC 0.84, 95% CI 0.73-0.92) and VHS (AUC 0.78, 95% CI 0.66-0.88) to predict EchoB2 in dogs with subclinical MMVD (n = 64) were not significantly different (P = .17). Results demonstrate that VLAS and RadLAE were superior indicators of EchoLAE compared to VHS in dogs with known or suspected CVDz. Both VLAS and VHS are useful predictors of EchoB2 in dogs with subclinical MMVD. When echocardiography is unavailable, VLAS represents a useful radiographic measurement to aid clinical management of dogs with known or suspected CVDz.

Preliminary Outcome of a Novel Edge-to-Edge Closure Device to Manage Mitral Regurgitation in Dogs

Background: Veterinary management of mitral valve regurgitation due to mxyomatous valve disease in dogs is limited to medical treatments, which only postpones the onset of congestive heart failure or alleviates clinical symptoms. Most surgical procedures to manage this condition in humans require cardiopulmonary bypass and have a high risk of complications.

Animals: Eight dogs with naturally occurring mitral valve regurgitation.

Methods: Prospective observational study. All dogs were treated with a novel edge-to-edge transcatheter device named ValveClamp. The total surgical procedural time and total catheterization time were recorded. Echocardiographic variables measured pre- and post-procedure were compared using Wilcoxin-signed rank test with a P < 0.05 considered significant. Data were expressed as median and interquartile range and absolute numbers and percentages.

Results: The procedural success rate was 100% and all the dogs survived without complications. The median (interquartile range) total surgical procedural time was 86.5 (76–96.2) minutes and catheterization time was 23.5 (22–33.8) minutes. Echocardiography revealed a significant reduction in mitral regurgitation severity in all dogs following the procedure based on both a reduced mitral regurgitant maximum jet area (P = 0.012) and a reduced mitral regurgitant maximum jet area to left atrial area (P = 0.018).

Conclusion: The ValveClamp device is effective at reducing the severity of mitral regurgitation in dogs with naturally occurring myxomatous valve disease.

Mitral valve dysplasia in eight English Springer Spaniels

INTRODUCTION

To describe the signalment, physical examination, and echocardiographic findings of a series of English Springer Spaniels (ESSs) diagnosed with congenital mitral valve dysplasia (MD).

ANIMALS

Eight client-owned ESSs with congenital MD referred for murmur investigation and/or suspected congestive heart failure (CHF).

MATERIALS AND METHODS

Retrospective case series. Medical records and echocardiograms were reviewed to collect relevant data. Echocardiograms were assessed for the following abnormalities consistent with MD: thickened valve leaflets or leaflet tips, a 'hockey stick' appearance to the valve leaflets, abnormal length of one leaflet with respect to the other, and tethering of one or both leaflets to the papillary muscles.

RESULTS

All eight dogs showed the typical echocardiographic lesions associated with MD: thickened leaflet tips (5/8), 'hockey stick' appearance (5/8), elongated anterior leaflet (4/8), tethering of one or both leaflets (7/8). Seven of the eight dogs presented in CHF. Six of the eight dogs had left ventricular dilation in both systole and diastole. Two of the eight dogs had reduced systolic function as assessed by ejection fraction/fractional shortening; however end-systolic volume index was increased in 6/8 dogs. Two dogs subsequently developed atrial fibrillation.

CONCLUSIONS

Congenital MD should be considered in ESSs with a left-sided apical systolic murmur, particularly in younger dogs. The valve changes seen are similar to those reported in other breeds with MD (thickened leaflet tips, hockey stick appearance to open leaflet tips, abnormal leaflet tethering, abnormally shaped leaflets) and may result in marked remodeling and CHF.

Interobserver variability of radiographic methods for the evaluation of left atrial size in dogs

The objectives of this retrospective, observer agreement study were to (a) test variability of radiographic left atrial dimension (RLAD) and vertebral left atrial size (VLAS) measurements among observers with different levels of expertise in thoracic radiology and cardiology, (b) assess whether one method is better than the other in detecting left atrial enlargement (LAE), and (c) assess the agreement among RLAD, VLAS, and American College of Veterinary Internal Medicine (ACVIM) classes. Seventy-four dogs (eight healthy and 66 with mitral valve disease) with thoracic radiographs and echocardiography performed on the same day were reviewed. Thirty showed echocardiographic LAE. Left atrial dimension was quantified using RLAD and VLAS by six different operators with three levels of clinical experience in veterinary cardiology/radiology. Vertebral heart score and fourth thoracic vertebra (T4) were also measured. Differences in T4, vertebral heart score (VHS), RLAD, and VLAS measurements were found among six operators and among the three levels of clinical expertise as well as between veterinary cardiology readers and veterinary radiology readers (P < .05). The area under the receiver operating characteristic (AUC) curve for VHS showed good performances for all observers and level and type of expertise; the AUC for RLAD and VLAS was suboptimal only for the radiology student. Our RLAD and VLAS cutoffs (1.9 and 2.43 v, respectively) were better related to qualitative radiographic than quantitative echocardiographic LAE evaluation. Radiographic LA dimension and VLAS showed an increase proportional to the worsening of the ACVIM class. In conclusion, these results allow us to affirm that RLAD and VLAS are reproducible measurements for detecting LAE. Better performances are associated with clinical expertise and background.

Reproducibility of echocardiographic indices of left atrial size in dogs with subclinical myxomatous mitral valve disease

Background

Reliability of echocardiographic measurements of left atrial (LA) size, an important marker of disease severity, has not been reported in dogs with myxomatous mitral valve disease (MMVD).

Objectives

To define and compare reliability of left atrial dimension/diameter (LAD), LAD indexed to aortic valve diameter (LAD/AoD), left atrium‐to‐aortic root ratio (LA/Ao), left atrial volume acquired from a right parasternal long‐axis (LAV^RPLx), and left apical view (LAV^LAP) in dogs with subclinical MMVD.

Animals

Nine dogs with subclinical MMVD.

Methods

Prospective reproducibility study. Dogs underwent 12 echocardiographic examinations by 2 operators on the mornings and afternoons of 3 nonconsecutive days within 1 week. Reliability (measurement variability) was quantified using coefficients of variation (CV) and 95% repeatability/reproducibility coefficients (95% RC). A mixed‐model analysis of variance (ANOVA) was used to determine if time of day, day, and operator were significant sources of variability for each index.

Results

Linear measurements (LAD, LAD/AoD, and LA/Ao) exhibited less within‐day, between‐day, and interoperator variability (CVs, 3.9%‐12.5%) than did volume estimate measurements (LAV^RPLx and LAV^LAP; CVs, 11.8%‐17.9%). Of the linear measurements, LA/Ao exhibited greater variability (CVs, 9.9%‐12.5%) compared to LAD and LAD/AoD (CVs, 3.9%‐4.9%). Operator was a significant (P = .005) source of variability for LA/Ao.

Conclusions and Clinical Importance

Compared to other linear measurements, LA/Ao was the least reproducible and most dependent on operator. The 95% RC for each LA size index are provided to help identify clinically relevant changes (beyond intraoperator or interoperator variability) during serial echocardiographic examinations of dogs with subclinical MMVD.

Temporal changes in clinical and radiographic variables in dogs with preclinical myxomatous mitral valve disease: The EPIC study

Background

The Evaluation of pimobendan in dogs with cardiomegaly caused by preclinical myxomatous mitral valve disease (EPIC) study monitored dogs with myxomatous mitral valve disease (MMVD) as they developed congestive heart failure (CHF).

Objectives

To describe the changes in clinical and radiographic variables occurring as dogs with MMVD and cardiomegaly develop CHF, compared to similar dogs that do not develop CHF.

Animals

One hundred and thirty‐five, and 73 dogs that did or did not develop CHF, respectively.

Materials and methods

The following variables were evaluated in 2 groups of dogs (dogs that did or did not develop CHF): Heart rate (HR), clinic respiratory rate (RR), home‐measured resting respiratory rate (RRR), rectal temperature (RT), body weight (BW), and vertebral heart sum (VHS). Absolute value and rate of change of each variable were calculated for each day a dog was in study. Daily means were calculated and plotted against time. The onset of CHF or last visit before leaving the study were set as reference time points.

Results

The most extreme values and rate of change occurred in variables immediately before onset of CHF. Vertebral heart sum increased earliest. Heart rate, RR, and RRR also increased. Rectal temperature and BW decreased. Increases in RR and RRR were most extreme and occurred immediately before CHF.

Conclusions and Clinical Importance

Dogs with MMVD and cardiomegaly experience increases in HR, RR, RRR, and VHS, and decreases in BW and RT as they develop CHF. The variables with highest absolute change and rate of change were RR and RRR. These findings reinforce the value of RR and RRR as indicators of impending or incipient CHF.

DELay of Appearance of sYmptoms of Canine Degenerative Mitral Valve Disease Treated with Spironolactone and Benazepril: the DELAY Study

INTRODUCTION

Efficacy of renin-angiotensin-aldosterone system (RAAS) blockade using angiotensin-converting enzyme inhibitors (ACEi) in dogs with preclinical myxomatous mitral valve disease (MMVD) is controversial.

HYPOTHESIS

Administration of spironolactone (2-4 mg q 24 h) and benazepril (0.25-0.5 mg q 24 h) in dogs with preclinical MMVD, not receiving any other cardiac medications, delays the onset of heart failure (HF) and cardiac-related death. Moreover, it reduces the progression of the disease as indicated by echocardiographic parameters and level of cardiac biomarkers N-terminal pro brain natriuretic peptide (NT-proBNP) and cardiac troponin I (cTnI).

ANIMALS

184 dogs with pre-clinical MMVD and left atrium-to-aortic root ratio (LA:Ao) ≥1.6 and normalized left ventricular end-diastolic diameter (LVEDDn) ≥1.7.

METHODS

This is a prospective, randomized, multicenter, single-blinded, placebo-controlled study. Primary outcome variable was time-to-onset of first occurrence of HF or cardiac death. Secondary end points included effect of treatment on progression of the disease based on echocardiographic and radiographic parameters, as well as variations of NT-proBNP and cTnI concentrations.

RESULTS

The median time to primary end point was 902 days (95% confidence interval (CI) 682-not available) for the treatment group and 1139 days (95% CI 732-NA) for the control group (p = 0.45). Vertebral heart score (p = 0.05), LA:Ao (p < 0.001), LVEDDn (p < 0.001), trans-mitral E peak velocity (p = 0.011), and NT-proBNP (p = 0.037) were lower at the end of study in the treatment group.

CONCLUSIONS

This study failed in demonstrating that combined administration of spironolactone and benazepril delays onset of HF in dogs with preclinical MMVD. However, such treatment induces beneficial effects on cardiac remodeling and these results could be of clinical relevance.

Correlation between NT-proBNP and lipase levels according to the severity of chronic mitral valve disease in dogs

Chronic mitral valve disease (CMVD) is the most common cardiovascular disease in dogs, causing decreased cardiac output that results in poor tissue perfusion and tissue damage to kidneys, pancreas, and other organs. The purpose of this study was to evaluate the relationships between heart disease severity and N-terminal pro B-type natriuretic peptide (NT-proBNP) and lipase in dogs with CMVD, as well as to evaluate longitudinal changes in these values. A total of 84 dogs participated in this 2015 to 2017 study. Serum values of NT-proBNP and lipase were analyzed; radiography was used to measure the vertebral heart score and assess various echocardiographic values. NT-proBNP showed a strong positive correlation with increasing stage of heart disease; lipase showed a mild positive correlation with heart disease stage. When the three values (NT-proBNP, lipase and month) were continuously measured at 6-month intervals, all showed a correlation with the increasing length of the disease.

Echocardiographic quantitation of left heart size and function in 122 healthy dogs: A prospective study proposing reference intervals and assessing repeatability

Background

Broadly applicable reference intervals (RIs) for measurements of left atrial (LA) and left ventricular (LV) size and function generated prospectively using statistically appropriate methods are limited.

Objectives

To generate body size‐independent RIs for linear, area, and volume measurements of LA size and LV size and function.

Animals

Healthy adult dogs (n = 122) of variable size and somatotype.

Methods

Prospective study. All dogs underwent an echocardiogram performed by the same examiner. Effects of body weight, sex, age, and heart rate were evaluated by regression and correlation analyses. Scaling exponents and prediction intervals were generated for linear measurements using the allometric equation. After normalization to body weight, 95% RIs were determined using nonparametric methods with 2.5 and 97.5 percentiles serving as the lower and upper limits (each with 90% confidence intervals), respectively.

Results

Linear LA and LV measurements were strongly correlated (R² ≥ 0.79) with body weight. Scaling exponents were close to the expected 1/3 (0.299‐0.392). Prediction intervals for linear measurements of LV chamber size were considerably narrower than previously reported. Weak correlations (r = −0.42 to −0.50) among LV fractional shortening, fractional area change, and ejection fraction and body weight were identified. No other meaningful relationships were identified between the measurements and sex, age, and heart rate.

Conclusions and Clinical Importance

Body size‐independent RIs for several linear, area, and volume measurements of LA and LV size and function were generated prospectively from a large and diverse reference population and are available for clinical use.

ACVIM consensus guidelines for the diagnosis and treatment of myxomatous mitral valve disease in dogs

This report, issued by the ACVIM Specialty of Cardiology consensus panel, revises guidelines for the diagnosis and treatment of myxomatous mitral valve disease (MMVD, also known as endocardiosis and degenerative or chronic valvular heart disease) in dogs, originally published in 2009. Updates were made to diagnostic, as well as medical, surgical, and dietary treatment recommendations. The strength of these recommendations was based on both the quantity and quality of available evidence supporting diagnostic and therapeutic decisions. Management of MMVD before the onset of clinical signs of heart failure has changed substantially compared with the 2009 guidelines, and new strategies to diagnose and treat advanced heart failure and pulmonary hypertension are reviewed.

Echocardiographic indices and severity of mitral regurgitation in dogs with preclinical degenerative mitral valve disease

Background

Describing severity of mitral regurgitation (MR) in dogs with degenerative mitral valve disease (DMVD) is challenging.

Hypothesis/Objectives

Mitral regurgitant fraction (RF), effective regurgitant orifice area (EROA), and the ratio of mitral regurgitant to aortic flow (Q_MR:Q_Ao) can be calculated from routine echocardiographic measurements and provide additional information regarding MR severity.

Animals

Fifty‐seven dogs with preclinical DMVD including 36 without and 21 with cardiomegaly.

Methods

Prospective observational study. The expected relationships among RF, EROA, and Q_MR:Q_Ao and 1‐dimensional measurements including left atrium to aortic root diameter ratio (LA:Ao) and normalized left ventricular internal dimension at end‐diastole (LVIDdN) were mathematically derived and calculated using echocardiographic data from the study population. Nonlinear goodness of fit was determined by calculation of the root mean standard error. The correlations between 1‐dimensional and multidimensional indices were analyzed using receiver operating characteristic curves.

Results

The relationships among RF, EROA, Q_MR:Q_Ao, and both LA:Ao and LVIDdN were curvilinear, and the multidimensional indices differentiated MR of variable severity. By contrast, 1‐dimensional measurements were insensitive to MR severity until RF equaled or exceeded 50%. Regurgitant fraction ≥50%, EROA to body surface area ≥0.347 and Q_MR:Q_Ao ≥0.79 were strongly associated with LA:Ao ≥1.6 and LVIDdN ≥1.7.

Conclusions and Clinical Importance

Regurgitant fraction, EROA, and Q_MR:Q_Ao quantify MR severity in dogs with preclinical DMVD in a manner that 1‐dimensional measurements do not.

Factors associated with disease progression in dogs with presumed preclinical degenerative mitral valve disease attending primary care veterinary practices in the United Kingdom

BACKGROUND

Factors associated with disease progression in dogs with preclinical (stage B) degenerative mitral valve disease (DMVD) have not been evaluated previously in primary care veterinary practice.

OBJECTIVES

To evaluate whether plasma cardiac biomarkers, clinical signs, and physical examination findings are associated with clinical progression (reaching the composite endpoint of initiation of treatment with a potent diuretic or cardiac death) in dogs presumed to have stage B DMVD.

ANIMALS

Six-hundred and eighty-four dogs diagnosed with DMVD recruited from 73 primary care practices in the United Kingdom. Dogs were not receiving potent diuretics at recruitment.

METHODS

Prospective cohort study design. Primary care veterinarians recorded the presence or absence of clinical signs and physical examination findings. Baseline plasma N-terminal pro B-type natriuretic peptide (NT-proBNP) and cardiac troponin I were measured. Cox regression models measured associations between risk factor variables and clinical progression. Flexible parametric models generated predicted probabilities of reaching the composite endpoint for dogs with different combinations of prognostic risk factor variables.

RESULTS

Plasma NT-proBNP, heart rate, heart murmur intensity, presence of a cough, being a Cavalier King Charles Spaniel, and being prescribed pimobendan were associated with clinical progression to initiation of treatment with a potent diuretic or cardiac-related death.

CONCLUSIONS AND CLINICAL IMPORTANCE

Dogs with stage B DMVD identified as having a high risk of disease progression might benefit from more frequent monitoring or further diagnostic evaluation. The prognostic factors identified could facilitate risk stratification of dogs presenting with preclinical DMVD.

Prognostic factors in dogs with presumed degenerative mitral valve disease attending primary-care veterinary practices in the United Kingdom

Background

Prognostic risk factors were identified for dogs with degenerative mitral valve disease (DMVD) monitored by veterinary cardiologists. The value of these measurements has not been determined in the wider primary care setting.

Objectives

To evaluate whether plasma cardiac biomarkers and data obtained from routine history‐taking and physical examination are predictive of survival in dogs with DMVD attending primary care practice.

Animals

Eight‐hundred and ninety‐three dogs with a presumptive diagnosis of DMVD recruited from 79 primary care veterinary practices in the United Kingdom.

Methods

Prospective cohort study. Primary care veterinary practitioners recorded clinical data. Plasma N‐terminal pro B‐type natriuretic peptide (NT‐proBNP) and cardiac troponin I (cTnI) were measured at presentation. Cox regression models evaluated associations between risk factor variables and hazard of death (all‐cause mortality and cardiac‐related death). Flexible parametric models generated predicted survival probabilities for dogs with different combinations of prognostic risk factor variable values.

Results

Dogs with higher NT‐proBNP and cTnI concentrations, higher heart rates, older dogs, females, and those reported to be exercise intolerant, dyspneic, and diagnosed with selected comorbidities had an increased hazard of death due to any cause. Dogs with higher concentrations of plasma biomarkers, higher heart rates, and heart murmur intensities, those with exercise intolerance and those receiving potent diuretics had a higher hazard of cardiac‐related death.

Conclusions and Clinical Importance

Cardiac biomarkers and key clinical findings identified in this study can help primary care veterinary practitioners identify dogs with DMVD that are at highest risk of death.

Echocardiographic Estimates of Right Ventricular Systolic Function in Dogs with Myxomatous Mitral Valve Disease

Background

Right ventricular (RV) dysfunction independently predicts outcomes in human myxomatous mitral valve disease (MMVD). There is limited information regarding RV systolic function in dogs with MMVD.

Hypothesis

Right ventricular systolic function differs among stages of disease, decreasing in decompensated MMVD.

Animals

Thirty‐sixclient‐owned dogs with MMVD not receiving oral cardiovascular medications.

Methods

Prospective clinical study. Dogs were categorized according to disease severity as ACVIM Stage B1, B2, or C. Seven echocardiographic indices of RV systolic function were measured. Groups were compared by 1‐way ANOVA and Tukey's HSD test. Frequencies of cases with cardiac remodeling falling outside previously established reference intervals were compared using Fisher's exact test. Intra‐ and interobserver measurement variability was calculated for each RV function index.

Results

The indices TAPSE (P = 0.029), RV St_L (P = 0.012), and RV StR_L (P = 0.041) were significantly different between groups. A greater proportion of B2 dogs (7 of 12) had TAPSE values above reference intervals compared with B1 (2 of 12) or C (2 of 12) dogs (P = 0.027). Measurement variability of TAPSE, RV S', and RV St_G was clinically acceptable.

Conclusions and Clinical Importance

Right ventricular systolic function differs between stages of MMVD, increasing in stage B2, and declining in stage C. The prognostic importance of RV function indices, particularly TAPSE, might be worth evaluating in dogs with MMVD.

Longitudinal Analysis of Quality of Life, Clinical, Radiographic, Echocardiographic, and Laboratory Variables in Dogs with Preclinical Myxomatous Mitral Valve Disease Receiving Pimobendan or Placebo: The EPIC Study

Background

Changes in clinical variables associated with the administration of pimobendan to dogs with preclinical myxomatous mitral valve disease (MMVD) and cardiomegaly have not been described.

Objectives

To investigate the effect of pimobendan on clinical variables and the relationship between a change in heart size and the time to congestive heart failure (CHF) or cardiac‐related death (CRD) in dogs with MMVD and cardiomegaly. To determine whether pimobendan‐treated dogs differ from dogs receiving placebo at onset of CHF.

Animals

Three hundred and fifty‐four dogs with MMVD and cardiomegaly.

Materials and Methods

Prospective, blinded study with dogs randomized (ratio 1:1) to pimobendan (0.4–0.6 mg/kg/d) or placebo. Clinical, laboratory, and heart‐size variables in both groups were measured and compared at different time points (day 35 and onset of CHF) and over the study duration. Relationships between short‐term changes in echocardiographic variables and time to CHF or CRD were explored.

Results

At day 35, heart size had reduced in the pimobendan group: median change in (Δ) LVIDDN −0.06 (IQR: −0.15 to +0.02), P < 0.0001, and LA:Ao −0.08 (IQR: −0.23 to +0.03), P < 0.0001. Reduction in heart size was associated with increased time to CHF or CRD. Hazard ratio for a 0.1 increase in ΔLVIDDN was 1.26, P = 0.0003. Hazard ratio for a 0.1 increase in ΔLA:Ao was 1.14, P = 0.0002. At onset of CHF, groups were similar.

Conclusions and Clinical Importance

Pimobendan treatment reduces heart size. Reduced heart size is associated with improved outcome. At the onset of CHF, dogs treated with pimobendan were indistinguishable from those receiving placebo.

Vasovagal tonus index in dog with myxomatous mitral valve disease

ABSTRACT: The vasovagal tonus index (VVTI) is a useful and assessable index, obtained from standard ECG recordings, that is used to estimate heart rate variability (HRV), and may provide valuable information regarding the likelihood of progression into congestive heart failure (CHF). In this paperwork, we investigated how the vasovagal tonus index (VVTI) behaves in dogs with naturally-occurring myxomatous mitral valve disease (MMVD) Electrocardiographic (ECG) recordings and echocardiographic data of 120 patients diagnosed with MMVD were reviewed. The VVTI was calculated from twenty consecutive RR intervals for each dog enrolled in the study. Lower VVTI values were found in MMVD patients in American College of Veterinary Internal Medicine (ACVIM) stage C compared with stages B1 and B2. Values were also lower in patients with severe cardiac remodeling. When a cut-off value of 6.66 is used, VVTI was able to discriminate MMVD patients in stage C from B1 and B2 dogs with a sensitivity of 70 per cent and a specificity of 77 per cent. MMVD dogs in which VVTI is lower than 6.66 are 30% more likely to develop congestive heart failure (CHF).

Review of Diagnostic and Therapeutic Approach to Canine Myxomatous Mitral Valve Disease

The most common heart disease that affects dogs is myxomatous mitral valve disease. In this article, we review the current diagnostic and therapeutic approaches to this disease, and we also present some of the latest technological advancements in this field.

Mitral Regurgitation Severity and Left Ventricular Systolic Dimension Predict Survival in Young Cavalier King Charles Spaniels

Background

Development and progression of myxomatous mitral valve disease (MMVD) in dogs are difficult to predict. Identification at a young age of dogs at high risk of adverse outcome in the future is desirable.

Hypothesis/Objectives

To study the predictive value of selected clinical and echocardiographic characteristics associated with MMVD obtained at a young age for prediction of long‐term cardiac and all‐cause mortality in Cavalier King Charles Spaniels (CKCS).

Animals

1125 privately owned CKCS.

Methods

A retrospective study including CKCS examined at the age of 1–3 years. Long‐term outcome was assessed by telephone interview with owners. The value of variables for predicting mortality was investigated by Cox proportional hazard and Kaplan‐Meier analyses.

Results

Presence of moderate to severe mitral regurgitation (MR) (hazard ratio (HR) = 3.03, 95% confidence interval (95% CI) = 1.48–6.23, P = 0.0025) even intermittent moderate to severe MR (HR = 2.23, 95% CI = 1.48–6.23, P = 0.039) on color flow Doppler echocardiography was significantly associated with increased hazard of cardiac death. An interaction between MR and sex was significant for all‐cause mortality (P = 0.035), showing that males with moderate to severe MR had a higher all‐cause mortality compared to males with no MR (HR = 2.38, 95% CI = 1.27–4.49, P = 0.0071), whereas no difference was found between female MR groups. The risk of cardiac (HR = 1.37, 95% CI = 1.14–1.63, P < 0.001) and all‐cause (HR = 1.13, 95% CI = 1.02–1.24, P = 0.016) mortality increased with increasing left ventricular end‐systolic internal dimension normalized for body weight (LVIDS_N).

Conclusions and clinical importance

Moderate to severe MR, even if intermittent, and increased LVIDS_N in dogs <3 years of age were associated with cardiac death later in life in CKCS.

Plasma coenzyme Q10 concentration, antioxidant status, and serum N-terminal pro-brain natriuretic peptide concentration in dogs with various cardiovascular diseases and the effect of cardiac treatment on measured variables

OBJECTIVE To determine the plasma total antioxidant capacity, erythrocyte superoxide dismutase activity, whole blood glutathione peroxidase activity, and plasma coenzyme Q₁₀ (CoQ₁₀) concentration in dogs with various stages of cardiovascular diseases and in healthy dogs; assess the influence of cardiac treatment on the levels of antioxidant variables, plasma CoQ₁₀ concentration, and serum N-terminal pro-brain natriuretic peptide (NT-proBNP) concentration, and determine any correlation between the disease severity (NT-proBNP concentration) and antioxidant variables or CoQ₁₀ concentration. ANIMALS 43 dogs with various types and stages of cardiovascular diseases (congenital and acquired) and 29 healthy dogs. PROCEDURES Blood samples were collected from all dogs for spectrophotometric assessment of antioxidant variables. Plasma CoQ₁₀ concentration was determined with a high-performance liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry method. Serum NT-proBNP concentration was measured with an ELISA. RESULTS Values for antioxidant variables did not differ among groups of dogs with cardiovascular diseases, regardless of disease stage or treatment. Plasma CoQ₁₀ concentration was significantly increased in treated dogs with congestive heart failure (CHF), compared with untreated patients. However, plasma CoQ₁₀ concentration did not differ among heart failure classes. A significant, negative correlation between serum NT-proBNP and plasma CoQ₁₀ concentrations was identified in treated CHF-affected dogs, suggesting that low plasma CoQ₁₀ concentration may be associated with increased severity of CHF. CONCLUSIONS AND CLINICAL RELEVANCE The antioxidant variables evaluated were not altered in dogs with CHF, regardless of cardiac disease stage or treatment. Further investigation into the possible effects of CoQ₁₀ supplementation in dogs with advanced stages of CHF is warranted.

Association between Survival Time and Changes in NT-proBNP in Cats Treated for Congestive Heart Failure

Background

Reductions in N‐terminal pro‐B‐type natriuretic peptide (NT‐proBNP) concentrations after treatment have been associated with improved survival in people with congestive heart failure (CHF), but have not been reported in cats with CHF.

Objectives

To evaluate changes in NT‐proBNP concentrations in cats with CHF after treatment and determine whether serial NT‐proBNP measurements provide prognostic information.

Animals

Thirty‐one client‐owned cats.

Methods

Prospective, observational study in cats with new onset CHF secondary to cardiomyopathy. Concentrations of NT‐proBNP were measured within 4 hours of admission to the hospital, on the day of discharge, and at re‐evaluation 7–10 days later.

Results

Median NT‐proBNP concentrations decreased significantly from admission (1,713 pmol/L [range, 160–3,784 pmol/L]) to discharge (902 pmol/L [range, 147–3,223 pmol/L]); P = .005) and from admission to re‐evaluation (1,124 pmol/L [range, 111–2,727 pmol/L]; P = .024). Median survival time was 109 days (range, 1–709 days), with 5 cats still alive at the time of analysis. Cats with a larger percent decrease in NT‐proBNP from admission to discharge had a longer survival time (P = .048). Cats with evidence of active CHF at the time of re‐evaluation (P = .010) and cats whose owners had difficulty administering medications (P = .045) had shorter survival times.

Conclusions and clinical importance

Cats with a larger percent decrease in NT‐proBNP during hospitalization and no evidence of CHF at the time of re‐evaluation had longer survival times. Additional studies are needed to determine whether NT‐proBNP can help guide treatment in cats with CHF.

Quality of Life Score as a Predictor of Death in Dogs with Degenerative Mitral Valve Disease

Background

The knowledge of the variables predicting mortality is important in clinical practice and for therapeutic monitoring in mitral valve disease.

Objectives

To determine whether a quality of life score evaluated with the Functional Evaluation of Cardiac Health questionnaire would predict mortality in dogs with degenerative mitral valve disease (DMVD).

Methods

Thirty-six client-owned dogs with mitral valve disease underwent clinical, laboratory, and echocardiographic evaluations at baseline and were monitored for 6 months. Cardiovascular death was the primary outcome.

Results

The 36 dogs were classified as survivors or nonsurvivors. Higher values of the following variables were obtained at baseline in the nonsurviving group (12 dogs): amino-terminal pro-B-type natriuretic peptide (NT-proBNP) levels, plasma norepinephrine, heart rate, quality of life score, diastolic left ventricular internal dimension to aortic root ratio, systolic left ventricular internal dimension to aortic root ratio, and left atrium to aortic root ratio. NT-proBNP levels and quality life score were independently associated with death in the multivariable analysis.

Conclusion

The quality life score was an independent variable for cardiac death in dogs with DMVD. This result is encouraging, as this score is easy to apply and does not require any technology, only a veterinarian and an observant owner.

Breed-Specific Vertebral Heart Scale for the Dachshund

The objectives of this study were to determine a breed-specific vertebral heart scale (VHS) range for the dachshund and compare results to the established reference range of 9.7 ± 0.5, calculate inter-observer variability, and correlate VHS with echocardiography. Fifty-one normal dachshunds had radiographs and an echocardiogram performed. Five observers measured VHS to the nearest 0.25 vertebra. The data was analyzed using one-way analysis of variance, Wilcoxon Rank Sum test, Mann-Whitney rank sum test, calculation of reference and confidence intervals, Spearman rank-order correlations, and generation of intra-class correlations and confidence intervals. P &lt; .05 was considered significant. The median for right lateral VHS was significantly larger than left (10.3 [range 9.25–11.55] versus 10.1 [range, 8.7–11.31], p &lt; .0001). VHS for females was significantly larger than for males (left: 10.56 [9.2–11.31] versus 9.74 [8.7–10.88] and right: 10.8 [9.5–11.55] versus 9.99 [9.25–10.8], p = .0002). Observer consistency was high with an intra-class correlation coefficient of 0.95. No significant correlation was found between left atrial echocardiographic parameters and VHS. Results indicate normal dachshunds have a median VHS above the published generic canine reference range, and VHS can be reliably performed by observers with varying degrees of clinical experience.

Biologic variability of N-terminal pro-brain natriuretic peptide in healthy dogs and dogs with myxomatous mitral valve disease

INTRODUCTION

To determine the biologic variability of N-terminal pro-brain natriuretic peptide (NTproBNP) in healthy dogs and dogs with various stages of myxomatous mitral valve disease (MMVD).

ANIMALS

Thirty-eight privately owned dogs: 28 with MMVD and 10 healthy controls.

MATERIALS AND METHODS

Prospective clinical study with comprehensive evaluation used to group dogs as healthy or into three stages of MMVD based on current guidelines. NTproBNP was measured hourly, daily, and weekly. For each group, analytical (CV_A), within-subject (CV_I), and between-subject (CV_G) coefficients of variability were calculated in addition to percent critical change value (CCV) and index of individuality (IoI).

RESULTS

For healthy dogs, calculated NTproBNP values were: CV_A = 4.2%; CV_I = 25.2%; CV_G = 49.3%; IoI = 0.52, and CCV = 70.8%. For dogs with MMVD, calculated NTproBNP values were: CV_A = 6.2%; CV_I = 20.0%; CV_G = 61.3%; IoI = 0.34, and CCV = 58.2%.

CONCLUSIONS

Biologic variability affects NTproBNP concentrations in healthy dogs and dogs with MMVD. Monitoring serial individual changes in NTproBNP may be clinically relevant in addition to using population-based reference ranges to determine changes in disease status.

Effect of Pimobendan in Dogs with Preclinical Myxomatous Mitral Valve Disease and Cardiomegaly: The EPIC Study-A Randomized Clinical Trial

Background

Pimobendan is effective in treatment of dogs with congestive heart failure (CHF) secondary to myxomatous mitral valve disease (MMVD). Its effect on dogs before the onset of CHF is unknown.

Hypothesis/Objectives

Administration of pimobendan (0.4–0.6 mg/kg/d in divided doses) to dogs with increased heart size secondary to preclinical MMVD, not receiving other cardiovascular medications, will delay the onset of signs of CHF, cardiac‐related death, or euthanasia.

Animals

360 client‐owned dogs with MMVD with left atrial‐to‐aortic ratio ≥1.6, normalized left ventricular internal diameter in diastole ≥1.7, and vertebral heart sum >10.5.

Methods

Prospective, randomized, placebo‐controlled, blinded, multicenter clinical trial. Primary outcome variable was time to a composite of the onset of CHF, cardiac‐related death, or euthanasia.

Results

Median time to primary endpoint was 1228 days (95% CI: 856–NA) in the pimobendan group and 766 days (95% CI: 667–875) in the placebo group (P = .0038). Hazard ratio for the pimobendan group was 0.64 (95% CI: 0.47–0.87) compared with the placebo group. The benefit persisted after adjustment for other variables. Adverse events were not different between treatment groups. Dogs in the pimobendan group lived longer (median survival time was 1059 days (95% CI: 952–NA) in the pimobendan group and 902 days (95% CI: 747–1061) in the placebo group) (P = .012).

Conclusions and Clinical Importance

Administration of pimobendan to dogs with MMVD and echocardiographic and radiographic evidence of cardiomegaly results in prolongation of preclinical period and is safe and well tolerated. Prolongation of preclinical period by approximately 15 months represents substantial clinical benefit.

Clinical severity score system in dogs with degenerative mitral valve disease

BACKGROUND

Several risk factors already have been determined for dogs with degenerative mitral valve disease (DMVD). Risk factors often have been considered in isolation and have not always taken into account additional information provided by the history and physical examination (PE).

HYPOTHESIS/OBJECTIVES

Data obtained from history and PE of dogs with DMVD provide prognostic information and can be used for risk stratification.

ANIMALS

Client-owned dogs (n = 244) with DMVD recruited from first opinion practice.

METHODS

Prospective longitudinal follow-up of dogs with DMVD. History and PE data were obtained at 6-month intervals and analyzed with time-dependent Cox models to derive relative risk of cardiac death. Independent hazard ratios were used to derive a clinical severity score (CSS), the prognostic value of which was evaluated by analyzing the median survival times for different risk groups and ROC analysis. Analysis of the progression of CSS over time also was undertaken.

RESULTS

History of cough, exercise intolerance, decreased appetite, breathlessness (difficulty breathing) and syncope with PE findings of heart murmur intensity louder than III/VI and absence of respiratory sinus arrhythmia were independently associated with outcome and allowed development of the CSS. Clinical severity score distinguished groups of dogs with significantly different outcomes.

CONCLUSIONS AND CLINICAL IMPORTANCE

Routinely obtained clinical findings allow risk stratification of dogs with DMVD. Results of ancillary diagnostic tests may be complementary to history and PE findings and always should be interpreted in conjunction with these findings.

Pulmonary Vein-to-Pulmonary Artery Ratio is an Echocardiographic Index of Congestive Heart Failure in Dogs with Degenerative Mitral Valve Disease

BACKGROUND

Early recognition of left-sided congestive heart failure (CHF) in dogs with degenerative mitral valve disease (DMVD) is important because it influences medical therapy, timing of follow-up, and outcome.

HYPOTHESIS

Pulmonary vein diameter-to-pulmonary artery diameter ratio (PV/PA) measured by echocardiography can predict CHF.

ANIMALS

Ninety-eight client-owned dogs, 37 controls, and 61 dogs with DMVD.

METHODS

Prospective clinical cohort study. History, physical examination and Doppler-echocardiography were performed. Dogs were classified as International Small Animal Cardiac Health Council class I, II or III. Congestive heart failure was identified in a subset of 56 dogs based on radiographic findings. The PV/PA was measured in bidimensional (2D) and M-mode by 2 investigators blinded to the radiologists' conclusions.

RESULTS

Interobserver coefficients of variation for PV/PA acquisition and measurement were <10%. The PV/PA in control dogs was approximately 1 and increased with class of heart failure. The presence of CHF could be best predicted by measuring PV/PA in 2D echocardiography (cut-off, 1.7; area under the curve, 0.98; CI, 0.97-0.98; P < .001) with a sensitivity of 96% and a specificity of 91%.

CONCLUSION AND CLINICAL IMPORTANCE

The PV/PA is a simple and reproducible echocardiographic variable that increases with class of heart failure and may help discriminate dogs in CHF from asymptomatic dogs with DMVD. Additional studies are required to determine whether PV/PA might provide additional information in the integrated interpretation of Doppler-echocardiographic indices of left ventricular filling pressures and could be used for rapid assessment of CHF in dogs in a critical care setting.

Analytical validation of a second-generation immunoassay for the quantification of N-terminal pro-B-type natriuretic peptide in canine blood

N-terminal pro-B-type natriuretic peptide (NT-proBNP) has been shown to have clinical utility as a biomarker in dogs with heart disease. There were several limitations associated with early diagnostic assay formats including a limited dynamic range and the need for protease inhibitors to maintain sample stability. A second-generation Cardiopet® proBNP enzyme-linked immunosorbent assay (IDEXX Laboratories Inc., Westbrook, Maine) was developed to address these limitations, and the present study reports the results of the analytical method validation for the second-generation assay. Coefficients of variation for intra-assay, interassay, and total precision based on 8 samples ranged from 3.9% to 8.9%, 2.0% to 5.0%, and 5.5% to 10.6%, respectively. Analytical sensitivity was established at 102 pmol/l. Accuracy averaged 102.0% based on the serial dilutions of 5 high-dose canine samples. Bilirubin, lipids, and hemoglobin had no effect on results. Reproducibility across 3 unique assay lots was excellent with an average coefficient of determination (r (2)) of 0.99 and slope of 1.03. Both ethylenediamine tetra-acetic acid plasma and serum gave equivalent results at time of blood draw (slope = 1.02, r (2) = 0.89; n = 51) but NT-proBNP was more stable in plasma at 25°C with median half-life measured at 244 hr and 136 hr for plasma and serum, respectively. Plasma is the preferred sample type and is considered stable up to 48 hr at room temperature whereas serum should be frozen or refrigerated when submitted for testing. Results of this study validate the second-generation canine Cardiopet proBNP assay for accurate and precise measurement of NT-proBNP in routine sample types from canine patients.

Cardiovascular-renal axis disorders in the domestic dog and cat: a veterinary consensus statement

OBJECTIVES

There is a growing understanding of the complexity of interplay between renal and cardiovascular systems in both health and disease. The medical profession has adopted the term "cardiorenal syndrome" (CRS) to describe the pathophysiological relationship between the kidney and heart in disease. CRS has yet to be formally defined and described by the veterinary profession and its existence and importance in dogs and cats warrant investigation. The CRS Consensus Group, comprising nine veterinary cardiologists and seven nephrologists from Europe and North America, sought to achieve consensus around the definition, pathophysiology, diagnosis and management of dogs and cats with "cardiovascular-renal disorders" (CvRD). To this end, the Delphi formal methodology for defining/building consensus and defining guidelines was utilised.

METHODS

Following a literature review, 13 candidate statements regarding CvRD in dogs and cats were tested for consensus, using a modified Delphi method. As a new area of interest, well-designed studies, specific to CRS/CvRD, are lacking, particularly in dogs and cats. Hence, while scientific justification of all the recommendations was sought and used when available, recommendations were largely reliant on theory, expert opinion, small clinical studies and extrapolation from data derived from other species.

RESULTS

Of the 13 statements, 11 achieved consensus and 2 did not. The modified Delphi approach worked well to achieve consensus in an objective manner and to develop initial guidelines for CvRD.

DISCUSSION

The resultant manuscript describes consensus statements for the definition, classification, diagnosis and management strategies for veterinary patients with CvRD, with an emphasis on the pathological interplay between the two organ systems. By formulating consensus statements regarding CvRD in veterinary medicine, the authors hope to stimulate interest in and advancement of the understanding and management of CvRD in dogs and cats. The use of a formalised method for consensus and guideline development should be considered for other topics in veterinary medicine.

Expression Profiling of Circulating MicroRNAs in Canine Myxomatous Mitral Valve Disease

MicroRNAs (miRNAs) are small non-coding RNAs that have shown promise as noninvasive biomarkers in cardiac disease. This study was undertaken to investigate the miRNA expression profile in dogs with myxomatous mitral valve disease (MMVD). 277 miRNAs were quantified using RT-qPCR from six normal dogs (American College of Veterinary Internal Medicine Stage A), six dogs with MMVD mild to moderate cardiac enlargement (ACVIM Stage B1/B2) and six dogs with MMVD and congestive heart failure (ACVIM Stage C/D). Eleven miRNAs were differentially expressed (False Discovery Rate < 0.05). Dogs in Stage B1/B2 or C/D had four upregulated miRNAs, including three cfa-let-7/cfa-miR-98 family members, while seven others were downregulated, compared to Stage A. Expression of six of the 11 miRNAs also were significantly different between dogs in Stage C/D and those in Stage B1/B2. The expression changes were greater as disease severity increased. These miRNAs may be candidates for novel biomarkers and may provide insights into genetic regulatory pathways in canine MMVD.