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Abstract Background Information regarding the frequency of L waves and their prognostic relevance in dogs with secondary atrial fibrillation (AF) is limited. Hypothesis/Objectives To determine whether L waves occur and ascertain their prognostic role, as well as the role of other clinical and echocardiographic variables in dogs with AF. Animals Fifty-five dogs with AF associated with myxomatous mitral valve disease or dilated cardiomyopathy. Methods Retrospective, multicenter observational study. In addition to L waves analysis, other clinical and echocardiographic variables, including type of antiarrhythmic treatment, were evaluated. A survival analysis was performed to test for predictors of cardiac death and all-cause mortality using Cox proportional hazards regression models. Results L waves were evident in 33/55 dogs (60%, 95% confidence interval [CI] = 47%-72%) but their presence did not influence outcome. Increased left ventricular end-systolic diameter normalized for body weight (LVSDn) was a significant predictor of both cardiac death (hazard ratio [HR] = 4.41, 95% CI = 1.18-16.54; P = .03) and all-cause mortality (HR = 9.39, 95% CI = 2.49-35.32; P < .001). Heart rate assessed during echocardiography (Echo-HR) represented an additional significant predictor of cardiac death (HR = 1.01, 95% CI = 1.00-1.01; P = .04) and all-cause mortality (HR = 1.01, 95% CI = 1.00-1.01; P = .04). Conclusions and Clinical Importance L waves occurred frequently in dogs with AF, but held no prognostic relevance. Conversely, LVSDn and Echo-HR represented independent predictors of negative outcome in these animals.

Symmetric dimethylarginine (SDMA) is a serum biomarker of renal damage in dogs. Moreover, SDMA concentration is an independent predictor of development of severe heart failure (HF) in humans with cardiac disease. This study evaluates whether the serum concentration of SDMA in dogs with myxomatous mitral valve disease (MMVD) is influenced by the severity of heart disease, pulmonary hypertension (PH) and treatment of HF. A total of 99 client-owned dogs were included in this retrospective case-control study; 78 dogs were affected by MMVD and classified according to the American College of Veterinary Internal Medicine (ACVIM) guidelines, and 21 were healthy controls. For each dog, history, physical examination, complete blood count, biochemical profile, thoracic radiography, 6-lead standard electrocardiogram and trans-thoracic echocardiography were available. Comparisons were performed between groups of dogs belonging to different ACVIM stages and between dogs with and without PH. The median SDMA concentration was neither significantly different among groups of dogs in different disease stages (overall P = 0.010), nor among dogs with MMVD, nor between those with [14.5 [mu]g/dl (10.5-18.8)] and without PH [13 [mu]g/dl (9-17.2)] (P = 0.295). The concentration of SDMA did not differ between dogs when considering the combined effect of the ACVIM group and cardiac treatment (overall P = 0.486). Furthermore, no correlation was found between SDMA concentration and radiographic and echocardiographic parameters associated with increased MMVD severity. In conclusion, this study failed to demonstrate the presence of renal impairment in dogs with MMVD, and the increase in renal parameters in some dogs in the more advanced stage of MMVD could be attributed to pre-renal azotemia.

[This corrects the article DOI: 10.1371/journal.pone.0227807.].

The Lorenz plot (LP), a graphical representation of heart rate variability, has been poorly studied in dogs to date. The present study aimed to describe the graphic features of LP in dogs with sinus rhythm (SR) and tachyarrhythmias, and to analyze the usefulness of its pattern recognition. One hundred and nineteen canine Holter recordings were retrospectively evaluated. Cardiac rhythms were classified as: SR; SR with frequent (>100) premature ectopies (atrial, SR-APCs; ventricular, SR-VPCs; atrial and ventricular, SR-APCs-VPCs); atrial fibrillation (AF); and AF with frequent VPCs (AF-VPCs). Lorenz plots were studied qualitatively and quantitatively, and classified by distinct LP patterns (LPPs). Repeatability and reproducibility of LPP classification and diagnostic value were determined. Recordings included: 48 SR, 9 SR-APCs, 35 SR-VPCs, 5 SR-APCs-VPCs, 4 AF, and 18 AF-VPCs. Ten LPPs were identified: comet (n = 12), torpedo (n = 3), Y-shaped (n = 6), diamond (n = 10), diamond with a central silent zone (n = 17), double side-lobe (DSL) (n = 47), triple side-lobe (n = 1), quadruple side-lobe (n = 2), fan (n = 18), and fan with DSL (n = 3). Repeatability and reproducibility of LPP classification were excellent. The DSL pattern was both highly sensitive (91.3%) and specific (94.5%) for SR with frequent premature ectopies, either APCs, or VPCs, or both. The remaining LPPs had lower diagnostic value (high specificity but low sensitivity). Distinct rhythms imprint distinct and reproducible LPPs in dogs. The majority of canine LPPs are specific but insensitive indicators of SR and tachyarrhythmias.

The effect of seasonal variation on hospital admissions and outcomes in humans with cardiovascular disease and congestive heart failure (CHF) has been described. This study evaluates the effect of temperature variation on admissions and outcomes in dogs with myxomatous mitral valve disease (MMVD) and first onset CHF. Ninety-three client-owned dogs with MMVD and a first occurrence of pulmonary edema were included in this retrospective clinical cohort study. Recorded clinical and echocardiographic variables were accumulated and analyzed with dogs allocated into groups in a temperature-wise manner that considered the mean of the average (Tave) and maximum ambient temperature (Tmax) of the 14 days preceding hospital admission. A survival analysis was also performed. No difference was found in the percentage of dogs decompensating in three different temperature periods (i.e., cold, intermediate, and hot temperature) according to both Tave and Tmax. Dogs developing CHF during the intermediate temperatures according to Tmax died earlier from cardiac-related causes (median survival time 280 days, 95% CI = 147-486 days) compared to those decompensating during hot temperatures (median survival time 518 days, 95% CI = 344-819 days, P = 0.039). However, an effect of the ambient temperature on survival was not confirmed by Cox proportional hazard analysis. In conclusion, this study failed to show that ambient temperature has an effect on the first occurrence of CHF and outcomes in dogs with MMVD.

Abstract Background Atrial fibrillation (AF) occurs in dogs with myxomatous mitral valve disease (MMVD) as a consequence of left atrial (LA) dilatation, and it affects survival and quality of life. Objectives To evaluate the usefulness of echocardiography in predicting the first occurrence of AF in dogs with MMVD. Animals Forty-four client-owned dogs with MMVD, 22 dogs that developed AF, and 22 dogs that maintained sinus rhythm. Methods Retrospective observational study. Medical databases were reviewed for dogs that developed AF during the year after diagnosis of MMVD (AF group). The last echocardiographic examination obtained while still in sinus rhythm was used to derive selected variables. For each dog with AF, a control dog matched for body weight, class of heart failure, and LA dimension was selected. Echocardiographic results including LA volumes and LA speckle tracking echocardiography (STE)-derived variables were measured. Results Among the tested echocardiographic variables, only LA diameter (P = .03) and left ventricular internal diameter in diastole (P = .03) differed significantly between groups, whereas body weight-indexed variables of cardiac dimension as well as LA volumes and volume-derived functional variables were not different. Among the STE-derived variables, peak atrial longitudinal strain (PALS) results differed significantly between the AF group (23.8% ± 8.6%) and the control group (30.5% ± 9.6%; P = .03). A value of PALS ≤28% predicted AF occurrence with sensitivity and specificity of 0.80 and 0.65, respectively. Conclusions and Clinical Importance Absolute cardiac diameters and LA STE (in particular, PALS) are useful echocardiographic predictors for the development of AF in dogs with MMVD.

A heart-convolutional neural network (heart-CNN) was developed and tested for the automatic detection of left atrial enlargement (LAE) from feline thoracic radiographs. A retrospective and multicenter study was performed. Right lateral and dorso-ventral and/or ventro-dorsal thoracic radiographs of cats with concomitant echocardiographic examination were selected from the internal databases of both academic and private referral institutions. Radiographic images were classified as no LAE, mild, moderate and severe LAE, based on echocardiographic reports. Heart-CNN performance was evaluated using confusion matrices and receiver operating characteristic curves for both radiographic projections considering a multiclass and a binary classification. Considering the multiclass classification, for the right lateral view, the area under the curve (AUC) was of 0.73, 0.68, 0.64 and 0.78 for the no LAE, mild, moderate and severe LAE groups, respectively. The AUCs for the dorso-ventral and/or ventro-dorsal images were 0.73, 0.64, 0.63 and 0.76 for the no LAE, mild, moderate and severe LAE groups, respectively. In the binary classification, AUCs were 0.83 and 0.81 for right lateral and dorso-ventral and/or ventro-dorsal projections, respectively. The developed AI-based tool seems to be a promising support for automatic identification of more advanced stages of LAE in cats.

Atrial fibrillation (AF) and ventricular arrhythmias (VAs) are common pathological arrhythmias of dogs and are both associated with a poor prognosis in those with cardiac disease. This study aimed to assess the ability of 2 to 5 min electrocardiography (routine ECG) to detect the presence and severity of concomitant VAs in dogs with secondary AF. Continuous 24 h ECG monitoring (Holter) was used as the reference standard to identify VAs, quantify the number of premature ventricular ectopic complexes (VPCs) and evaluate the degree of their organization using a modified Lown–Wolf classification scale. In light of the Holter findings, VAs were classified as severe based on two criteria: the presence of more than 100 VPCs and a Lown–Wolf grade ≥ 4. Thirty-five dogs with secondary AF were included, where all exhibited VAs on Holter monitoring. Most dogs had severe VAs, according to both the VPC count (69%) and Lown–Wolf classification (77%). However, only 13 dogs (37%) had VAs detectable on routine ECG. A significant positive correlation was found between the presence of VAs on routine ECG and the severity of VAs identified via Holter. Nevertheless, the diagnostic accuracy of routine ECG in predicting severe VAs was only moderate (68.6% based on VPC count and 60% based on Lown–Wolf grade). Overall, a 2 to 5 min ECG appears to be a highly specific but relatively insensitive tool for detecting VAs in dogs with secondary AF.

Tissue-engineered heart valves are proposed as novel viable replacements granting longer durability and growth potential. However, they require extensive in vitro cell-conditioning in bioreactor before implantation. Here, the propensity of non-preconditioned decellularized heart valves to spontaneous in body self-regeneration was investigated in a large animal model. Decellularized porcine aortic valves were evaluated for right ventricular outflow tract (RVOT) reconstruction in Vietnamese Pigs (n = 11) with 6 (n = 5) and 15 (n = 6) follow-up months. Repositioned native valves (n = 2 for each time) were considered as control. Tissue and cell components from explanted valves were investigated by histology, immunohistochemistry, electron microscopy, and gene expression. Most substitutes constantly demonstrated in vivo adequate hemodynamic performances and ex vivo progressive repopulation during the 15 implantation months without signs of calcifications, fibrosis and/or thrombosis, as revealed by histological, immunohistochemical, ultrastructural, metabolic and transcriptomic profiles. Colonizing cells displayed native-like phenotypes and actively synthesized novel extracellular matrix elements, as collagen and elastin fibers. New mature blood vessels, i.e. capillaries and vasa vasorum, were identified in repopulated valves especially in the medial and adventitial tunicae of regenerated arterial walls. Such findings correlated to the up-regulated vascular gene transcription. Neoinnervation hallmarks were appreciated at histological and ultrastructural levels. Macrophage populations with reparative M2 phenotype were highly represented in repopulated valves. Indeed, no aspects of adverse/immune reaction were revealed in immunohistochemical and transcriptomic patterns. Among differentiated elements, several cells were identified expressing typical stem cell markers of embryonic, hematopoietic, neural and mesenchymal lineages in significantly higher number and specific topographic distribution in respect to control valves. Following the longest follow-up ever realized in preclinical models, non-preconditioned decellularized allogeneic valves offer suitable microenvironment for in vivo cell homing and tissue remodeling. Manufactured with simple, timesaving and cost-effective procedures, these promising valve replacements hold promise to become an effective alternative, especially for pediatric patients.

A five-month-old European shorthair female kitten was referred because of recurrent episodes of respiratory distress. Results of physical examination, thoracic radiography, and echocardiography led to a presumptive diagnosis of severe precapillary pulmonary hypertension (PH) and interstitial pneumonia associated with right-sided cardiac remodeling. The cat rapidly died because of respiratory insufficiency. Pulmonary and cardiovascular pathological findings evidenced left pulmonary artery coarctation, severe right-sided cardiac hypertrophy, and bilateral pneumonia. This is the first report of pulmonary artery coarctation associated with pneumonia and PH in a cat.