Os cães da raça Dachshund apresentam acondroplasia/hipocondroplasia, considerada uma condição fisiológica da raça, resultando num corpo longo com os membros curtos, arqueados e musculosos, esterno largo e proeminente, caixa torácica oval e ampla. Essas condições podem dificultar a realização e interpretação de alguns exames. A hipótese desse trabalho é que os cães da raça Dachshund tenham valores ecocardiográficos, eletrocardiográficos, radiográficos e pressóricos diferenciados. Para isso, foram estudados 69 cães adultos e sadios da raça Dachshund, sendo 28 (40,6%) machos e 41 (59,4%) fêmeas; com idade variando de 18 meses a 10 anos de idade; e peso médio de 8,4±2,3 kg. Foram realizados exames ecocardiográfico, eletrocardiográfico, radiográfico, bem como determinação de pressão arterial sistêmica em todos os animais. Para a análise dos resultados, os animais foram categorizados, segundo, gênero, presença ou ausência de castração, faixa etária (A: >1 a ≤ 3 anos, B: >3 a ≤ 6 anos e C: >6 a ≤ 10 anos), peso (< 8 kg e ≥ 8 kg) e circunferência torácica (> 45 cm e ≥ 45 cm). Foram estabelecidos, em cães adultos e sadios da raça Dachshund, os valores de ecocardiografia convencional, eletrocardiografia, radiografia e de pressão arterial sistêmica por meio do método Doppler Os resultados ecocardiográficos principais, com a média e intervalo de confiança de 95% foram: septo interventricular em diástole SIVd (6,5 [6,3-6,7] cm), parede livre de ventrículo esquerdo em diástole PLVEd (6,3 [6,1-6,4] cm), diâmetro interno de ventrículo esquerdo na diástole DIVEd (2,5 [2,5-2,6] cm), diâmetro interno de ventrículo esquerdo na sístole DIVEs (1,2 [1,2-1,3] cm), fração de encurtamento - FE -(51,32 [49,79-52,84]%), fração de ejeção do ventrículo esquerdo Fej (0,84 [0,82-0,85]). Não houve diferença estatística para gênero ou castração. Mas quando os cães foram separados pela faixa etária, houve diferença estatística significativa entre os grupos A e B (p = 0,0073) para SIVd e PLVEd; sendo que os valores para o grupo A foram de: SIVd (6,2 [5,9-6,5] cm) e PLVEd (6,0 [5,7-6,2] cm). Os valores para o grupo B foram: SIVd (6,9 [6,5-7,3] cm) and PLVEd (6,5 [6,3-6,8] cm). Não houve diferença entre o grupo C e os grupos A e B; os valores para o grupo C foram: SIVd (6,4 [5,9-6,8] cm) e PLVEd (6,4 [6,1-6,7] cm). Portanto, cães adultos da raça Dachshund possuem espessura maiores de SIVd e PLVEd quando comparados com valores padronizados para outras raças. Quando os animais foram divididos pelo peso (>8 kg e ≥ 8 Kg), houve diferenças significativas para DVEd (2,44±0,26 cm; 2,64±0,27 cm; p>0,001), como também para circunferência torácica (> 45 cm e ≥ 45 cm), com valores de 2,43±0,25 cm e 2,63±0,27 cm (p>0,001). Também foram estabelecidos valores ecocardiográficos para tamanho do átrio esquerdo, nos eixos látero-lateral e ápico-basilar, respectivamente, iguais a 2,24±0,31 cm e 2,17±0,31 cm; bem como os valores de Doppler tecidual do anel valvar mitral lateral: onda E`=0,11±0,02 m/s, onda A´=0,10±0,02 m/s e razões E´/A´=1,12±0,33 m/s e E/E´=5,91±1,21 m/s. Cães adultos e sadios da raça Dachshund podem apresentar prolapso valvar mitral (40,58%). O valor de pressão arterial sistêmica por meio do método Doppler na cauda de cães Dachshund adultos e sadios foi de 134±20 mmHg diferenciando-se estatisticamente (p > 0,0001) dos valores obtidos no membro torácico (155±28 mmHg). / Dachshund dogs present achondroplasia/hypochondroplasia, considered a breed physiological condition, that results in a long body with short, arched and muscular limbs, large sternum, oval and wide ribcage and developed heart and lungs. All this factors can difficult exams realization and interpretation. The hypothesis is that Dachshund dogs have differentiated echocardiographic, electrocardiographic, radiographic, and systolic blood pressure parameters. Therefore, 69 adult and healthy Dachshund dogs were studied (28 [40.6%] males and 41 [59.4%] females); from 18 months to 10 years-old, weighting 8.4±2.3 kg. Echocardiographic, electrocardiographic, radiographic and systemic arterial pressure evaluations were performed. Animals were categorized according to gender, neutered or not, age group (A: >1 a ≤ 3 years, B: >3 a 6 years e C: >6 a ≤ 10 years), weight (< 8 kg e ≥ 8 kg) e thoracic circumference (< 45 cm e ≥ 45 cm). The values of conventional echocardiography, electrocardiography, radiography and systemic arterial pressure were established in Dachshund dogs using the Doppler method. The main echocardiographic results, with a mean and 95% confidence interval were: interventricular septum in diastole IVSd (6.5 [6.3-6.7] cm), left ventricular free wall in diástole - LVFWd (6.3 [6.1-6.4] cm), left ventricular internal diameter in diastole LVIDd (2.5 [2.5-2.6] cm), left ventricular internal diameter LVIDs (1.2 [1.2-1.3] cm), shortening fraction SF (51.32 [49.79-52.84]%), left ventricular ejection fraction LVEF (0.84 [0.82-0.85]). There was no statistical difference for gender or castration. But when dogs were categorized by age, there was a statistically significant difference between groups A and B (p = 0.0073) for IVSd and LVFWd.; and the values for group A were: IVSd (6.2 [5.9-6.5] cm) and LVFWd (6.0 [5.7-6.2] cm). The values for group B were: IVSd (6.9 [6.5-7.3] cm) and LVFWd (6.5 [6.3-6.8] cm). There was no difference between group C and groups A and B; The values for group C were: IVSd (6.4 [5.9-6.8] cm) and LVFWd (6.4 [6.1-6.7] cm). Therefore, adult dogs of the breed Dachshund have thickness of IVSd and LVFWd when compared with values standardized for other breeds. When animals were divided by weight (< 8 kg and ≥ 8 kg), there were significant differences for LVIDd (2.44 ± 0.26 cm, 2.64 ± 0.27 cm, p (< 0.001), as well as for thoracic circumference (< 45 cm and ≥ 45 cm), with values of 2.43 ± 0.25 cm and 2.63 ± 0.27 cm (p < 0.001). Echocardiographic values were also established for left atrial size, on the latero-lateral and apical-basilar axes at 2.24 ± 0.31 cm and 2.17 ± 0.31 cm, respectively. In addition, the tissue Doppler values of the lateral mitral valve ring: E\' wave = 0.11±0.02 m/s, A\' wave = 0.10±0.02 m/s and E\'/A\' ratios = 1,12±0.33 m/s and E/E \'= 5.91±1.21 m/s. Adult and healthy Dachshund dogs may present with mitral valve prolapse (40.58%). The Doppler method in the tail of healthy Dachshund dogs was 134 ± 20 mmHg, statistically different (p < 0.0001) from values obtained in left forelimb (155 ± 28 mmHg).

Introdução: A disfunção atrial esquerda está associada a pior prognóstico em diversas situações clínicas. O método de strain bidimensional do átrio esquerdo permite avaliar de forma direta todas as fases da função atrial. Pouco se conhece sobre o comportamento das fases da função atrial esquerda em pacientes com síndrome coronariana aguda. O objetivo desse estudo foi correlacionar as funções de reservatório, conduto e contração do átrio esquerdo com desfechos adversos cardiovasculares em pacientes com síndrome coronariana aguda sem supradesnivelamento do segmento ST. Método: Esse estudo recrutou prospectivamente 109 pacientes com diagnóstico de infarto agudo do miocárdio sem elevação do segmento ST e de angina instável de risco moderado ou alto pelo escore GRACE para realização de ecocardiograma nas primeiras 72 horas. A função atrial foi avaliada por parâmetros ecocardiográficos convencionais e pelo strain bidimensional obtido pela média das janelas apicais 2 e 4 câmaras. O desfecho primário foi avaliado em até um ano de seguimento e foi composto pelos seguintes eventos adversos: óbito, insuficiência cardíaca nova, nova internação por síndrome coronariana aguda ou por insuficiência cardíaca, angina estável com necessidade de nova intervenção coronariana, arritmia (fibrilação atrial ou taquicardia ventricular) e acidente vascular cerebral. Os desfechos secundários foram os combinados desses eventos. Resultados: As médias do strain de reservatório, conduto e contração foram de 25% ± 8, 12% ± 5 e 12% ± 4, respectivamente. O desfecho primário teve uma incidência de 31,8% em até um ano e apresentou uma correlação significativa com o strain de reservatório (HR= 0,92; IC95% 0,88-0,96; p<0,001), de conduto (HR= 0,87; IC95% 0,81-0,94; p<0,001) e de contração (HR= 0,90; IC95% 0,84-0,98; p=0,011). Análise multivariada envolvendo variáveis clínicas e as de função atrial esquerda demonstraram que o strain de reservatório (p=0,03) e de conduto (p=0,046) se mantiveram significativos como preditores do desfecho primário. O strain de conduto se manteve significativo no desfecho combinado de óbito e insuficiência cardíaca (HR= 0,82; IC95% 0,74-0,91; p<0,001) mesmo após análise multivariada com parâmetros clínicos (p<0,001) e ecocardiográficos (p=0,049). Conclusão: A avaliação da função atrial esquerda por meio do strain bidimensional se correlacionou significativamente com desfechos adversos em pacientes com síndrome coronariana aguda sem elevação do segmento ST. O strain de reservatório e de conduto foram marcadores prognósticos independentes para o desfecho primário quando comparados às variáveis clínicas. Já para o desfecho combinado de óbito e insuficiência cardíaca, o strain de conduto foi um preditor independente mesmo após ajustado para variáveis clínicas e ecocardiográficas. / Background: Left atrial dysfunction is associated with worse prognosis in several clinical situations. The left atrial two-dimensional strain method allows direct evaluation of all phases of atrial function. There are few studies on the behavior of the various stages of left atrial function in patients with acute coronary syndrome. The aim of this study was to correlate the functions of reservoir, conduit and contraction of the left atrium with adverse cardiovascular outcomes in patients with non-ST elevation acute coronary syndrome. Method: This study prospectively recruited 109 patients with a non-ST-segment elevation myocardial infarction and unstable angina with moderate or high risk by GRACE score and echocardiography parameters were collected within the first 72 hours of admission. The atrial function was evaluated by conventional echocardiographic parameters and the two-dimensional strain obtained by the mean of the apical two- and four-chamber views. The primary endpoint was assessed during the 1 year follow-up period and was composed of theses adverse events: death, heart failure, rehospitalization for acute coronary syndrome or heart failure, stable angina requiring new coronary intervention, arrhythmia (atrial fibrillation or ventricular tachycardia) and stroke. Secondary outcomes were those combined for these events. Results: The means of reservoir, conduit and contraction strain were 25% ± 8, 12% ± 5 and 12% ± 4, respectively. The primary endpoint occurred in 31.8% patients during the 1 year follow-up period and had a statistically significant correlation with the reservoir strain (HR = 0.92, 95% CI: 0.88-0.96, p <0.001), conduit strain (HR = 0.87, 95% CI: 0.81-0.94, p <0.001) and contraction strain (HR = 0.90, 95% CI: 0.84-0.98, p = 0.011). Multivariate analysis involving clinical variables and left atrial function showed that the reservoir strain (p = 0.03) and conduit (p = 0.046) were independent predictors of endpoint primary. The conduit strain were statistically significant in the combined outcome of death and heart failure (HR = 0.82, 95% CI: 0.74-0.91, p <0.001) even after multivariate analysis with clinical (p <0.001) and echocardiography parametrs (p = 0.049). Conclusion: Evaluation of left atrial function by two-dimensional strain correlated significantly with adverse outcomes in patients with non-ST elevation acute coronary syndrome. The reservoir and conduit strain were independent prognostic markers for the primary endpoint when compared to clinical parametrs. For the combined outcome of death and heart failure, the conduit strain was an independent predictor even after adjusting for clinical and echocardiographic variables.

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Atrial fibrillation is the most prevalent arrhythmia worldwide and remains one of the major causes of morbidity and mortality. Atrial fibrillation is an arrhythmia that has a various etiology and takes number of clinical forms. Due to the heterogenity of atrial fibrillation, it is necessary to individualize the optimal treatment strategy, ie conservative pharmacological therapy or interventional therapy as catheter ablation. Inncorrect indication of catheter ablation of atrial fibrillation leads to low success rate of the procedure and increases the risk of the procedure. The success rate of catheter ablation of atrial fibrillation depends on many clinical parameters, including the size and volume of the left atrium and the presence of pathological tissue in the atrial myocardium. In everyday practice, echocardiography (2D-echocardiography) is the most dominant method in estimation of the left atrial parameters, for it's simplicity, non- invasiveness, financial costs and the absence of ionizing radiation. Different methods for assesment of left atrial parameters are cardiac CT, cardiac magnetic resonance imaging and methods of 3-D echocardiography or 3-D angiography. The results of the present studies show that in patients with non-valvular atrial fibrillation who are indicated for catheter...

Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia. It shows an increasing prevalence in developed countries with a strong association to cardiovascular risk factors. It has become a major challenge to the healthcare system with a high morbidity and increased AF-related mortality. Recommended treatment approaches favor rhythm control strategies, which aim to restore sinus rhythm. The pathophysiologic concept of atrial fibrillation has evolved towards defining the term atrial myopathy, recognizing inflammation mediated remodeling of the left atrium (LA) as a source for and result of arrhythmogenesis. One of many features of atrial myopathy is the development of left atrial fibrosis by fibro-fatty infiltration. This corresponds to low voltage zones (LVZ), that are characterized by impaired myocardial electrical conduction during invasive electroanatomic mapping. Epicardial adipose tissue (EAT) has been revealed to be a key player in this inflammatory process that nourishes the development of left atrial fibrosis. Traditional cardiovascular risk factors favor the transdifferentiation of EAT towards a pro-inflammatory phenotype. Recently, evidence has proven the positive effect of new generation anti-diabetic drugs like sodium-glucose cotransporter 2 (SGLT-2) inhibitors and glucagon-like peptide-1 (GLP-1) receptor agonists on EAT by inducing a favorable phenotypic shift with local anti-inflammatory effect and potential influence on atrial reverse remodeling. This thesis sought to confirm the ability to predict LVZ from cardiac magnetic resonance (CMR) derived parameters and to describe the differences of left atrial volume and left atrial epicardial adipose tissue volume in AF patients with and without LVZ. Patients with indication for primary AF ablation were prospectively enrolled. CMR imaging sequences included an LA angiography and two different techniques for left atrial epicardial adipose tissue imaging (T1 weighted and fat-water separation DIXON-based), which were compared. Left atrial volume index (LAVi) and left atrial epicardial adipose tissue volume index (LA-EATVi) from the DIXON-based technique proofed to be significant predictors of LVZ presence. No significant results could be obtained for the epicardial adipose tissue quantified from T1 weighted imaging. LA-EATVi(DIXON) was significantly higher in patients with LVZ than without, with a mean difference of 10.13 ± 5.0 ml. The same could be shown for LAVi, with a mean difference of 24.46 ± 8.13 ml. Both parameters were independent of each other. Additionally, it could be shown that higher age and female gender are associated with LVZ occurrence. CMR based quantification of LA-EATVi(DIXON) alone or in combination with other predictive variables of LVZ, like LAVi, age and female gender was able to identify patients at low or high risk of LVZ. In the studied patient population, a combined prediction model of LAVi, LA- EATVi(DIXON), age and female gender provided the highest predictive ability to determine LVZ presence with an area under the curve (AUC) in receiver operating characteristics (ROC) of 0.91. Depending on cutoff selection for the prediction model a high positive or negative predictive value can be achieved, minimizing false results. The clinical implementation of a CMR-based prediction model of LVZ presence as a feature of LA myopathy could have a tremendous impact on treatment decisions. It would allow the selection of patients for fast and easy single shot AF-ablation procedures in case of low LVZ risk, whereas complex and more time-consuming invasive procedures were to be scheduled if relevant LA myopathy is to be suspected.:1. Introduction 1 1.1. Atrial fibrillation 1 1.1.1. Risk factors 3 1.1.2. Left atrial myopathy 4 1.1.2.1. Predictive parameters of LA myopathy and atrial fibrosis 6 1.1.2.2. Imaging methods for left atrial myopathy and fibrosis 6 1.1.4. Current treatment strategies 7 1.1.4.1. Catheter ablation 9 1.2. Epicardial adipose tissue 11 1.2.1. Physiology and pathophysiology of epicardial adipose tissue 14 1.2.2. Role of epicardial adipose tissue in atrial fibrillation 15 1.2.3. Imaging techniques of epicardial adipose tissue 18 2. Objective 21 3. Methods 22 3.2. Imaging protocol 24 3.2.1. Adipose tissue imaging with DIXON approach 24 3.2.2. Adipose tissue imaging with T1 weighted imaging approach 26 3.2.3. Left atrial anatomy imaging 26 3.3. Segmentation and Quantification 27 3.4. Electroanatomic mapping and pulmonary vein isolation procedure 31 3.5. Statistical analysis 33 4. Results 34 4.2. General patient cohort characteristics 34 4.3. Patient characteristics in LVZ subgroups 36 4.4. Selected CMR parameter evaluation 39 4.4.1. Left atrial volume 39 4.4.2. Left atrial epicardial adipose tissue volume 41 4.4.2.1. DIXON based left atrial epicardial adipose tissue imaging 41 4.4.2.2. T1 weighted left atrial epicardial adipose tissue imaging 43 4.4.3. Comparison of adipose tissue imaging techniques 45 4.4.4. Reliability analysis 48 4.5. LVZ prediction models 49 4.5.1. Univariate non-CMR based LVZ prediction models 51 4.5.2. Univariate CMR based LVZ prediction models 53 4.5.3. Multivariate LVZ prediction models 57 4.5.4. Example of clinical application 62 4.5.5. Prediction model validation 64 5. Discussion 66 5.2. General aspects 66 5.3. EAT image acquisition 68 5.4. Clinical relevance 68 5.5. Future developments 70 5.6. Limitations 72 6. Summary 74 7. Zusammenfassung 76 8. References 78 9. List of figures and tables 98 10. Acknowledgement 102 11. Curriculum vitae 103 / Vorhofflimmern (AF) ist die häufigste Herzrhythmusstörung. In den Industrieländern nimmt die Prävalenz zu, wobei ein enger Zusammenhang mit kardiovaskulären Risikofaktoren besteht. Vorhofflimmern ist zu einer großen Herausforderung für das Gesundheitssystem geworden, da es eine hohe Morbidität und eine erhöhte vorhofflimmerbedingte Mortalität aufweist. Die empfohlenen Behandlungsansätze favorisieren Rhythmuskontrollstrategien, die auf die Wiederherstellung des Sinusrhythmus abzielen. Das pathophysiologische Konzept des Vorhofflimmerns hat sich dahingehend weiterentwickelt, dass der Begriff Vorhofmyopathie definiert wurde, wobei unter anderem der entzündungsbedingte Umbau (Remodeling) des linken Vorhofs (LA) als eine Ursache und Folge der Arrhythmogenese anerkannt wird. Eines der vielen Merkmale der Vorhofmyopathie ist die Entwicklung einer Fibrose im Bereich des linken Vorhofs durch fibrös-fettige Infiltration. Dies entspricht Niederspannungszonen (LVZ), die bei invasiven elektroanatomischen Kartierungen durch eine beeinträchtigte elektrische Leitung des Myokards gekennzeichnet sind. Es hat sich gezeigt, dass epikardiales Fettgewebe (EAT) eine Schlüsselrolle in diesem entzündlichen Prozess spielt, der die Entwicklung einer linksatrialen Fibrose begünstigt. Traditionelle kardiovaskuläre Risikofaktoren verursachen die Transdifferenzierung des epikardialen Fettgewebes in Richtung eines pro-inflammatorischen Phänotyps. In letzter Zeit hat sich gezeigt, dass Antidiabetika der neuen Generation, wie z. B. Natrium-Glukose-Cotransporter-2-Inhibitoren (SGLT-2) und Glucagon-like Peptide-1 (GLP-1) Rezeptor Agonisten, eine positive Wirkung auf EAT haben, indem sie eine günstige phänotypische Verschiebung mit lokaler Entzündungshemmung und potenziellem Einfluss auf ein „reverses Remodeling“ des Vorhofs bewirken. Ziel dieser Arbeit war es, die Fähigkeit der Vorhersage von LVZ anhand von Parametern aus der kardialen Magnetresonanztomographie (CMR) zu bestätigen und die Unterschiede des Volumens des linken Vorhofs und des linksatrialen epikardialen Fettgewebes bei Vorhofflimmerpatienten mit und ohne LVZ zu beschreiben. Patienten mit Indikation zur primären Vorhofflimmerablation wurden prospektiv eingeschlossen. Zu den akquirierten CMR-Bildgebungssequenzen zählte eine LA- Angiographie und zwei verschiedene Techniken zur Darstellung des linksatrialen epikardialen Fettgewebes (T1-gewichtet und Fett-Wasser-Trennung auf DIXON-Basis). Letztere wurden miteinander verglichen. Der Volumenindex des linken Vorhofs (LAVi) und der Volumenindex des linksatrialen epikardialen Fettgewebes (LA-EATVi) aus der DIXON-basierten Bildgebung erwiesen sich als signifikante Prädiktoren für das Vorhandensein von LVZ. Für das epikardiale Fettgewebe, das mit der T1-gewichteten Bildgebung quantifiziert wurde, konnten keine signifikanten Ergebnisse erzielt werden. LA-EATVi(DIXON) war bei Patienten mit LVZ signifikant höher als bei Patienten ohne LVZ, mit einer mittleren Differenz von 10.13 ± 5.0 ml. Dasselbe konnte für LAVi gezeigt werden, mit einer mittleren Differenz von 24.46 ± 8.13 ml. Beide Parameter waren unabhängig voneinander. Außerdem konnte gezeigt werden, dass höheres Alter und weibliches Geschlecht mit dem Auftreten von LVZ assoziiert sind. Die CMR-basierte Quantifizierung von LA-EATVi(DIXON) allein oder in Kombination mit anderen prädiktiven Variablen für LVZ, wie LAVi, Alter und weiblichem Geschlecht, war in der Lage, Patienten mit niedrigem oder hohem Risiko für LVZ zu identifizieren. In der untersuchten Patientenpopulation lieferte ein kombiniertes Vorhersagemodell aus LAVi, LA-EATVi(DIXON), Alter und weiblichem Geschlecht die höchste Vorhersagekraft zur Bestimmung des Vorhandenseins von LVZ mit einer Fläche unter der Kurve (AUC) in der Grenzwertoptimierungskurve (ROC) von 0.91. Je nach Auswahl des Cutoffs für das Vorhersagemodell kann ein hoher positiver oder negativer Vorhersagewert erreicht werden, wodurch falsche Ergebnisse minimiert werden. Die klinische Umsetzung eines CMR-basierten Vorhersagemodells für das Vorhandensein von LVZ als Merkmal der LA-Myopathie könnte sich enorm auf die Behandlungsentscheidungen auswirken. Es würde die Auswahl von Patienten für schnelle und einfache Single-Shot-Ablationsverfahren bei geringem LVZ-Risiko ermöglichen, während bei Verdacht auf eine relevante LA-Myopathie komplexe und zeitaufwändigere invasive Verfahren geplant werden müssten.:1. Introduction 1 1.1. Atrial fibrillation 1 1.1.1. Risk factors 3 1.1.2. Left atrial myopathy 4 1.1.2.1. Predictive parameters of LA myopathy and atrial fibrosis 6 1.1.2.2. Imaging methods for left atrial myopathy and fibrosis 6 1.1.4. Current treatment strategies 7 1.1.4.1. Catheter ablation 9 1.2. Epicardial adipose tissue 11 1.2.1. Physiology and pathophysiology of epicardial adipose tissue 14 1.2.2. Role of epicardial adipose tissue in atrial fibrillation 15 1.2.3. Imaging techniques of epicardial adipose tissue 18 2. Objective 21 3. Methods 22 3.2. Imaging protocol 24 3.2.1. Adipose tissue imaging with DIXON approach 24 3.2.2. Adipose tissue imaging with T1 weighted imaging approach 26 3.2.3. Left atrial anatomy imaging 26 3.3. Segmentation and Quantification 27 3.4. Electroanatomic mapping and pulmonary vein isolation procedure 31 3.5. Statistical analysis 33 4. Results 34 4.2. General patient cohort characteristics 34 4.3. Patient characteristics in LVZ subgroups 36 4.4. Selected CMR parameter evaluation 39 4.4.1. Left atrial volume 39 4.4.2. Left atrial epicardial adipose tissue volume 41 4.4.2.1. DIXON based left atrial epicardial adipose tissue imaging 41 4.4.2.2. T1 weighted left atrial epicardial adipose tissue imaging 43 4.4.3. Comparison of adipose tissue imaging techniques 45 4.4.4. Reliability analysis 48 4.5. LVZ prediction models 49 4.5.1. Univariate non-CMR based LVZ prediction models 51 4.5.2. Univariate CMR based LVZ prediction models 53 4.5.3. Multivariate LVZ prediction models 57 4.5.4. Example of clinical application 62 4.5.5. Prediction model validation 64 5. Discussion 66 5.2. General aspects 66 5.3. EAT image acquisition 68 5.4. Clinical relevance 68 5.5. Future developments 70 5.6. Limitations 72 6. Summary 74 7. Zusammenfassung 76 8. References 78 9. List of figures and tables 98 10. Acknowledgement 102 11. Curriculum vitae 103

Abstrakt: Vänster förmaksstorlek har prognostisk betydelse inom kardiologi. Det finns generellt enighet om att vänster förmaksvolymmätning (VFV) är det bästa mätmåttet av vänster förmaksstorlek. För närvarande används S5-1 som är en phased array givare, som första val, för att avbilda 2-dimensionella två- och fyrkammarvyer. Matrix array givaren X5-1 är ett praktiskt kliniskt alternativ för insamling av samma 2D projektioner men den har inte utvärderats på ett adekvat sätt mot S5-1 givare avseende VFV. Syftet med studien är att undersöka om det föreligger någon statistisk signifikant skillnad vid bestämning av VFV i apikal tvåkammarvy beroende på val av givare. Studien omfattade 50 patienter som var remitterade för en ekokardografisk undersökning på avdelningen för klinisk fysiologi och nuklearmedicin på Skånes Universitetssjukhus i Malmö. Ekokardiografiska bilder, insamlades med båda givarna, från både patienter med normal och abnormal vänster förmaksstorlek som hade sinusrytm. VFV mättes med Simpsons biplanmetod efter gällande amerikanska och europeiska riktlinjer. Det fanns en signifikant korrelation mellan medelvärdet av VFV, mätta på bilder som erhållits med de två olika insamlingsmetoderna (r =0,98, P 0,0001). Den utförda Bland-Altmananalysen visade också en statistiskt signifikant överensstämmelse i VFV mätning mellan de två insamlingsmetoderna. Studien visade att X5-1 givaren kan vara ett praktiskt alternativ för att erhålla 2D tvåkammarprojektion på ett mer tidseffektivt sätt jämfört med S5-1 givaren. / Abstract: Left atrial size has a prognostic significance in cardiology.There is ecumenical agreement that measurement of left atrial volume (LAV) is the best way to evaluate the left atrial size. Currently, S5-1, a phased array transducer, is used as the first choice to depict the 2-dimensional (2D) two- and four apical chamber views. X5-1, a matrix array transducer, is a practical clinical option for collecting the same 2D projections, but it has not been adequately assessed against the S5-1 transducer with LAV in consideration. The purpose of the present study was to investigate whether there is any statistically significant difference in the determination of LAV in apical two chamber views depending on the choice of transducer. The study included 50 patients who were referred for an echocardiographic examination at the Department of Clinical Physiology and Nuclear Medicine at Skåne University Hospital in Malmö. Echocardiographic images collected with both transducers, from patients with both normal and abnormal left atrial sizes and with sinus rhythm. LAV was measured using Simpson's biplane method according to the current American Society of Echocardiography (ASE) and European Association of Cardiovascular Imaging (EACVI) guidelines. There was a significant correlation between the mean of LAV, measured in images obtained by the two different transducers (r = 0.98, P 0.0001). The Bland-Altman analysis showed a statistically significant agreement in LAV measurement between the two methods. The X5-1 transducer is possibly a practical alternative to obtain 2D apical two-chamber projection in a more time efficient manner compared to the S5-1 transducer.