No description available.

Nous avons développé des méthodes de traitement d’image et de fusion multimodalité et les avons appliqué à l’étude des relations structure-fonction dans la fibrillation auriculaire et la tachycardie ventriculaire. Dans la fibrillation auriculaire, nos résultats indiquent que le rehaussement tardif par IRM est fortement associé à présence et à la persistance d’une fibrillation auriculaire. Nous avons par ailleurs démontré que ce rehaussement tardif est associé à des caractéristiques électrophysiologiques propres : le signal fibrillatoire est plus lent et moins fragmenté au sein des zones rehaussées, alors qu’à l’inverse la complexité globale de la fibrillation augmente avec l’étendue des rehaussements. Nos résultats préliminaires sur la distribution des rotors vont dans le même sens, ces derniers étant plus volontiers observés à la périphérie des zones rehaussées, et le nombre de régions actives augmentant avec l’étendue des rehaussements. L’ensemble de ces résultats confirme que l’imagerie de rehaussement tardif par IRM permet une caractérisation du tissu atrial. Dans les arythmies ventriculaires, nous avons développé une stratégie permettant l’intégration systématique de données non-invasives multimodales au cours des procédures d’ablation de tachycardie ventriculaire. Nous avons démontré l’intérêt d’une fusion scanner et IRM, et décrit une méthode permettant l’intégration du substrat ischémique à partir de données scanner applicable chez les patient porteurs de défibrillateurs ne pouvant bénéficier de l’IRM. Dans la dysplasie arythmogène du ventricule droit, nous avons introduit une méthode automatique de quantification et de cartographie du substrat dysplasique applicable au diagnostic et au guidage thérapeutique. Enfin, nous avons introduit une méthode d’exploration multimodale des arythmies cardiaques intégrant la cartographie électrocardiographique 3D aux autres méthodes d’imagerie cardiaque, et permettant une exploration non invasive simultanée de l’anatomie, du substrat, et des mécanismes de l’arythmie / We have developed and applied image-processing methods to the study of structure-function relationships in atrial fibrillation and ventricular tachycardia. In Atrial Fibrillation, our results indicate that the late gadolinium enhancement observed with the use of MRI is strongly associated with the presence and persistence of the disease. In addition, we have demonstrated that these enhancements show distinctive electrophysiological characteristics: the fibrillatory signal is slower and less fractionated within enhanced areas, whereas the global complexity of atrial fibrillation is conversely increasing with the extent of enhancement. Our preliminary results on rotor distribution are consistent, rotors being more likely found at the border of enhanced areas, and the number of regions with high rotor activity being positively related to the extent of enhancement. These results confirm that late gadolinium enhancement MRI enables a non-invasive characterization of the atrial tissue. In Ventricular Arrhythmias, we have developed a strategy to integrate multimodal non-invasive data during ventricular tachycardia ablation procedures. We have demonstrated the value of fusing MDCT and MRI data and have introduced a method enabling the integration of ischemic substrate from MDCT data, feasible in patients with implantable defibrillator who cannot undergo MRI. In arrhythmogenic right ventricular cardiomyopathy, we have developed an automatic method for the mapping and quantification of fat in the right ventricular free wall based on MDCT data, and have successfully applied the method to the diagnosis and therapy guidance of the disease. Last, we have introduced a method for the multimodal assessment of cardiac arrhythmias combining electrocardiographic mapping with MDCT and MRI. The method enables a non-invasive and combined assessment of cardiac anatomy, myocardial structural substrate, and arrhythmia mechanisms.

A estratificação de risco para morte súbita em pacientes com cardiomiopatia hipertrófica ainda é um desafio. Sua prevenção pelo cardiodesfibrilador automático é eficaz, porém, onerosa e não isenta de riscos. Pacientes com indicação de cardiodesfibrilador automático para prevenção primária, baseada em fatores de risco clínicos, apresentam baixa taxa de terapias apropriadas. Estudos que validem novos fatores de risco são necessários, visando identificar pacientes com maior probabilidade de morte súbita e, portanto, que se beneficiam do implante do dispositivo. Estudos que correlacionam a presença de realce tardio com arritmias ventriculares e morte súbita foram realizados, entretanto, sua aplicabilidade clinica ainda não é consenso. Objetivos: Avaliar, em portadores de cardiomiopatia hipertrófica, se a presença e a extensão de realce tardio, identificado pela tomografia computadorizada, correlaciona-se com a ocorrência de taquiarritmias ventriculares registradas no monitor de eventos do cardiodesfibrilador automático, durante um seguimento clínico ambulatorial. Métodos: Foram incluídos pacientes com cardiomiopatia hipertrófica dos ambulatórios de Eletrofisiologia e Miocardiopatias do Instituto Dante Pazzanese de Cardiologia. Os pacientes foram divididos em dois grupos: grupo I composto por aqueles que receberam terapia apropriada pelo cardiodesfibrilador automático ou tiveram apenas a documentação de taquicardia ventricular não sustentada pelo cardiodesfibrilador automático; grupo II, composto por pacientes sem documentação de arritmias ventriculares no monitor de eventos. As variáveis contínuas foram comparadas utilizando-se testes t de Student pareado ou Wilcoxon; para as categóricas o teste do x2. Para análise dos dados, utilizou-se o programa SPSS. Valores de p < 0,05 foram considerados estatisticamente significativos. Resultados: Sessenta e um pacientes (idade média 39±15 anos, 51% mulheres, com seguimento médio 5,13±3,0 anos) foram avaliados. Em 91,8%, a indicação do cardiodesfibrilador automático foi por prevenção primária. Durante o seguimento clínico, cinco pacientes (8,2%) apresentaram terapias apropriadas e 15 (24,6%) tiveram taquicardia ventricular não sustentada, mas sem terapia. A densidade de fibrose (incluindo massa de ventrículo esquerdo acometida e percentual de acometimento) não foi estatisticamente diferente entre os grupos I e II (4,3±4,8% vs 7,0±7,7% nos grupos I e II, respectivamente, p = 0,13). Entretanto, 85% dos pacientes com taquicardia ventricular apresentavam fibrose à tomografia computadorizada. Maiores densidades de fibrose se correlacionaram com idades mais jovens, com menores frações de ejeção e sexo masculino. Espessura septal >= 30mm se correlacionou à maior massa de fibrose. Houve correlação entre o surgimento de fibrilação atrial e maior porcentual de fibrose do ventrículo esquerdo. Dentre os fatores que se correlacionaram com maior densidade de fibrose, nenhum deles se correlacionou com eventos arrítmicos ventriculares. A associação dos fatores clínicos ou fatores clínicos isolados que motivaram a indicação do implante do cardiodesfibrilador automático não se correlacionou com eventos arrítmicos. Os pacientes do grupo I apresentaram maior diâmetro diastólico do ventrículo esquerdo e maior diâmetro do átrio esquerdo quando comparado com os pacientes do grupo II (47,7±4,7mm vs 43.1±5,4 mm, p = 0,002 e 47,8±8mm vs 41,5±7,1mm, p = 0,003, respectivamente). Conclusões: 1. A presença de fibrose detectada pela tomografia computadorizada apresenta razoável sensibilidade para identificação de pacientes com risco para taquicardia ventricular; 2. A densidade de fibrose foi similar nos pacientes dos grupos I e II; 3. Pacientes com fibrilação atrial apresentaram maior densidade de fibrose ventricular detectada pela tomografia computadorizada em comparação aos pacientes sem fibrilação atrial; 4. O diâmetro diastólico final de ventrículo esquerdo e o diâmetro atrial esquerdo associaram-se à maior risco de taquicardia ventricular; 5. Os fatores de risco convencionais, associados ou não à fibrose, não se correlacionaram com maior probabilidade de ocorrência de eventos arrítmicos ventriculares. / Risk stratification for sudden cardiac death in hypertrophic cardiomyopathy patients is still challenging. Primary prevention of sudden death with implantable cardioverter-defibrillator is an effective, however, costly and not risk-free method. Patients with implantable cardioverter-defibrillator indicated for primary prevention based on clinical risk factors display low rates of appropriate therapies. Studies evaluating new risk factors are needed seeking to identify who would be mostly at risk of sudden cardiac death, and therefore benefit from cardioverter-defibrillator. Studies have been conducted to establish a correlation between late enhancement and ventricular arrhythmias and sudden cardiac death; however, its clinical applicability is still controversial. Objective: To evaluate if the presence and extension of late enhancement, identified by computed tomography, correlates with the occurrence of ventricular arrhythmias in hypertrophic cardiomyopathy patients. Methods: Patients with hypertrophic cardiomyopathy followed in Electrophysiology and Cardiomyopathies divisions at Dante Pazzanese Institute of Cardiology were included in the study. Patients were divided into two groups: group I composed by those with appropriate therapies (shock or overdrive) or non-sustained ventricular tachycardia; and group II, composed by patients without documented ventricular arrhythmias. Continuous variables were compared using paired t-student test or Wilcoxon test. Categorical variables were analyzed using chi-square test. For data analysis, the SPSS program was used. P values < 0.05 were considered statistically significant. Results: Sixty one patients (mean age 39 ± 15 years, 51% female, average follow up 5.13 ± 3 years) were evaluated. In 91.8%, cardioveter-defibrillator was indicated by primary prevention. During the follow up, five patients (8.2%) had appropriate therapies and 15 (24.6%) presented non-sustained ventricular tachycardia without therapies. Fibrosis density, (including left ventricular mass compromise and percentage) was not statistically different between the groups (4.3±4.8% for group I vs. 7.0±7.7% for group II, p =0.13). However, 85% of patients with ventricular tachycardia had fibrosis on cardiac computed tomography. Larger fibrosis density correlated with younger age, reduced ejection fraction and male gender. Septum >30 mm correlated with fibrosis mass. There was a correlation between atrial fibrillation and higher left ventricular fibrosis percentage. Among the factors that correlated with higher fibrosis density, none of them had correlation with ventricular arrhythmic events. The combination of clinical factors that motivated the implantation of cardioverter-defibrillator did not correlate with arrhythmic events. Patients at group I had larger left ventricular diastolic diameter (47.7±4.7 vs. 43.1±5.4mm, respectively, p= 0.002) and left atrium diameter (47.8±8.2 vs. 41.5±7.1 mm, respectively, p=0.003). Conclusions: 1. The presence of fibrosis detected by cardiac tomography had reasonable sensitivity to identify patients at risk of ventricular tachycardia; 2. Fibrosis density was similar between groups I and II; 3. Patients with atrial fibrillation had more fibrosis density detected by cardiac tomography compared to patients without atrial fibrillation; 4. Left ventricular end diastolic diameter and left atrial diameter correlated with increased risk of ventricular tachycardia; 5. Classical risk factors, associated or not with fibrosis, did not correlate with increased probability of ventricular arrhythmic events.

This thesis describes the electrical and physiological characterization of cardiac tissue with myocardial infarction (MI) responsible for abnormal cardiac rhythms such as ventricular tachycardia (VT), using a newly-developed magnetic resonance imaging (MRI) electrophysiology system. In electrophysiology (EP), radiofrequency (RF) catheter ablation combined with cardioverter-defibrillator implantation is a first-line action to manage ventricular VT. Unfortunately, this therapy is known to have sub-optimal success rates in a large number of patients because of difficulties to accurately identifying the arrhythmic target regions. Currently, characterization of post-MI scars is performed by using catheters to measure electrical signals of the endocardial tissue (electroanatomical mapping), under x-ray fluoroscopy guidance. Prolonged radiation exposure to both the cardiologist and the patient have made the use of MRI extremely attractive; further, unlike x-ray imaging, MRI provides post-MI scars with direct visualization, characterization in three dimensions and the ability to visualize ablation lesions. Although recent research has focused on registration between pre-acquired MR images and electroanatomical maps, a potentially more useful approach is to use real-time MRI to directly locate and characterize potential arrhythmogenic regions during the EP procedure. A real-time MR-guided EP system was developed and validated to perform EP diagnostic procedures, such as mapping and pacing. In a series of animal studies, the system demonstrated the ability to use active catheter tracking and intra-procedural MR imaging to navigate to specific regions in the left ventricle and record intracardiac electrical signals. A study correlating myocardial fibrotic scar detected by multicontrast late enhancement (MCLE) MRI and electroanatomical voltage mapping demonstrated that MRI information (transmurality, tissue classification, and relaxation rate) can accurately predict areas of myocardial fibrosis identified with bipolar voltage mapping. Finally, MCLE-derived gray zone was shown to have a high correspondence to regions with a high proportion of abnormal intracardiac signals. The methods described in this thesis help advance the understanding of infarcted tissue responsible for ventricular tachycardia. Further studies are proposed to perform RF ablation lesions and correlate pre- and post-ablation tissue electrophysiological properties with MRI.

Šiame darbe apžvelgiama Vilniaus Universiteto Širdies ligų ir kraujagyslių klinikoje 1991−2008 metais sukaupta patirtis taikant nemedikamentinį gydymą pacientams su supraventrikulinėmis tachikardijomis ir skilveliniais ritmo sutrikimais. Apibendrinome nemedikamentinio gydymo rezultatus 1693 pacientams: 753 pacientams su atrioventrikulinio mazgo paroksizmine tachikardija, 657 pacientams su papildomais laidumo takais, 169 pacientams su skilvelinėmis tachikardijomis. Be to, apibendrinome kardioverterių defibriliatorių implantavimo rezultatus 118 pacientų. Nustatėme, kad atrioventrikulinio mazgo tachikardijos kateterinės abliacijos efektyvumas 99,2%, komplikacijų dažnis 0,53%. Įrodėme, kad saugu atlikti „lėtos“ zonos abliaciją pacientams su ilgu PQ intervalu. Papildomų laidumo takų kateterinė abliacija buvo efektyvi 98,1% atvejų, komplikacijų dažnis 1,7%. Papildomų laidumo takų grupėje sudėtingiausios lokalizacijos yra užpakalinė pertvarinė dalis ir vidurinė pertvarinė dalis (pastaroji – dėl rizikos sukelti III laipsnio AV blokadą). Skilvelinių tachikardijų kateterinės abliacijos rezultatas priklauso nuo etiologijos. „Idiopatinių“ skilvelinių tachikardijų atvejais kateterinės abliacijos efektyvumas viršija 90%. Koronarinės širdies ligos ir kardiomiopatijų atvejais kateterinė abliacija mažiau efektyvi (~60%). Kardioverterių defibriliatorių grupėje iki 11 m. stebint pacientus, defibriliatorius suveikė 68,6% atvejų. / This paper reviews the 1991−2008 experience with non-pharmacological treatment of supraventricular and ventricular tachycardias in the Clinic of Heart and vessel diseases of Vilnius University. We summarized the results of managing 1693 patients: 753 patients with atrioventricular nodal tachycardia, 657 patients with accessory pathways, 169 patients with ventricular tachycardias, and 118 patients with implanted cardioverter defibrillators. We have shown that the success rate of catheter ablation for atrioventricular nodal tachycardia is 99.2% with complication rate 0.53%. The safety of ablating the “slow” pathway in patients with prolonged PQ interval has been shown. The success rate of catheter ablation of accessory pathways is 98.1% with 1.7% complication rate. The most complex accessory pathway localization for ablation was posteroseptal area and midseptal area (the latter because of the risk to induce a complete atrioventricular block). The result of catheter ablation for ventricular tachycardia depends on etiology. For “idiopathic” ventricular tachycardias success rate exceeds 90%. In patients with coronary heart disease and cardiomyopathies, catheter ablation is less effective (60%). During the follow-up with duration up to 11 years, 68.6% of patients with implanted cardioverter defibrillators have experienced therapy delivered by the device.

This thesis describes the electrical and physiological characterization of cardiac tissue with myocardial infarction (MI) responsible for abnormal cardiac rhythms such as ventricular tachycardia (VT), using a newly-developed magnetic resonance imaging (MRI) electrophysiology system. In electrophysiology (EP), radiofrequency (RF) catheter ablation combined with cardioverter-defibrillator implantation is a first-line action to manage ventricular VT. Unfortunately, this therapy is known to have sub-optimal success rates in a large number of patients because of difficulties to accurately identifying the arrhythmic target regions. Currently, characterization of post-MI scars is performed by using catheters to measure electrical signals of the endocardial tissue (electroanatomical mapping), under x-ray fluoroscopy guidance. Prolonged radiation exposure to both the cardiologist and the patient have made the use of MRI extremely attractive; further, unlike x-ray imaging, MRI provides post-MI scars with direct visualization, characterization in three dimensions and the ability to visualize ablation lesions. Although recent research has focused on registration between pre-acquired MR images and electroanatomical maps, a potentially more useful approach is to use real-time MRI to directly locate and characterize potential arrhythmogenic regions during the EP procedure. A real-time MR-guided EP system was developed and validated to perform EP diagnostic procedures, such as mapping and pacing. In a series of animal studies, the system demonstrated the ability to use active catheter tracking and intra-procedural MR imaging to navigate to specific regions in the left ventricle and record intracardiac electrical signals. A study correlating myocardial fibrotic scar detected by multicontrast late enhancement (MCLE) MRI and electroanatomical voltage mapping demonstrated that MRI information (transmurality, tissue classification, and relaxation rate) can accurately predict areas of myocardial fibrosis identified with bipolar voltage mapping. Finally, MCLE-derived gray zone was shown to have a high correspondence to regions with a high proportion of abnormal intracardiac signals. The methods described in this thesis help advance the understanding of infarcted tissue responsible for ventricular tachycardia. Further studies are proposed to perform RF ablation lesions and correlate pre- and post-ablation tissue electrophysiological properties with MRI.

A estratificação de risco para morte súbita em pacientes com cardiomiopatia hipertrófica ainda é um desafio. Sua prevenção pelo cardiodesfibrilador automático é eficaz, porém, onerosa e não isenta de riscos. Pacientes com indicação de cardiodesfibrilador automático para prevenção primária, baseada em fatores de risco clínicos, apresentam baixa taxa de terapias apropriadas. Estudos que validem novos fatores de risco são necessários, visando identificar pacientes com maior probabilidade de morte súbita e, portanto, que se beneficiam do implante do dispositivo. Estudos que correlacionam a presença de realce tardio com arritmias ventriculares e morte súbita foram realizados, entretanto, sua aplicabilidade clinica ainda não é consenso. Objetivos: Avaliar, em portadores de cardiomiopatia hipertrófica, se a presença e a extensão de realce tardio, identificado pela tomografia computadorizada, correlaciona-se com a ocorrência de taquiarritmias ventriculares registradas no monitor de eventos do cardiodesfibrilador automático, durante um seguimento clínico ambulatorial. Métodos: Foram incluídos pacientes com cardiomiopatia hipertrófica dos ambulatórios de Eletrofisiologia e Miocardiopatias do Instituto Dante Pazzanese de Cardiologia. Os pacientes foram divididos em dois grupos: grupo I composto por aqueles que receberam terapia apropriada pelo cardiodesfibrilador automático ou tiveram apenas a documentação de taquicardia ventricular não sustentada pelo cardiodesfibrilador automático; grupo II, composto por pacientes sem documentação de arritmias ventriculares no monitor de eventos. As variáveis contínuas foram comparadas utilizando-se testes t de Student pareado ou Wilcoxon; para as categóricas o teste do x2. Para análise dos dados, utilizou-se o programa SPSS. Valores de p < 0,05 foram considerados estatisticamente significativos. Resultados: Sessenta e um pacientes (idade média 39±15 anos, 51% mulheres, com seguimento médio 5,13±3,0 anos) foram avaliados. Em 91,8%, a indicação do cardiodesfibrilador automático foi por prevenção primária. Durante o seguimento clínico, cinco pacientes (8,2%) apresentaram terapias apropriadas e 15 (24,6%) tiveram taquicardia ventricular não sustentada, mas sem terapia. A densidade de fibrose (incluindo massa de ventrículo esquerdo acometida e percentual de acometimento) não foi estatisticamente diferente entre os grupos I e II (4,3±4,8% vs 7,0±7,7% nos grupos I e II, respectivamente, p = 0,13). Entretanto, 85% dos pacientes com taquicardia ventricular apresentavam fibrose à tomografia computadorizada. Maiores densidades de fibrose se correlacionaram com idades mais jovens, com menores frações de ejeção e sexo masculino. Espessura septal >= 30mm se correlacionou à maior massa de fibrose. Houve correlação entre o surgimento de fibrilação atrial e maior porcentual de fibrose do ventrículo esquerdo. Dentre os fatores que se correlacionaram com maior densidade de fibrose, nenhum deles se correlacionou com eventos arrítmicos ventriculares. A associação dos fatores clínicos ou fatores clínicos isolados que motivaram a indicação do implante do cardiodesfibrilador automático não se correlacionou com eventos arrítmicos. Os pacientes do grupo I apresentaram maior diâmetro diastólico do ventrículo esquerdo e maior diâmetro do átrio esquerdo quando comparado com os pacientes do grupo II (47,7±4,7mm vs 43.1±5,4 mm, p = 0,002 e 47,8±8mm vs 41,5±7,1mm, p = 0,003, respectivamente). Conclusões: 1. A presença de fibrose detectada pela tomografia computadorizada apresenta razoável sensibilidade para identificação de pacientes com risco para taquicardia ventricular; 2. A densidade de fibrose foi similar nos pacientes dos grupos I e II; 3. Pacientes com fibrilação atrial apresentaram maior densidade de fibrose ventricular detectada pela tomografia computadorizada em comparação aos pacientes sem fibrilação atrial; 4. O diâmetro diastólico final de ventrículo esquerdo e o diâmetro atrial esquerdo associaram-se à maior risco de taquicardia ventricular; 5. Os fatores de risco convencionais, associados ou não à fibrose, não se correlacionaram com maior probabilidade de ocorrência de eventos arrítmicos ventriculares. / Risk stratification for sudden cardiac death in hypertrophic cardiomyopathy patients is still challenging. Primary prevention of sudden death with implantable cardioverter-defibrillator is an effective, however, costly and not risk-free method. Patients with implantable cardioverter-defibrillator indicated for primary prevention based on clinical risk factors display low rates of appropriate therapies. Studies evaluating new risk factors are needed seeking to identify who would be mostly at risk of sudden cardiac death, and therefore benefit from cardioverter-defibrillator. Studies have been conducted to establish a correlation between late enhancement and ventricular arrhythmias and sudden cardiac death; however, its clinical applicability is still controversial. Objective: To evaluate if the presence and extension of late enhancement, identified by computed tomography, correlates with the occurrence of ventricular arrhythmias in hypertrophic cardiomyopathy patients. Methods: Patients with hypertrophic cardiomyopathy followed in Electrophysiology and Cardiomyopathies divisions at Dante Pazzanese Institute of Cardiology were included in the study. Patients were divided into two groups: group I composed by those with appropriate therapies (shock or overdrive) or non-sustained ventricular tachycardia; and group II, composed by patients without documented ventricular arrhythmias. Continuous variables were compared using paired t-student test or Wilcoxon test. Categorical variables were analyzed using chi-square test. For data analysis, the SPSS program was used. P values < 0.05 were considered statistically significant. Results: Sixty one patients (mean age 39 ± 15 years, 51% female, average follow up 5.13 ± 3 years) were evaluated. In 91.8%, cardioveter-defibrillator was indicated by primary prevention. During the follow up, five patients (8.2%) had appropriate therapies and 15 (24.6%) presented non-sustained ventricular tachycardia without therapies. Fibrosis density, (including left ventricular mass compromise and percentage) was not statistically different between the groups (4.3±4.8% for group I vs. 7.0±7.7% for group II, p =0.13). However, 85% of patients with ventricular tachycardia had fibrosis on cardiac computed tomography. Larger fibrosis density correlated with younger age, reduced ejection fraction and male gender. Septum >30 mm correlated with fibrosis mass. There was a correlation between atrial fibrillation and higher left ventricular fibrosis percentage. Among the factors that correlated with higher fibrosis density, none of them had correlation with ventricular arrhythmic events. The combination of clinical factors that motivated the implantation of cardioverter-defibrillator did not correlate with arrhythmic events. Patients at group I had larger left ventricular diastolic diameter (47.7±4.7 vs. 43.1±5.4mm, respectively, p= 0.002) and left atrium diameter (47.8±8.2 vs. 41.5±7.1 mm, respectively, p=0.003). Conclusions: 1. The presence of fibrosis detected by cardiac tomography had reasonable sensitivity to identify patients at risk of ventricular tachycardia; 2. Fibrosis density was similar between groups I and II; 3. Patients with atrial fibrillation had more fibrosis density detected by cardiac tomography compared to patients without atrial fibrillation; 4. Left ventricular end diastolic diameter and left atrial diameter correlated with increased risk of ventricular tachycardia; 5. Classical risk factors, associated or not with fibrosis, did not correlate with increased probability of ventricular arrhythmic events.

L’ablation par radiofréquence percutanée est un des traitements des tachycardiesventriculaires (TV). Bien que salvateur chez certains patients avec myocardiopathie (MCP),les taux de succès rapportés varient de 53 à 67% dans les centres entrainés.Le but de ce travail est d’essayer de mieux comprendre le substrat des arythmiesventriculaires et d’en améliorer le traitement. Pour cela, nous avons étudié le substrat despatients adressés pour ablation de TV (sur MCP ischémique, sur MCP dilatée à coronairessaines avec cicatrices sous épicardiques, chez les patients avec assistance ventriculairegauche et chez un patient avec syndrome de Brugada). Nous avons également évalué etproposé des outils/attitudes thérapeutiques pour essayer d’améliorer le traitement des TV.Nous avons mis en évidence des particularités électrophysiologiques pour chacun de cessubstrats qui permettent d’optimiser et d’adapter la cartographie et l’ablation chez cespatients. Par ailleurs, nous avons montré l’intérêt : (1) de nouvelles technologies pouraméliorer l’efficacité de l’ablation ; (2) des approches épicardiques ou d’alcoolisation intracoronaire, chez certains patients sélectionnés, qui permettent d’éliminer le substrat et (3)de l’imagerie cardiaque pour mieux identifier le substrat et diminuer les risques perprocédure.La connaissance du substrat spécifique à chaque pathologie, une information sur laforce du contact entre le cathéter et le tissu, l’imagerie cardiaque (scanner et IRM), uneapproche épicardique chez certains patients et l’homogénéisation de la cicatricemyocardique permettent d’être plus efficace lors de l’ablation des TV. / Radiofrequency (RF) catheter ablation is a recognized treatment for ventricular tachycardia(VT) in patients with structural heart disease. Even if it can be life saving, success rateremains around 53 to 67%.We aimed to better characterized VT substrate in patients with ischemic cardiomyopathy(CMP), non ischemic CMP with subepicardial scar, left ventricular assist device and Brugadasyndrome. We also evaluate the efficacy of new technologies (such as contact force), specificapproaches (epicardial access, intra coronary alcohol ablation), systematic use of cardiacimaging and new end-points for VT ablation.We demonstrated that each substrate had specific electrophysiological properties that helpoptimizing the mapping and the ablation in these patients. We also showed the interest of(1) new technologies to improve RF lesion formation; (2) specific approaches in selectedpatients to eradicate the VT substrate; and (3) cardiac imaging to help identifying thesubstrate and preventing complications. Finally using local abnormal ventricular potentialelimination as an end-point for VT ablation is feasible and associated with lower mortalityduring follow-up when achieved.Knowledge of substrate specificities, use of contact force, cardiac imaging, epicardial accessin selected patients and scar homogenization improve VT ablation efficacy and/or safety.

No description available.

<p>  </p> <p><strong>Background: </strong></p> <p>Torsades de pointes (TdP) is a polymorphic ventricular tachycardia (VT) associated with heart rate-corrected QT interval (QTc) prolongation on the electrocardiogram (ECG). TdP can cause sudden cardiac arrest (SCA), a catastrophic outcome. The antiarrhythmic drugs dofetilide and sotalol can cause QTc prolongation and arrhythmias, as can more than 200 other medications available on global markets. Heart failure (HF) with reduced ejection fraction (HFrEF) is a risk factor for drug-induced TdP, and HFrEF heightens sensitivity to drug-induced QTc lengthening. However, ~55% of patients with HF have preserved, rather than reduced, ejection fraction. It remains unknown whether patients with HF with preserved ejection fraction (HFpEF) are at increased risk for drug-induced VT/SCA. Assessment of the risk of drug-induced VT/SCA in HFpEF patients is important, so that recommendations can be made regarding the safety of QTc-prolonging drugs and need for enhanced ECG monitoring in this population. </p> <p><strong>Objective:</strong></p> <p>In aim 1, we sought to determine the risk of VT and SCA associated with dofetilide and sotalol in patients with HFpEF. In aim 2, we were able to use QTc interval to determine the odds of dofetilide/sotalol-associated QT interval prolongation in patients with HFpEF. In Aim 3, we investigated the influence of HFpEF on VT and SCA associated with a broader group of drugs known to cause TdP (“known “TdP drugs”), as designated by the QT drugs list at www.crediblemeds.org. </p> <p><strong>Methods:</strong></p> <p>In aim 1, we used Medicare claims (2014-2016) and ICD-9/10 codes to identify patients taking the QT interval-prolonging drugs dofetilide or sotalol, which are used commonly in patients with HF and atrial fibrillation, as well as non-dofetilide or sotalol users among 3 groups: HFpEF, HFrEF, and no HF. Multinomial propensity score-matching was performed. Cochran–Mantel–Haenszel statistics and standardized differences were used to compare baseline characteristics. A generalized Cox proportional hazards model was used to estimate hazard ratios (HRs) and test the association of VT and SCA among dofetilide/sotalol users, HFpEF, HFrEF, and no HF.</p> <p>In Aim 2, the data source was electronic health records from the Indiana Network for Patient Care (February 2010 to May 2021). After removing patients with overlapping diagnoses of HFpEF and HFrEF, no diagnosis code, absence of QT interval records, and no validated record of using dofetilide or sotalol, we identified patients taking dofetilide or sotalol among three groups: HFrEF, HFpEF, and no HF. Cochran–Mantel–Haenszel statistics were used to compare baseline characteristics. QT interval prolongation was defined as heart rate-corrected QT (QTc) > 500 ms during dofetilide/sotalol therapy. Unadjusted odds ratios (OR) of QT interval prolongation were determined by univariate analysis, and adjusted ORs were determined by generalized estimating equations (GEE) with logit link to account for an individual cluster with different times of hospitalization and covariates.</p> <p>In aim 3, we used Medicare enrollment in fee-for-service medical and pharmacy benefits (2014 to 2016) and ICD-9/10 codes, we identified patients taking drugs known to cause torsades de pointes (TdP drugs; www.crediblemeds.org) and non-TdP drug users among three groups: HFrEF, HFpEF, and no HF. Multinomial propensity score-matching was performed to minimize baseline differences in covariates (patient demographics, comorbidities, health care utilization and drug history). Cochran–Mantel–Haenszel statistics and standardized differences were used to compare baseline characteristics. A generalized Cox proportional hazards model was used to estimate HRs and test the association of VT and SCA among TdP drug users with HFpEF, HFrEF, and no HF.</p> <p><strong>Results:</strong></p> <p>In Aim 1, VT and SCA occurred in 166 (10.68%) and 16 (1.03%), respectively, of 1,554 dofetilide/sotalol users with HFpEF, 543 (38.76%) and 40 (2.86%) of 1,401 dofetilide/sotalol users with HFrEF, and 245 (5.06%) and 13 (0.27%) of 4,839 dofetilide/sotalol users with no HF. The adjusted HR for VT in patients with HFrEF was 7.00 (95% CI 6.12-8.02) and in patients with HFpEF was 1.99 (1.71-2.32). The risk of VT associated with dofetilide/sotalol was increased across the overall study population (HR: 2.47 [1.89-3.23]). Use of dofetilide/sotalol increased the risk of VT in patients with HFrEF (HR: 1.53 [1.07-2.20]) and in those with HFpEF (HR: 2.34 [1.11-4.95]). However, while the overall risk of SCA was increased in patients with HFrEF (HR: 5.19 [4.10-6.57]) and HFpEF (HR: 2.53 [1.98-3.23]) compared to patients with no HF, dofetilide/sotalol use was not significantly associated with an increased risk of SCA.</p> <p>In Aim 2, QTc prolongation associated with dofetilide/sotalol occurred in 51.2% of patients with HFpEF, 70.1% of patients with HFrEF, and 29.4% of patients with no HF. After adjusting for age, sex, race, serum potassium and magnesium concentrations, kidney function, concomitant drug therapy, and comorbid conditions, the adjusted odds of having QTc interval larger than 500ms during the hospital stay were 5.23 [3.15-8.67] for HFrEF and 1.98 [1.17-3.33] for HFpEF with no HF as the reference group. </p> <p>In Aim 3, of 23,910 known TdP drug users with HFrEF, VT and SCA occurred in 4,263 (17.8%) and 493 (2.1%) patients, respectively. In comparison, among 31,359 known TdP drug users with HFpEF, VT and SCA occurred in 1,570 (5.0%) and 340 (1.1%) patients. VT and SCA occurred in 3,154 (0.8%) and 528 (0.1%) of 384,824 known TdP drug users without HF. The overall HR of both VT and SCA was increased in patients with HFrEF (HR: 7.18 [6.13-8.40])  and in those with HFpEF (HR: 2.09 [1.80-2.42]). The risk of VT associated with known TdP drugs was increased across the overall population (HR: 1.34 [1.20-1.51]). Use of known TdP drugs significantly increased the risk of VT and SCA in patients with HFrEF (HR: 1.34 [1.07-1.67]), but not in patients with HFpEF.</p> <p><strong>Conclusion:</strong></p> <p>HFpEF may exhibit an enhanced response to drug-associated VT, and is associated with a higher risk of drug-associated QTc interval prolongation. Further study is needed to identify methods to minimize this risk for patients with HFpEF requiring therapy with dofetilide, sotalol, or drugs known to cause TdP. </p>