EKG registrerar hjärtats elektriska aktivitet genom att registrera spänningsskillnaden mellan olika specifika punkter på kroppsytan. QT-tiden mäts från början av QRS-komplexet till T-vågens slut. QT-tiden visar hur länge den elektriska impulsen som ger en hjärtmuskelkontraktion i hjärtats kamrar varar. En förlängd QT-tid kan uppstå vid bland annat mutationer i gener som kodar för hjärtats jonkanaler. Normalt ska QT-durationen förkortas med högre hjärtfrekvens men vid långt QT-syndrom förkortas inte QT-duration som normalt med ökande hjärtfrekvens. Förlängd QT-tid medför ökad risk för plötslig död. Symptomen vid lång QT-tid är yrsel, hjärtklappning och svimning. Syftet med studien var att validera en ny utvärderingsmetod mot en befintlig metod av QT-mätning under arbete. Den befintliga metoden genomfördes med papper, penna och linjal, medan den nya metoden genomfördes digitalt på en mjukvara, EC-view. Totalt samlades 37 patientdata med misstänkt förlängd QT-mätning in. Ytterligare 10 patientdata från rutin arbets-EKG med andra kliniska frågeställning insamlades med informerat samtycke från patienter. Resultatet erhållen av Pearsons rangkorrelation visar att korrelationen mellan metoderna är 0,90, vilket tyder på en stark korrelation. Bland-Altman analys visar ett p-värde på <0,001 som tyder på att det inte finns någon statistiskt signifikant skillnad i medelvärde mellan QT-mätningarna med digital metod respektive manuell metod på gruppnivå. Några mätningar har avvikit på patientnivå under arbete eller under återhämtningen. Slutsatsen är att metoderna korrelerar på gruppnivå. / ECG registers the heart's electrical activity by registering the voltage difference between specific different points on the body’s surface. The QT-interval measures from the start of QRS-complex to the end of the T-waves. The QT-interval corresponds to the electrical impulse that causes myocardial contraction in the heart’s chambers. An extended QT-time may develop due to mutations in genes that codes for ion channels in the heart. Normally the QT-duration is decreased with a higher heart-rate but in long QT-syndrome the QT-interval does not decrease with the increase in heart rate. Long QT-syndrome increases the risk for sudden death. The symptoms in long QT-syndrome includes dizziness, palpitation and fainting. The aim of the study was to validate a new evaluation method against an existing method of QT-measurements during exercise. The existing method was performed with paper, pencil and ruler, whilst the newer method was performed digitally on a software, EC-view. In total 37 patient data with suspected long QT-syndrome were collected. An additional 10 patient data sets from routine clinical exercise stress tests with other clinical hypothesis were gathered with a written consent obtained the patients. The results obtained by Pearson’s rang correlation shows that the correlation between the methods are 0,90, indicating a strong correlation. Bland-Altman analysis shows a P-value on less than 0,001 which means that there was no statistically significant difference in the average between QT-measurements with digital method respective manual method at group level. Some of the measurements have deviated at the patient level during exercise stress test or after the stress test. The conclusion is that the methods correlate on a group level.

京都大学 / 新制・課程博士 / 博士(医学) / 甲第24485号 / 医博第4927号 / 新制||医||1063(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 江藤 浩之, 教授 湊谷 謙司, 教授 大鶴 繁 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DGAM

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<p>Metadon je sintetski agonist opijatnih receptora koji se primenjuje u sklopu supstitucione terapije opijatnih zavisnika metadonom (STM) i u terapiji hroničnog bola. Dugoročna primena STM je praćena blagim, uglavnom prolaznim, neželjenim delovanjima. Međutim, metadon pripada grupi lekova koji mogu da prouzrokuju prolongaciju korigovanog QT intervala (QTc) u elektrokardiogramu (EKG-u) i povećaju rizik za nastanak potencijalno fatalnih aritmija tipa torsades de pointes. Opijatni zavisnici metadon najče&scaron;će koriste u kombinaciji sa benzodiazepinima, i ova kombinacija lekova predstavlja faktor rizika za nastanak smrtnog ishoda. Iako je najveći broj lekara upoznat sa rizikom za razvoj respiratorne depresije prilikom primene opijata u kombinacji sa benzodiazepinima, velika studija otkriva da su ventrikularne aritmije i srčani zastoj najče&scaron;će prijavljivana neželjena delovanja metadona, primenjenog u kombinaciji sa benzodiazepinima. Ciljevi ovoga radu su da se analizom smrtnih slučajeva povezanih sa upotrebom metadona (MRDs) tokom desetogodi&scaron;njeg perioda na teritoriji Vojvodine i sprovođenjem kliničkog ispitivanja kod opijatnih zavisnika na STM proceni kardiolo&scaron;ka bezbednost primene metadona, posebno u kombinaciji sa benzodiazepinima. Sprovedena je retrospektivna studija za određivanje karakteristika MRDs na teritoriji Vojvodine, kao i kliničko ispitivanje u kome su učestvovali opijatni zavisnici koji počinju sa STM. Snimanje EKG-a (za izračunavanje QTc intervala) i uzorkovanje krvi (za određivanje koncentracije metadona i diazepama i vrednosti troponina) je sprovedeno kod svih učesnika istraživanja u 5 vremenskih tačaka (pre početka primene STM, 8. i 15. dana i nakon 1. i 6. meseca primene STM). Koncentracije metadona i diazepama u serumu su određivane metodom tečne hromatografije sa masenom spektrometrijom (LC-MS). U Vojvodini je zapažena rastuća tendencija MRDs, ali ni jedan od umrlih nije bio na STM, i najverovatnije su samoinicijativno koristili metadon i benzodiazepine. Patohistolo&scaron;ki nalaz na srcu može govoriti u prilog kardiotoksičnosti metadona i njegove kombinacije sa benzodiazepinima, pogotovo kod slučajeva sa pronađenim akutnim miokardijalnim o&scaron;tećenjem. &Scaron;to se tiče hroničnih promena na srcu, ne postoji mogućnosti da se potvrdi niti opovrgne uloga psihostimulanasa. Detektovane koncentracije metadona i diazepama kod MRDs su bile u opsegu terapijskih (&lt;1 &mu;g/ml). Poredeći socio-demografske karakteristike opijatnih zavisnika koji su počeli sa STM u ovom istraživanju sa podacima iz sličnih studija sprovedenih &scaron;irom sveta, zapažena je sličnost u pogledu velikog broja karakteristika. Srednje doze metadona 8., 15. dana i nakon 1. i 6. meseca primene STM su bile 40,23&plusmn;17,11 mg, 47,11&plusmn;16,79 mg, 50,00&plusmn;17,55 mg i 78,63&plusmn;18,14 mg, dok su srednje doze diazepama u istim vremenskim tačkama bile 35,92&plusmn;10,47 mg, 33,89&plusmn;9,23 mg, 28,33&plusmn;11,55 mg i 28,12&plusmn;11,67 mg. Srednje koncentracije metadona su u posmatranim tačkama ispitivanja iznosile 153,44&plusmn;111,51 ng/ml, 157,43&plusmn;112,39 ng/ml, 176,77&plusmn;118,56 ng/ml i 342,86&plusmn;181,54 ng/ml, dok su srednje koncentracije diazepama bile 923,00&plusmn;537,89 ng/ml, 923,76&plusmn;739,96 ng/ml, 560,74&plusmn;436,72 ng/ml i 1045,32&plusmn;932,72 ng/ml. Dužina QTc intervala pre primene STM je bila 411,87&plusmn;27,22 ms, tj. 414,64&plusmn;29,38 ms 8. dana STM, 416,97&plusmn;26,39 15. dana, i 425,20&plusmn;17,71 ms nakon 1. meseca tj. 423,50&plusmn;14,72 ms nakon 6. meseca primene STM. Pokazan je statistički značajan porast dužine QTc intervala nakon 1. i nakon 6. meseca primene STM u odnosu na vrednost pre primene STM, kako u grupi svih ispitanika, tako i u podgrupi mu&scaron;kog pola. Pokazano je postojanje statistički značajne korelacije između koncentracije metadona i dužine QTc intervala nakon 15. dana, 1. i 6. meseca primene STM, kako kod svih ispitanika, tako i u podgrupi mu&scaron;kog pola. Ova korelacija ostaje statistički značajna i ukoliko se uključe i drugi faktori &ndash; koncentracija diazepama i dužina perioda upotrebe heroina, kod svih ispitanika i u podgrupi mu&scaron;kog pola nakon 15 dana i mesec dana primene STM, kao i u podgrupi mu&scaron;kog pola nakon 6. meseca STM. Iako nijedan pacijent nije prijavio neko neželjeno delovanje metadona na nivou kardiovaskularnog sistema, najveći broj pacijenata oba pola se nakon prvog meseca primene STM žalio na pojačano znojenje i opstipaciju. Koncentracije metadona i diazepama u uzorcima krvi kod MRDs se nalaze u rasponu koncentracija ovih lekova u krvi ispitanika koji su učestvovali u prospektivnoj studiji. Trećina umrlih je imala samo znake akutnog o&scaron;tećenja srca, dok do porasta troponina i vrednosti QTc intervala preko 500 ms nije do&scaron;lo ni kod jednog ispitanika iz prospektivne studije. Potrebno je sprovesti dalja istraživanja sa ciljem razja&scaron;njenja moguće uloge benzodiazepina u povećanju kardiotoksičnosti metadona kod opijatnih zavisnika na STM.</p> / <p>Methadone is a synthetic agonist of opioid receptors which is used in methadone maintenance tratment (MMT) of opiate addicts as well as in the treatment of chronic pain. A long-term use of MMT is followed by mild, mostly transient, adverse effects. However, methadone belongs to a group of medicines which can provoke a prolongation of QTc (corrected QT) interval in electrocardiogram (ECG) and thus increase the risk from the development of potentially fatal arrhythmias &ndash; torsades de pointes. Moreover, methadone is widely associated with benzodiazepines use in heroin addicts, and this combination is considered as a risk factor for lethal outcome. Despite the fact that most of health care professionals are aware of possible respiratory depressant effect of methadone and benzodiazepines co-administration, recently published data reveal that ventricular arrhythmia and cardiac arrest are currently the most frequent adverse event attributed to methadone and benzodiazepine co-medication. The aim of this study is to assess cardiac safety of methadone use, especially in combination with benzodiazepines, by analyzing characteristics of methadone-related deaths (MRDs) during 10-year period as well as by conducting a clinical trial among opiate addicts in MMT. A retrospective study to determine the characteristics of MRDs in Vojvodina, as well as a clinical trial in which participated opiate addicts at the start of MMT were performed. ECG (to calculate QTc interval) and blood sampling (to determine methadone and diazepam concentrations and troponin values) were performed in all study participants at five time points (before the introduction of MMT, on 8th, on 15th day, after 1 and 6 months of MMT). Methadone and diazepam concentrations in serum were determined by using liquid chromatography-mass spectrometry (LC-MS). An increasing tendency of MRDs was observed in the region of Vojvodina, but none of the victims were under healthcare professionals&rsquo; control, and, most commonly, they used methadone and benzodiazepines, on their own initiative. Pathohistological findings in the heart in MRDs might support cardiac adverse effects of methadone and its combination with benzodiazepines, especially in cases with acute myocardial damage. As for the chronic heart changes, we can neither confirm nor exclude the role of psychostimulants. Detected concentrations of methadone and diazepam were in therapeutic range (&lt;1 &mu;g/ml). Comparing socio-demographic characteristics of opiate addicts who started with MMT in this study with data from similar studies conducted worldwide, the similarity in terms of large number of features was observed. The mean methadone dose on the 8th, 15th days, and after 1 and 6 months of MMT was 40.23&plusmn;17.11 mg, 47.11&plusmn;16.79 mg, 50.00&plusmn;17.55 mg and 78.63&plusmn;18.14 mg, respectively, while the mean diazepam dose at the same time points was 35.92&plusmn;10.47 mg, 33.89&plusmn;9.23 mg, 28.33&plusmn;11.55 mg and 28.12&plusmn;11.67 mg, respectively. The mean methadone concentration at observed time points was 153.44&plusmn;111.51 ng/ml, 157.43&plusmn;112.39 ng/ml, 176.77&plusmn;118.56 ng/ml and 342.86&plusmn;181.54 ng/ml, respectively, while the mean diazepam concentration was 923.00&plusmn;537.89 ng/ml, 923.76&plusmn;739.96 ng/ml, 560.74&plusmn;436.72 ng/ml and 1045.32&plusmn;932.72 ng/ml, respectively. The length of QTc interval before the introduction of MMT was 411.87&plusmn;27.22 ms, 414.64&plusmn;29.38 ms on the 8th day of MMT, 416.97&plusmn;26.39 on the 15th day of MMT, after 1 month of MMT 425.20&plusmn;17.71 ms and after 6 months of MMT 423.50&plusmn;14.72 ms. There was a statistically significant increase in the length of QTc interval after 1 and 6 months of MMT in comparison to the value before the application of MMT, within the whole group of patients and in the subgroup of men. A statistically significant correlation between the concentration of methadone and QTc interval length after 15 days, 1 and 6 months of MMT, both in the whole group and in the subroup of men was observed. The correlation remained statistically significant if the other factors, such as concentration of diazepam and the length of heroin use, were included, in all patients and in the subgroup of men after 15 days and one month of MMT as well as in the subgroup of men after 6 months of MMT. Although none of the patients reported any cardiac adverse effect of methadone, the majority of them complained of sweating and constipation after the first month of MMT. Concentrations of methadone and diazepam in blood samples in MRDs were within the range of concentrations of these drugs in blood of patients who participated in the prospective study. In one third of MRDs only signs of acute myocardial damage were detected, while an increase in troponin values and the length of QTc interval over 500 ms did not occur in any patient in the prospective study. Further studies could clarify the possible role of benzodiazepines in the increasing cardiotoxicity of methadone in opiate addicts in MMT.</p>

Background: We aimed to increase the knowledge regarding the familial arrhythmogenic disorder Long QT Syndrome (LQTS) and its recessive variant Jervell and Lange-Nielsen Syndrome (JLNS) in Sweden, including prevalences and clinical phenotypes. A specific focus was directed towards two KCNQ1 mutations –p.Y111C and p.R518X- commonly identified in Swedish LQTS index cases. Methods: Cases and families with LQTS (p.Y111C or p.R518X) and JLNS were recruited via regional clinical practices, national referrals to the Clinical Genetics laboratory, Umeå University Hospital, and a national inventory. Molecular genetics methods were used for case ascertainment. Clinical data was obtained via medical records, a questionnaire, and/or an interview. Electrocardiograms were manually assessed. In p.R518X heterozygotes intra-familial phenotypic variability (QTc and cardiac events) was assessed by analysis of sequence variants (modifier genes). The origins of the mutations p.Y111C and p.R518X were investigated using genealogical and haplotype analysis (microsatellite markers). In families sharing a common haplotype mutation age and associated prevalence was analyzed using ESTIAGE and DMLE computer software. Results: We identified p.Y111C (170 mutation-carriers) and p.R518X (101 mutation-carriers) as two major causes of LQTS/JLNS in Sweden. LQTS phenotype was revealed to be relatively benign in p.Y111C and p.R518X (annual incidence of life-threatening cardiac events, before therapy 0.05% and 0.04%, respectively). Gender-specific effects of genetic modifiers on phenotypic expression were seen. A founder origin, approximately 600-700 years ago in two northern river valleys was established for p.Y111C and p.R518X, and a high prevalence of LQTS founder descendants suggested. A minimum JLNS prevalence of 1:200 000 in preadolescent Swedish children was revealed. JLNS phenotype was mainly severe, with a cumulative incidence of life-threatening cardiac events of 53% (annual incidence rate before therapy 5%) and four sudden deaths. Possible founder effects regarding four KCNQ1 mutations; p.Y111C (8%), p.R518X (50%), c.572_576del (17%) and p.Q530X (8%) together explained 83% of the JLNS mutation-spectrum in Sweden, consisting of 8 KCNQ1 mutations. Conclusion: The high prevalence of p.Y111C- and p.R518X-related LQTS as well as JLNS revealed in Sweden could be explained by the combination of mild clinical phenotypes in heterozygotes and strong founder effects present during the population development of northern Sweden. Increased knowledge regarding the occurrence of LQTS and JLNS as well as mutation- and/or genotype-specific data constitute prerequisites for possible improvement of patient management.

Les médicaments qui provoquent un allongement de la repolarisation cardiaque, mesuré sur l’électrocardiogramme (ECG) par la prolongation de l’intervalle QT, ont été associés à une augmentation du risque pro-arythmique, et plus particulièrement à la survenue de Torsades de pointes, une tachycardie ventriculaire polymorphe potentiellement mortelle. Les méthodes d'analyse du QT conventionnelles se restreignent à l’extraction de quelques complexes ECG. Cette pratique se traduit par de nombreuses limitations. L’inclusion de tous les battements enregistrés sur 24h et mesurés par des méthodes automatiques de mesure ECG a le potentiel de résoudre ces inconvénients. Ce travail de thèse a démontré que les méthodes de mesure ECG automatisées et les analyses continues peuvent supplanter les méthodes conventionnelles pour l'analyse de la prolongation du QT lors des essais cliniques. Des recommandations ont été établis afin de permettre une utilisation optimale des méthodes d'analyse ECG continues. / Drugs which induce a delay in cardiac repolarization measured as QT interval prolongation on the electrocardiogram (ECG) have been associated with a potential to increase the risk of arrhythmias, especially Torsades de pointes (TdP), a potentially lethal polymorphic ventricular tachycardia. The analyses performed using conventional methods are restricted to the extraction of a few ECG complexes. This practice is associated with several limitations. In contrast, the inclusion of all beats measured by computerized methods from continuous 24 h recordings could resolve all of these deficiencies. The current work demonstrated that automated ECG measurement methods employing continuous analysis can supplant conventional methods for the evaluation of QT prolongation in clinical studies. Recommendations have been established to provide an optimal use of continuous ECG analysis.

[ES] Las enfermedades cardiovasculares siguen siendo la principal causa de muerte en Europa. Las arritmias cardíacas son una causa importante de muerte súbita, pero sus mecanismos son complejos. Esto denota la importancia de su estudio y prevención. La investigación sobre electrofisiología cardíaca ha demostrado que las anomalías eléctricas causadas por mutaciones que afectan a canales cardíacos pueden desencadenar arritmias. Sorprendentemente, se ha descubierto una gran variedad de fármacos proarrítmicos, incluidos aquellos que usamos para prevenirlas. Las indicaciones de uso de fármacos actuales intentaron solucionar este problema diseñando una prueba para identificar aquellos fármacos que podían ser peligrosos basado en el bloqueo de un solo canal iónico. El estudio de las interacciones fármaco-canal ha revelado la existencia no sólo de compuestos que bloquean múltiples canales, sino también una gran complejidad en esas interacciones. Esto podría explicar por qué algunos medicamentos pueden mostrar efectos muy diferentes en la misma enfermedad. Existen dos desafíos importantes con respecto a los efectos de los fármacos en la electrofisiología cardíaca. Por un lado, las empresas y entidades reguladoras están buscando una herramienta de alto rendimiento que mejore la detección del potencial proarrítmico durante el desarrollo de fármacos. Por otro lado, los pacientes con anomalías eléctricas a menudo requieren tratamientos personalizados más seguros. Las simulaciones computacionales contienen un poder sin precedentes para abordar fenómenos biofísicos complejos. Deberían ser de utilidad a la hora de determinar las características que definen tanto los efectos beneficiosos como no deseados de los fármacos mediante la reproducción de datos experimentales y clínicos. En esta tesis doctoral, se han utilizado modelos computacionales y simulaciones para dar respuesta a estos dos desafíos. El estudio de los efectos de los fármacos sobre la actividad cardíaca se dividió en el estudio de su seguridad y de su eficacia, respectivamente. Para dar respuesta al primer desafío, se adoptó un enfoque más amplio y se generó un nuevo biomarcador fácil de usar para la clasificación del potencial proarrítmico de los fármacos utilizando modelos del potencial de acción de células y tejidos cardíacos humanos. Se integró el bloqueo de múltiples canales a través de IC50 y el uso de concentraciones terapéuticas con el fin de mejorar el poder predictivo. Luego, se entrenó el biomarcador cuantificando el potencial proarrítmico de 84 fármacos. Los resultados obtenidos sugieren que el biomarcador podría usarse para probar el potencial proarrítmico de nuevos fármacos. Respecto al segundo desafío, se adoptó un enfoque más específico y se buscó mejorar la terapia de pacientes con anomalías eléctricas cardíacas. Por lo tanto, se creó un modelo detallado de la mutación V411M del canal de sodio, causante del síndrome de QT largo, reproduciendo datos clínicos y experimentales. Se evaluaron los posibles efectos beneficiosos de ranolazina, a la par que se aportó información sobre los mecanismos que impulsan la efectividad de la flecainida. Los resultados obtenidos sugieren que, si bien ambos fármacos mostraron diferentes mecanismos de bloqueo de los canales de sodio, un tratamiento con ranolazina podría ser beneficioso en estos pacientes. / [CA] Les malalties cardiovasculars continuen sent la principal causa de mort a Europa. Les arrítmies cardíaques són una causa important de mort sobtada, però els seus mecanismes són complexos. Això denota la importància del seu estudi i prevenció. La investigació sobre electrofisiologia cardíaca ha demostrat que les anomalies elèctriques que afecten a canals cardiacs poden desencadenar arrítmies. Sorprenentment, s'ha descobert una gran varietat de fàrmacs proarrítmics, inclosos aquells que utilitzem per a previndre-les. Les indicacions d'ús de fàrmacs actuals van intentar solucionar aquest problema dissenyant una prova per a identificar aquells fàrmacs que podien ser perillosos basada en el bloqueig d'un sol canal iònic. L'estudi de les interaccions fàrmac-canal ha revelat l'existència no sols de compostos que bloquegen múltiples canals, sinó també una gran complexitat en aquestes interaccions. Això podria explicar per què alguns medicaments poden mostrar efectes molt diferents en la mateixa malaltia. Existeixen dos desafiaments importants respecte als efectes dels fàrmacs en la electrofisiologia cardíaca. D'una banda, les empreses i entitats reguladores estan buscant una eina d'alt rendiment que millore la detecció del potencial proarrítmic durant el desenvolupament de fàrmacs. D'altra banda, els pacients amb anomalies elèctriques sovint requereixen tractaments personalitzats més segurs. Les simulacions computacionals contenen un poder sense precedents per a abordar fenòmens biofísics complexos. Haurien de ser d'utilitat a l'hora de determinar les característiques que defineixen tant els efectes beneficiosos com no desitjats dels fàrmacs mitjançant la reproducció de dades experimentals i clíniques. En aquesta tesi doctoral, s'han utilitzat models computacionals i simulacions per a donar resposta a aquests dos desafiaments. L'estudi dels efectes dels fàrmacs sobre l'activitat cardíaca es va dividir en l'estudi de la seva seguretat i la seva eficacia. Per a donar resposta al primer desafiament, es va adoptar un enfocament més ampli i es va generar un nou biomarcador fàcil d'usar per a la classificació del potencial proarrítmic dels fàrmacs utilitzant models del potencial d'acció de cèl·lules i teixits cardíacs humans. Es va integrar el bloqueig de múltiples canals a través d'IC50 i l'ús de concentracions terapèutiques amb la finalitat de millorar el poder predictiu. Després, es va entrenar el biomarcador quantificant el potencial proarrítmic de 84 fàrmacs. Els resultats obtinguts suggereixen que el biomarcador podria usar-se per a provar el potencial proarrítmic de nous fàrmacs. Respecte al segon desafiament, es va adoptar un enfocament més específic i es va buscar millorar la teràpia de pacients amb anomalies elèctriques cardíaques. Per tant, es va crear un model detallat de la mutació V411M del canal de sodi, causant de la síndrome de QT llarg, reproduint dades clíniques i experimentals. Es van avaluar els possibles efectes beneficiosos de ranolazina, a l'una que es va aportar informació sobre els mecanismes que impulsen l'efectivitat de la flecainida. Els resultats obtinguts suggereixen que, si bé tots dos fàrmacs van mostrar diferents mecanismes de bloqueig dels canals de sodi, un tractament amb ranolazina podria ser beneficiós en aquests pacients. / [EN] Cardiovascular disease remains the main cause of death in Europe. Cardiac arrhythmias are an important cause of sudden death, but their mechanisms are complex. This denotes the importance of their study and prevention. Research on cardiac electrophysiology has shown that electrical abnormalities caused by mutations in cardiac channels can trigger arrhythmias. Surprisingly, a wide variety of drugs have also shown proarrhythmic potential, including those that we use to prevent arrhythmia. Current guidelines designed a test to identify dangerous drugs by assessing their blocking power on a single ion channel to address this situation. Study of drug-channel interactions has revealed not only compounds that block multiple channels but also a great complexity in those interactions. This could explain why similar drugs can show vastly different effects in some diseases. There are two important challenges regarding the effects of drugs on cardiac electrophysiology. On the one hand, companies and regulators are in search of a high throughput tool that improves proarrhythmic potential detection during drug development. On the other hand, patients with electrical abnormalities often require safer personalized treatments owing to their condition. Computer simulations provide an unprecedented power to tackle complex biophysical phenomena. They should prove useful determining the characteristics that define the drugs' beneficial and unwanted effects by reproducing experimental and clinical observations. In this PhD thesis, we used computational models and simulations to address the two abovementioned challenges. We split the study of drug effects on the cardiac activity into the study of their safety and efficacy, respectively. For the former, we took a wider approach and generated a new easy-to-use biomarker for proarrhythmic potential classification using cardiac cell and tissue human action potential models. We integrated multiple channel block through IC50s and therapeutic concentrations to improve its predictive power. Then, we quantified the proarrhythmic potential of 84 drugs to train the biomarker. Our results suggest that it could be used to test the proarrhythmic potential of new drugs. For the second challenge, we took a more specific approach and sought to improve the therapy of patients with cardiac electrical abnormalities. Therefore, we created a detailed model for the long QT syndrome-causing V411M mutation of the sodium channel reproducing clinical and experimental data. We tested the potential benefits of ranolazine, while giving insights into the mechanisms that drive flecainide's effectiveness. Our results suggest that while both drugs showed different mechanisms of sodium channel block, ranolazine could prove beneficial in these patients. / This PhD thesis was developed within the following projects: Ministerio de Economía y Competitividad and Fondo Europeo de Desarrollo Regional (FEDER) DPI2015-69125-R (MINECO/FEDER, UE): Simulación computacional para la predicción personalizada de los efectos de los fármacos sobre la actividad cardiaca. Dirección General de Política Científica de la Generalitat Valenciana (PROMETEU2016/088): “Modelos computacionales personalizados multiescala para la optimización del diagnóstico y tratamiento de arritmias cardiacas (personalised digital heart). Vicerrectorado de Investigación, Innovación y Transferencia de la Universitat Politècnica de València, Ayuda a Primeros Proyectos de Investigación (PAID-06-18), and by Memorial Nacho Barberá. Instituto de Salud Carlos III (La Fe Biobank PT17/0015/0043). / Cano García, J. (2021). Prediction of the effects of drugs on cardiac activity using computer simulations [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/164094

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