Abstract Cardiovascular diseases are the leading cause of death in developed countries. Approximately 50% of these events are due to sudden cardiac death (SCD) and often without preceding diagnosis of cardiac disease. Many risk factors for cardiac events have been identified and prevention strategies have improved markedly. The aim of this thesis was to evaluate the usability of the 12-lead electrocardiogram (ECG) to predict cardiac events. The study population consisted of 10,904 middle-aged general population subjects with ECG recordings between the years 1966–1972 with a long follow-up (30±11 years). The first part of the thesis (I) focused on the prevalence and prognostic significance of fragmented QRS complex (fQRS). The prevalence of fQRS was 19.7%. Fragmented QRS complex did not predict mortality in subjects with no history of cardiac disease. Among subjects with underlying cardiac disease and lateral fQRS, the risk of cardiac death was 2.5-fold (P=0.001) and the risk of SCD was almost 3-fold (P=0.004). Other major electrocardiographic abnormalities were assessed in subjects without known cardiac disease for the risk of cardiac death, SCD and hospitalization due to coronary artery disease (II, III). Abnormal ECG was moderately associated with cardiac death after 10 and 30 years of follow-up (hazard ratio 1.7, P=0.009; hazard ratio 1.3, P>0.001, respectively) (II). The risk of hospitalization was not associated with abnormal ECG findings. Abnormal ECG moderately predicted SCD during 10 and 30 years of follow-up (hazard ratio 1.6, P=0.052; hazard ratio 1.3, P=0.007) (III). The risk of SCD was 3-fold when ≥2 ECG abnormalities were present. In conclusion, lateral fQRS in middle-aged subjects with underlying cardiac disease was associated with increased risk of death. Certain abnormal ECG findings associated with the risk of non-arrhythmic cardiac mortality and arrhythmic death. The risk of arrhythmic mortality was substantially elevated when multiple ECG abnormalities were present in middle-aged population. / Tiivistelmä Sydänsairaudet ovat yleisin kuolinsyy kehittyneissä maissa. Noin 50 % näistä kuolemista aiheutuu äkillisestä sydänpysähdyksestä, suuri osa ilman aiempaa tietoa sairaudesta. Useita sydänsairauksien riskitekijöitä on tunnistettu ja ennaltaehkäisy on kehittynyt merkittävästi. Väitöstutkimuksen tavoitteena on tutkia 12-kytkentäisen sydänsähkökäyrän (EKG) käyttökelpoisuutta sydänsairauksien ilmenemisen ennustamisessa. Tutkimusväestöön kuului 10,904 keski-ikäistä suomalaista henkilöä. Aineisto kerättiin vuosina 1966-1972 ja seuranta-aika oli 30 (±11) vuotta. Ensimmäisessä osajulkaisussa (I) tutkimme QRS-kompleksin fragmentaation vallitsevuutta ja sen vaikutusta ennusteeseen väestössä. Fragmentoituneen QRS-kompleksin esiintyvyys oli 19.7 %. Fragmentoitunut QRS-kompleksi ei lisännyt kuolemanriskiä henkilöillä, joilla ei ollut sydänsairautta. Henkilöillä, joilla oli todettu sydänsairaus, lateraalinen fQRS lisäsi sydänperäistä kuolleisuutta 2.5-kertaiseksi (P=0.001) ja rytmihäiriöperäistä kuolleisuutta 3-kertaiseksi (P=0.004). Tutkimme muiden poikkeavien EKG-löydösten ennustearvoa kuolleisuuteen ja sairaalahoidon tarpeeseen sepelvaltimokohtauksen vuoksi (II, III). Poikkeavien EKG-muutosten esiintymiseen liittyi lisääntyneen sydänperäisen kuoleman riski sekä 10 vuoden (riskitiheyssuhde 1.7, P=0.009) että 30 vuoden seurannassa (riskitiheyssuhde 1.3, P>0.001) (II). Poikkeavat EKG-muutokset eivät ennustaneet sairaalahoitojaksoja. Poikkeava EKG ennusti rytmihäiriöperäisen kuoleman riskiä sekä 10 vuoden (riskitiheyssuhde 1.6, P=0.052) että 30 vuoden seurannassa (riskitiheyssuhde 1.3, P=0.007) (III). Äkkikuoleman riski oli 3-kertainen henkilöillä, joilla todettiin ≥ 2 EKG-poikkeavuutta. Tutkimuksen yhteenvetona voidaan todeta, että fQRS lateraalisissa kytkennöissä lisäsi sydänperäisen kuoleman riskiä henkilöillä, joilla on todettu sydänsairaus. Tiettyihin poikkeaviin EKG-muutoksiin liittyi lisääntynyt ei-rytmihäiriöperäisen ja rytmihäiriöperäisen kuoleman riski. Useiden tutkittujen EKG-muutosten ilmentyminen samanaikaisesti lisäsi merkittävästi rytmihäiriöperäisen kuoleman riskiä keski-ikäisessä väestössä.

Hypertrophic cardiomyopathy is a heart disease that is characterized by an enlarged heart muscle. Mutations to sarcomere proteins in the muscle fibers give rise to the disease, and this review aims to compile the mechanisms by which the mutations cause the disease phenotype. β-myosin heavy chain mutants affect the thick filament structure and contraction velocity of the muscle. Mutations to the myosin-binding protein C produces truncated proteins with decreased expression in the cells. Troponin T mutants cause myofibrillar disarray, alters affinity to α-tropomyosin, and are linked to a higher risk of sudden death. Troponin I is an unpredictable mutant that needs to be further researched but is thought to cause regulatory problems. Mutations to α-tropomyosin and the regulatory myosin light chain both affect the Ca2+-affinity of the proteins and leads to contractile problems. Hypercontractility as a result of the mutations seems to be the primary cause of the disease. Hypertrophic cardiomyopathy is linked to sudden death, and factors such as a family history of sudden death, multiple simultaneous mutations, unexplained syncope, non-sustained ventricular tachycardia, abnormal blood pressure response and extreme hypertrophy (>30 mm) heightens the risk of a sudden death. An increased knowledge about the disease will aid in the mission to better the treatments for the affected, but further investigation of pathological pathways needs to be performed.

Профилактика внезапной сердечной смерти спорте является актуальной задачей, решение которой способно значительно улучшить показатели продолжительности и качества жизни спортсменов. Проблема состоит в отсутствии рекомендаций по планированию тренировочного процесса и профилактике возникновения угрожающих жизни состояний при занятиях спортом у лиц с синдромом дисплазии соединительно ткани. Цель исследования – повышение адаптивных возможностей организма и профилактику осложнений у молодых спортсменов с дисплазией соединительной ткани. В соответствии с целью была выдвинута гипотеза, что рациональное дозирование физических нагрузок в ходе тренировочного процесса, с учетом индивидуальных особенностей организма, у молодых спортсменов с синдромом дисплазии соединительной ткани позволит улучшить адаптацию к физическим нагрузкам, а также снизить риск развития осложнений дисплазии соединительной ткани, в том числе внезапной сердечной смерти. / Prevention of sudden cardiac death in sports is an urgent problem of the modern society. It is critically important to improve life expectancies and quality of life of competitive athletes. The main issue is the absence of recommendations for exercise prescription and training schedule in terms of connective tissue dysplasia syndrome. The purpose of the study was to increase the adaptation abilities of an organism and prevention of possible health complications in young athletes with connective tissue dysplasia. It was hypothesized that rational physical loads dozing in accordance to individual capacity of these individuals will result in better adaptation to exercise loads and decrease of the possible risks, including sudden cardiac death.

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>

Thesis (PhD)-- Stellenbosch University, 2014. / ENGLISH ABSTRACT: Ventricular arrhythmias are the most important cause of sudden cardiac death (SCD) among adults living in industrialised nations. Genetic factors have substantial effects in determining population-based risk for SCD and may also account for inter-individual variability in susceptibility. Great progress has been made in identifying genes underlying various Mendelian disorders associated with inherited arrhythmia susceptibility. The most well studied familial arrhythmia syndrome is the congenital long QT syndrome (LQTS) caused by mutations in genes encoding subunits of myocardial ion channels. Not all mutation carriers have equal risk for experiencing the clinical manifestations of disease (i.e. syncope, sudden death). This observation has raised the possibility that additional genetic factors may modify the risk of LQTS manifestations. This study establishes the genetic aetiology of LQTS in South Africa and Denmark through the identification and characterisation of LQTS-causative mutations in five previously identified genes, as well as examining possible novel genetic causes of LQTS in a cohort comprising Danish and British probands. We have functionally characterised several of the mutations identified in this study and examined other cardiac phenotypes that may be explained by variants causing repolarisation disorders. / AFRIKAANSE OPSOMMING: Ventrikulêre aritmie bly die enkele belangrikste oorsaak van skielike hart dood (SCD) onder volwassenes wat in geïndustrialiseerde lande woon. Genetiese faktore het aansienlike gevolge in die bepaling van bevolking-gebaseerde risiko vir SCD en kan ook verantwoordelik wees vir die inter-individuele variasie in vatbaarheid. Groot vordering is gemaak in die identifisering van gene onderliggende verskeie Mendeliese siektes wat verband hou met geërf aritmie vatbaarheid. Die mees goed bestudeerde familie aritmie sindroom is die aangebore lang QT-sindroom (LQTS) wat veroorsaak word deur mutasies in gene kode subeenhede van miokardiale ioonkanale. Nie alle mutasie draers het 'n gelyke risiko vir die ervaring van die kliniese manifestasies van die siekte (dws sinkopee, skielike dood). Hierdie waarneming het die moontlikheid genoem dat genetiese faktore anders as die primêre siekte-verwante mutasie kan die risiko van LQTS manifestasies verander. Hierdie studie stel die genetiese oorsake van LQTS in Suid-Afrika en Denemarke deur die identifisering en karakterisering van LQTS-veroorsakende mutasies in vyf voorheen geïdentifiseer gene, asook die behandeling van moontlike nuwe genetiese oorsake van LQTS in 'n groep wat bestaan uit van die Deense en die Britse probands. Ons het funksioneel gekenmerk verskeie van die mutasies wat in hierdie studie ondersoek en ander kardiovaskulêre fenotipes wat deur variante veroorsaak repolarisasie versteurings verduidelik word. / South African National Research Foundation / Harry and Doris Crossley Foundation / Danish Strategic Research Foundation.

Vinte e seis pacientes com cardiomiopatia hipertrófica e fatores de risco de morte súbita, foram submetidos a implante de cardioversor-desfibrilador implantável de dupla-câmara, com seguimento médio de 19 meses. Observou-se quatro choques em arritmias letais, 4 pacientes apresentaram TVNS e 5 taquiarritmias supraventriculares. Ocorreu um óbito.Conclusões: Observamos: TPSV em 19,2%; TVNS em 15,4% e TVS/FV em 15,4%. Nenhuma variável clínica ou demográfica, discriminou o comportamento clínico ou funcional pós-implante de CDI; a recorrência de síncope pós implante de CDI, não se associou à presença de eventos arrítmicos e a hipertrofia maior que 30 mm se associou à choque precoce do CDI (p=0,003). / During 19 months of average follow-up period, we followed 26 patients with hypertrophic cardiomyopathy and high risk for sudden death, all treated by dual chamber implantable cardioverter-defibrillator. 4 patients had received appropriate ICD discharge, 4 patients with NSVT and 5 supraventricular arrhythmias. One death had occurred. Conclusions: we observed: supraventricular arrhythmias in 19,2%; NSVT in 15,4% and VT/VF in 15,4%. The clinical or demographic outcomes did not suggest any clinical or functional results after ICD implantation; syncope may occur after ICD implantation and no arrhythmias recordered by intracardiac electrograms and left-ventricular-wall thickness greater than 30 mm is associated with early ICD shocks (p=0,003).

Le diabète de type 2 (DT2) est devenu de plus en plus une maladie métabolique chronique fréquente, associée à de nombreuses complications micro et macro-vasculaires. Les patients diabétiques ont environ deux fois plus de risque de mort subite d'origine cardiaque (MSC) que ceux normaux. Les interventions pharmacologiques (anti-plaquettaires, anti-hypertenseurs, anti-diabétiques et hypolépimiants) nous semblent les candidats les plus efficaces, accessibles et économiques pour prévenir cet événement à long terme, par contre leurs effets sur la MSC n'ont pas été bien connus. Nous visons à estimer leur impact sur la santé publique et à optimiser leur utilisation chez les DT2, grâce à des études d'analyse, de synthèse et de modélisation.Ce travail inclut trois étapes: premièrement, de construire un score de risque permettant de prédire le risque de MSC dans le DT2 en utilisant les bases de données INDANA. Deuxièmement, d'effectuer des méta-analyses/revues systématiques de différentes stratégies thérapeutiques afin d'estimer leurs effets sur le risque de MSC. Enfin, de simuler différentes stratégies sur une population virtuelle réaliste (PVR) des diabétiques français et d'intégrés les résultats obtenus sur cette plate-forme pour estimer le risque de MSC avec et sans traitements. Cette simulation permet d'estimer leurs bénéfices absolus, par le nombre d'événements prévus (Number of Events Prevented, NEP) et le nombre de patients à traiter pour prévenir une MSC (Number Needed to Treat, NNT). Nous avons construit un score incluant 7 facteurs de risque de MSC chez les patients atteints d'hypertension artérielle (+/- diabète) et collecté les meilleures estimations sur l'effet des médicaments. Notre simulation sur la PVR générée a suggéré que chez 10% des patients ayant le risque de MSC prédit le plus haut, la co-prescription de l'inhibiteurs de l'enzyme de conversion-l'aspirine-l'empagliflozine permettait de prévenir une MSC sur 57 individus traités dans les 5 ans. Le chiffre correspondant pour toute la PVR était 135. Nous concluons que cette approche pourrait aider à mieux transposer les résultats des essais cliniques à la pratique ; et à faciliter la décision clinique aux niveaux populationnel et individuel / Type 2 diabetes (T2D) has increasingly become a common metabolic condition, associated with numerous micro and macro-vascular complications. Diabetic patients are at about two-time higher risk of sudden cardiac death (SCD), compared to non-diabetic ones. Pharmacologic intervention (anti-platelet, anti-hypertensive, lipid lowering, and to a lesser extent, anti-diabetic agents) appear to be the most efficient and economic candidate to prevent this event at long term, yet treatment effects have not well addressed. We aimed to optimize their use and estimate their impact on public health via analysis, synthesis and modeling studies.This work engaged three phases: First, to construct a risk score to predict SCD risk in T2D from the INDANA database. Second, to perform the meta-analyses/systematic reviews of different therapeutic strategies in order to estimate their effects on SCD risk. Finally, to simulate therapeutic strategies on a generated French diabetic realistic virtual population (RVP) of T2D, by estimating the occurrence of SCD with and without treatments, thus their absolute benefits, through the Number of Events Prevented (NEP) due to treatment, and the Number of patients Needed to be Treated to prevent one SCD (NNT).We built a 7-risk factor to predict 5-year risk of SCD in patients with hypertension (+/-diabetes) and collected the best evidence on drugs’ effects. Integrating and simulating altogether on a generated French diabetic RVP suggested that for every 57 individuals of the 10% highest predicted SCD risk, the co-prescription of angiotensin converting enzyme inhibitor-aspirin-empagliflozin could prevent one SCD in 5 years. For the whole population, the corresponding number was 135. In perspectives, this approach could help better transposing clinical trial results into practice and facilitating clinical decision at both public health and individual levels

The aim was to investigate associations of fitness and types and levels of physical activity with subsequent risk of cardiovascular disease. Four large-scale longitudinal cohort studies were used. The exposures were different measures related to physical activity and the outcomes were obtained through linkage to the Swedish In-Patient Register. In a cohort of 466 elderly men without pre-existing cardiovascular disease, we found that skeletal muscle morphology was associated with risk of cardiovascular events. A high amount of type I (slow-twitch, oxidative) skeletal muscle fibres was associated with lower risk of cardiovascular events and high amount of type IIx was associated with higher risk of cardiovascular events. This association was only seen among physically active men. Among 39,805 participants in a fundraising event, higher levels of both total and leisure time physical activity were associated with lower risk of heart failure. The associations were strongest for leisure time physical activity. In a cohort of 53,755 participants in the 90 km skiing event Vasaloppet, a higher number of completed races was associated with higher risk of atrial fibrillation and a higher risk of bradyarrhythmias. Further, better relative performance was associated with a higher risk of bradyarrhythmias. Among 1,26 million Swedish 18-year-old men, exercise capacity and muscle strength were independently associated with lower risk of vascular disease. The associations were seen across a range of major vascular disease events (ischemic heart disease, heart failure, stroke and cardiovascular death). Further, high exercise capacity was associated with higher risk of atrial fibrillation and a U-shaped association with bradyarrhythmias was found. Higher muscle strength was associated with lower risk of bradyarrhythmias and lower risk of ventricular arrhythmias. These findings suggest a higher rate of atrial fibrillation with higher levels of physical activity. The higher risk of atrial fibrillation does not appear to lead to a higher risk of stroke. In contrast, we found a strong inverse association of higher exercise capacity and muscle strength with vascular disease. Further, high exercise capacity and muscle strength are related to lower risk of cardiovascular death, including arrhythmia deaths. From a population perspective, the total impact of physical activity on cardiovascular disease is positive.

No description available.