Abstract Sudden cardiac death (SCD) is a major medical and public health concern responsible for 50% of cardiovascular deaths and as much as 15% to 20% of overall mortality. Coronary heart disease is the underlying cause of most of these deaths, and in 50% of such cases, SCD is the first manifestation of the disease. Researchers have investigated numerous noninvasive methods to more accurately identify individuals at high risk of SCD, but most such studies have focused on patients with specific heart disease. The standard 12-lead electrocardiogram (ECG) is a widely available tool to analyze the electrical activity of the heart, but few epidemiological studies have successfully identified specific electrocardiographic risk markers of SCD at the population level. This thesis aims to clarify the prognostic implications of several ECG patterns in the general population. We evaluated the 12-lead ECGs of 10899 middle-aged Finnish subjects (52% male) recorded between 1966 and 1972, and followed the subjects for 30 ±  11 years. The prevalence of a prolonged QRS duration ≥ 110 ms and nonspecific intraventricular conduction delay (IVCD; defined as QRS ≥ 110 ms with no partial or complete bundle branch block) in the population was 1.3% and 0.6%, respectively. Both were significantly associated with an elevated risk of all-cause mortality and cardiovascular mortality. QRS duration ≥ 110 ms doubled the risk of SCD, and IVCD was associated with a three-fold higher risk of SCD. Two percent of the subjects presented with wide frontal QRS-T angle ≥ 100° (the angle between the QRS axis and the T-wave axis in the frontal plane). A wide QRS-T angle was associated with higher overall mortality and more than doubled the risk of SCD, which was mainly due to an abnormal T-wave axis. Inverted T-waves in the right precordial leads (V1–V3) or beyond were present in 0.5% of the population. No increase in mortality or SCD was associated with right precordial T-wave inversions. In contrast, inverted T-waves in other leads than V1–V3 were associated with higher risk of cardiovascular mortality and SCD. Altogether 2.1% of the study participants presented with a prolonged PR interval > 200 ms. No rise in overall mortality, SCD, or hospitalizations due to heart failure, atrial fibrillation, or stroke was observed among these subjects during the follow-up period. In conclusion, of the electrocardiographic parameters studied, prolonged QRS duration, IVCD, and wide QRS-T angle are associated with SCD in the general population, and such changes in an ECG should therefore alert the physician to more closely evaluate and follow the patient. On the other hand, a prolonged PR interval and right precordial T-wave inversions seem to have no prognostic implications in the absence of other features suggestive of underlying heart disease. / Tiivistelmä Sydänperäinen äkkikuolema on yleisin kuolinsyy länsimaissa, missä puolet sydänkuolemista ja 15–20 % kokonaiskuolleisuudesta johtuu äkillisestä sydänpysähdyksestä. Sepelvaltimotauti on yleisin taustalla oleva syy, ja jopa puolessa sepelvaltimotautikuolemista äkkikuolema on taudin ensimmäinen oire. Jo pitkään on yritetty kehittää menetelmiä, joilla voitaisiin tunnistaa suurimmassa äkkikuoleman vaarassa olevat. 12-kanavainen EKG on laajalti käytössä oleva tutkimus, jolla tutkitaan sydämen sähköistä toimintaa, mutta sydänperäistä äkkikuolemaa spesifisti väestössä ennustavia EKG-poikkeavuuksia ei ole juuri pystytty osoittamaan. Tämän väitöskirjatyön tarkoituksena oli tutkia, miten EKG:ssä nähtävät ilmiöt kuten QRS kompleksin kesto, QRS-kompleksin ja T-aallon välinen kulma, kääntyneet T-aallot sekä PR-aika korreloivat ennusteeseen väestötasolla. Tutkimme 10899 suomalaisen keski-ikäisen henkilön (52 % miehiä) EKG:t, jotka oli rekisteröity 1966–1972, ja seurasimme tutkittavia keskimäärin 30 (± 11) vuotta. Leventynyt QRS kompleksi ≥ 110 ms löytyi 1.3 %:lta ja epäspesifi kammionsisäinen johtumishäiriö eli IVCD (QRS ≥ 110 ms ilman osittaista tai täydellistä haarakatkosta) 0.6 %:lta tutkituista. Molemmat muutokset liittyivät lisääntyneeseen kokonaiskuolleisuuteen sekä sydänkuoleman riskiin. QRS kompleksin kesto ≥ 110 ms assosioitui lisäksi kaksinkertaiseen ja IVCD kolminkertaiseen äkkikuolemariskiin. 2 %:lla tutkituista sydänlihaksen depolarisaation suuntaa kuvaavan QRS-kompleksin akselin ja repolarisaatiota kuvaavan T-aallon akselin välinen frontaalitason QRS-T kulma oli leveä ≥ 100°. Näillä henkilöillä kokonaiskuolleisuus oli lisääntynyt, ja sydänperäisen äkkikuoleman riski oli yli kaksinkertainen verrattuna henkilöihin jolla QRS-T kulma oli  < 100°. Oikeanpuoleisissa rintakytkennöissä V1–V3 todettiin negatiiviset T-aallot 0.5 %:lla tutkituista, mutta näillä ei ollut vaikutusta kuolleisuuteen. Sen sijaan henkilöillä, joilla todettiin negatiiviset T-aallot muissa kytkennöissä, oli yli kaksinkertainen sydänkuoleman ja äkillisen sydänpysähdyksen vaara muihin tutkittuihin verrattuna. Osallistujista 2.1 %:lla todettiin pidentynyt PR-aika > 200 ms. Tämä ei kuitenkaan vaikuttanut henkilöiden kuolleisuuteen eikä sydämen vajaatoiminnasta, eteisvärinästä tai aivoverenkiertohäiriöistä johtuvien sairaalahoitojen määrään. Tutkituista EKG:n poikkeavuuksista siis pidentynyt QRS-kompleksin kesto, IVCD ja leveä QRS-T kulma liittyvät selvästi lisääntyneeseen äkillisen sydänpysähdyksen riskiin. Sen sijaan pidentynyt PR-aika tai T-inversiot oikeanpuoleisissa rintakytkennöissä ilman muuta viitettä sydänsairaudesta eivät vaikuta ennusteeseen keski-ikäisessä väestössä.

Tolkningen av EKG är en viktig metod vid diagnostisering av onormala hjärttillstånd och kan användas i förebyggande syfte att upptäcka tidigare okända hjärtproblem. Att enkelt kunna mäta sitt EKG och få det analyserat och presenterat på ett pedagogiskt sätt utan att behöva rådfråga en läkare är något det finns ett konsumentbehov av. Denna rapport beskriver hur en EKG-signal behandlas med olika algoritmer och metoder i syfte att detektera hjärtslag och dess olika parametrar. Denna information används till att klassificera varje hjärtslag för sig och därmed avgöra om användaren har en normal eller onormal hjärtfunktion. För att nå dit har en mjukvaruprototyp utvecklats där algoritmerna implementerats. En enkätundersökning gjordes i syfte att undersöka hur utdata från mjukvaruprototypen skulle presenteras för en vanlig användare utan medicinsk utbildning. Sju filer med EKG-signaler från MIT-BIH Arrhythmia Database användes för testning av mjukvaruprototypen. Resultatet visade att prototypen kunde detektera en rad olika hjärtfel som låg till grund vid fastställning om hjärtat slog normalt eller onormalt. Resultatet presenterades på en mobilapp baserad på enkätundersökningen. / The interpretation of the ECG is an important method in the diagnosis of abnormal heart conditions and can be used proactively to discover previ-ously unknown heart problems. Being able to easily measure the ECG and get it analyzed and presented in a clear manner without having to consult a doctor is improtant to satisfy consumer needs. This report describes how an ECG signal is treated with different algo-rithms and methods to detect the heartbeat and its various parameters. This information is used to classify each heartbeat separately and thus determine whether the user has a normal or abnormal cardiac function. To achieve this a software prototype was developed in which the algorithms were implemented. A questionnaire survey was done in order to examine how the output of the software prototype should be presented for a user with no medical training. Seven ECG files from MIT-BIH Arrhythmia database were used for validation of the algorithms. The developed algorithms could detect of if any abnormality of heart function occurred and informed the users to consult a physician. The presentation of the heart function was based on the result from the questioner.

Abstrakt: Inom vården används olika undersökningsmetoder för att kunna utvärdera hjärtats funktion. Elektrokardiografi (EKG) är en av de metoderna. EKG har många fördelar exempelvis är metoden tillgänglig, billig, riskfri och icke-invasiv. Vid vilo-EKG placeras tio elektroder på bestämda positioner på kroppen vilka ger upphov till 12 avledningar. Avledningarna indelas i två grupper: bröstavledningar och extremitetavledningar. Studiens syfte var att undersöka närmare om det finns skillnader som påverkar bedömningen av EKG:et i P- vågor, QRS- komplex och hjärtats elektriska axel (QRS el-axel) i extremitetavledningar mellan standardkoppling och två andra omkopplingar. Trettio frivilliga deltagare inkluderades i denna studie. För samtliga deltagare registrerades tre EKG:n. I det första EKG:et kopplades extremitetselektroderna enligt standardkopplingen. I det andra EKG:et kopplades armelektroder på höger och vänstra överarmar, vänster benelektroden kopplades på lårbenet. Det tredje EKG:et kopplades enligt Mason- Liker, förutom att höger benelektrod inte omplacerades. Vid alla tre EKG:na placerades bröstelektroderna enligt standardkopplingen. Förändringar i duration, amplitud, och QRS el-axel mellan dessa EKG:n undersöktes. Resultaten av studien visade att det inte fanns någon signifikant skillnad mellan dessa kopplingar i duration och amplitud i QRS-komplexen. Inte heller i durationen på P-vågen. Däremot påvisades en signifikant skillnad i QRS el-axel samt i amplitud på P-vågen för den ena omkopplingen.

Fragmented QRS (fQRS) is a marker of conduction block due to myocardial scar that presents in electrocardiography (ECG) as an additional one or more R wave (R') or notching in the S wave nadir in contiguous leads. However, fQRS description on premature ventricular contractions (PVCs) has not been previously described. We describe a case of a 67-year-old male with a past medical history of prediabetes, hypertension and coronary artery disease who presented after an ophthalmic procedure with asymptomatic PVCs and episodes of bigeminy. Initial ECG showed an isolated fQRS in V2. However, during PVCs significant extrasystoles fragmentation was seen in other coronary territories. Upon reviewing his most recent cardiac catheterization, it showed a 40% ostial and 70% distal left anterior descending stenosis with a mid-segment patent stent, 95% first diagonal stenosis and totally occluded proximal right coronary artery. Identification of diffuse fQRS known to be associated with myocardial scar, sustained arrhythmic events and sudden cardiac death, particularly when seen in the inferior leads, became extremely relevant in our patient. We noted that ejection fraction reduction from 52% to 34% on his last coronary intervention was crucial to decide if an implantable cardioverter-defibrillator would be needed. PVC fragmentation might be a new ECG marker that could uncover both scar and arrhythmia potential in patients at risk of adverse cardiac events.

No description available.

This project considers methods of construction QRS detectors. It focus in detection complexes of QRS single leads and space speed, which are calculated from three orthogonal leads. In theory was refer to various methods, which lead to design detector. It were designed two algoritms (constant and adaptive detecting threshold), which were implemented into detector and the signal was preprocessed by Hilbert transformation. Toward algoritms were completed by modification, which improved detection effectivity. Function of algoritms were tested in all signals of CSE (V2,V5,aVF).

A Miocardiopatia hipertrófica foi descrita há mais de 50 anos e é a cardiopatia de causa genética mais comum no mundo. Pacientes portadores de miocardiopatia hipertrófica podem apresentar maior risco de eventos arrítmicos graves e morte súbita. Assim torna-se importante o desenvolvimento de técnicas de rastreio desse subgrupo de pacientes para, quando necessário, indicar tratamento específico como o implante de CDI. O realce tardio é a manifestação de fibrose nos exames de imagem como tomografia computadorizada do coração e/ou ressonância cardíaca em pacientes com cardiopatias e quando presente em grandes quantidades, pode estar relacionado a maior incidência de eventos fatais. O eletrocardiograma é ferramenta de baixo custo, não invasiva e difundida nos serviços de saúde brasileiros. O objetivo desse estudo é avaliar a correlação entre a presença e localização de realce tardio na tomografia computadorizada do coração e o achado de fibrose pelo escore de Selvester no eletrocardiograma de repouso de portadores de MCPH, determinar a prevalência de fibrose miocárdica entre os pacientes, comparando a sensibilidade, especificidade, valor preditivo positivo e negativo do escore de Selvester. Foram analisados 112 pacientes do ambulatório de miocardiopatia do Instituto Dante Pazzanese de Cardiologia portadores de miocardiopatia hipertrófica sendo incluídos 75 desses. Foram divididos em dois grupos: Portadores de CDI com 60 pacientes e sem CDI com 15 pacientes. Foram coletados dados clínicos, ecocardiográficos, eletrocardiografia digital e tomografia computadorizada do coração. Foram realizados os cálculos do escore de Selvester e a mensuração e localização de realce tardio nos cortes tomográficos dos pacientes. A correlação dos resultados foi analisada pelo método de regressão linear. As características e frequências mais marcantes do grupo foram sexo masculino 49,4%, idade 41,63 ± 15,16, classe funcional I/II - NYHA 90,6%, fibrilação atrial 21,3%, baixa prevalência de comorbidades como hipertensão arterial 37,3%, diabetes 4%, dislipidemia 17,3%, clearence de creatinina > 60mL/min em 100% e ausência de doença coronariana estabelecida, fração de ejeção do ventrículo esquerdo preservada de 69,9 ± 5,46, medida do septo interventricular de 21,04 ± 6,23 e prevalência de gradiente > 30mmHg na via de saída do ventrículo esquerdo de 37,3%. Dos fatores de risco clássicos, morte súbita familiar e história de síncope eram as mais prevalentes com 57,3% cada, o uso do beta-bloqueador ocorreu em 89,3%. A massa de fibrose pela tomografia computadorizada foi de 9,87 ± 10,79 equivalendo a porcentagem de 5,66 ± 6,16, tendo prevalência em 88% da amostra. Já pelo escore de Selvester, encontramos 8,44 ± 7,39 de porcentagem de fibrose com prevalência de 76%. Na análise de kappa para a variável categórica fibrose entre o escore de Selvester e a tomografia computadorizada do coração, foi encontrada fraca correlação com r = 0,38 (p < 0,01). Enquanto variável contínua aplicando o método de regressão linear, foi encontrada correlação forte com r = 0,7 (p < 0,01). A sensibilidade, especificidade, valor preditivo positivo e valor preditivo negativo do escore de Selvester para o diagnóstico de fibrose foram de, respectivamente, 84,8%, 88,8%, 98,2% e 44,4%. A localização da fibrose apresentou correlação fraca entre os métodos com r = 0,16 (p < 0,01). Os dados desse estudo indicam que há moderada correlação entre o escore de Selvester e o realce tardio pela tomografia computadorizada na quantificação de fibrose em pacientes portadores de miocardiopatia hipertrófica. / Hypertrophic cardiomyopathy is considered the most common genetic cardiovascular disease and has been recognized for 50 years. Patients with hypertrophic cardiomyopathy may present risk of arrhythmic events and sudden cardiac death. Thus, it is important to develop screening techniques for this subgroup of patients to indicate, when necessary, specific treatment as implantable cardioverter defibrillator. Late enhancement is fibrosis manifestation in images exam as multidetector computed tomography and/or magnetic cardiac resonance and if present in large quantities may be related to a higher incidence of fatal events. The electrocardiogram is a low-cost, non-invasive tool that is present in most Brazilian health services. The purpose of this study was to test the presence and location correlation between the Selvester and the late enhancement in the multidetector computed tomography, to determine the prevalence of myocardial fibrosis among patients, comparing the sensitivity, specificity, positive and negative predictive value of the Selvester QRS score. A total of 112 patients from the Institute of Cardiology Dante Pazzanese outpatient clinic with hypertrophic cardiomyopathy were analyzed, and 75 of them were included. They were divided into two groups: ICD patients with 60 patients and no ICD with 15 patients. Clinical, echocardiographic, digital electrocardiography and computed tomography of the heart were collected. The Selvester score was calculated and the measurement and location of late enhancement in the tomographic sections of the patients were performed. The correlation of the results was analyzed by the linear regression. The most remarkable features and frequencies of the group were male gender 49.4%, age 41.63 ± 15.16 years, functional class I / II - NYHA 90.6%, atrial fibrillation 21.3%, low prevalence of comorbidities as hypertension 37.3%, diabetes 4%, dyslipidemia 17.3%, creatinine clearance > 60mL/min in 100% and absence of known coronary artery disease, left ventricular ejection fraction preserved 69.9 ± 5.46, measured of the interventricular septum 21.04 ± 6.23 and prevalence of gradient > 30mmHg in the left ventricular outflow tract 37.3%. Classic risk factors as sudden family death and history of syncope were the most prevalent 57.3% each, the use of beta-blocker occurred in 89.3%. The mass of fibrosis by multidetector computed tomography was 9.87 ± 10.79g, representing a percentage of 5.66 ± 6.16, with a prevalence of 88% of the sample. Selvester QRS score, was found 8.44 ± 7.39 percent of fibrosis with a prevalence of 76%. In the kappa analysis for the categorical variable between the Selvester score and the computed tomography of the heart, we found a weak correlation r = 0.38 (p <0.01), as a continuous variable applying the linear regression, a strong correlation was found r = 0.7 (p <0.01). The sensitivity, specificity, positive predictive value and negative predictive value of the Selvester QRS score for the diagnosis of fibrosis were 84.8%, 88.8%, 98.2% and 44.4%, respectively. The location of the fibrosis showed weak correlation between the methods r = 0.16 (p <0.01). The results of this study indicate there is a moderate correlation between the Selvester QRS score and the late enhancement by multidetector computed tomography in the quantification of fibrosis in patients with hypertrophic cardiomyopathy.

Electrocardiography (ECG) has been established as one of the most useful diagnostic tools in medicine and is critical in the management of various heart conditions. Automated or semi-automated ECG analysis algorithms are expected to play an important role in the utilization of the ECG data. The correct identification of the QRS complexes is a fundamental step in every ECG analysis method. A major problem that is often encountered in automatic QRS detection is the presence of artifacts in the ECG data, which cause considerable alterations to the signal. Some common filters can smooth the effect of the artifacts, however they cannot eliminate them due to their spectral frequency overlap with the signal components. In this thesis, the objective was to develop a method, based on Time-Frequency Analysis that would be able to automatically detect and remove artifacts in order to increase the reliability of automatic QRS detection. The ECG data used for this purpose was taken from the Physionet library and more specifically from the MIMIC II database. The data in this database was acquired from ICU patients and it contains various types of rhythms as well as artifacts. First, a Graphical User Interface (GUI) was developed in order to manually annotate ECG data and was used for creating the ground truth for testing the methods developed. The Time-Frequency Analysis method used for the analysis of the ECG data, was based on a time-varying Autoregressive (AR) model whose solutions were obtained using Burg’s method. Several factors that affect the effectiveness of the method were investigated in order to optimize the algorithm experimentally. The algorithm implemented performs three main functions: “Artifact Hypothesis Testing,” “Artifact Detection and Removal,” and “QRS Complex Detection.” The first step, “Artifact Hypothesis Testing,” examines whether the signal contains any artifact or not. This is performed with a correct classification rate of 95.56%. The second step was the “Artifact Detection and Removal,” which could detect and remove the artifact area with an accuracy of 95.60% based on each signal sample identified as artifact or not. The final step, the “QRS Complex Detection,” correctly identified 92% of QRS complexes (322 out of 335 annotated QRS complexes). Finally, the proposed method was compared with one of the most commonly used methods in ECG analysis, the Wavelet Transform Analysis (WTA). The two methods were tested on exactly the same dataset. The WTA resulted in an overall score of 65.3% mainly due to the large number of false positive detections in the regions of artifact. / Το ηλεκτροκαρδιογράφημα (ΗΚΓ) έχει καθιερωθεί ως ένα από τα πιο χρήσιμα εργαλεία διάγνωσης στην ιατρική και είναι πολύ σημαντικό στη διαχείριση καρδιαγγειακών παθήσεων. Αυτοματοποιημένοι ή ημι-αυτοματοποιημένοι αλγόριθμοι ανάλυσης του ΗΚΓ αναμένεται να έχουν σημαντικό ρόλο στη χρήση των δεδομένων του ΗΚΓ. Η σωστή αναγνώριση των συμπλεγμάτων QRS είναι βασικό βήμα σε κάθε μέθοδο ανάλυσης του ΗΚΓ. Ένα σημαντικό πρόβλημα που συχνά προκύπτει σε αυτόματη ανίχνευση QRS είναι η παρουσία των τεχνητών σφαλμάτων (artifacts) στα δεδομένα ΗΚΓ, τα οποία προκαλούν σημαντικές αλλαγές στο σήμα. Κάποια κοινά φίλτρα μπορούν να εξομαλύνουν τις επιπτώσεις των τεχνητών σφαλμάτων, ωστόσο δεν μπορούν να τα εξαλείψουν λόγω της μεγάλης επικάλυψης του φάσματος συχνοτήτων τους με αυτού των στοιχείων του σήματος. Στην παρούσα εργασία στόχος ήταν η ανάπτυξη μιας μεθόδου, βασισμένης στην Ανάλυση Χρόνου-Συχνότητας, που θα είναι σε θέση να εντοπίσει αυτόματα και να αφαιρεί τα τεχνητά σφάλματα, ώστε να έχουμε μια πιο αξιόπιστη μέθοδο αυτόματης ανίχνευσης των QRS. Τα δεδομένα ΗΚΓ που χρησιμοποιήθηκαν για το σκοπό αυτό λήφθηκαν από τη βιβλιοθήκη Physionet και πιο συγκεκριμένα από τη βάση δεδομένων MIMIC II. Τα δεδομένα σε αυτή τη βάση δεδομένων προέρχονται από ασθενείς της Μονάδας Εντατικής Θεραπείας, και ως εκ τούτου, περιέχουν διάφορα είδη ρυθμών αλλά και τεχνητών σφαλμάτων. Αρχικά, ένα Γραφικό Περιβάλλον Χρήστη (GUI), σχεδιάστηκε για τη χειροκίνητη σηματοδότηση των διάφορων περιοχών ΗΚΓ σημάτων και χρησιμοποιήθηκε για τη δημιουργία των αληθών αποτελεσμάτων για δοκιμή της μεθόδου. H Ανάλυση Χρόνου-Συχνότητας έγινε με τη χρήση ενός χρονικά μεταβαλλόμενου Αυτοπαλινδρομικού (AR) μοντέλου οι λύσεις του οποίου βρέθηκαν με τη μέθοδο Burg. Ακολούθησε η διερεύνηση διαφόρων παραγόντων που επηρεάζουν την αποτελεσματικότητα της μεθόδου, προκειμένου να βελτιστοποιηθεί πειραματικά η μέθοδος. Ο αλγόριθμος που υλοποιήθηκε εκτελεί τρεις βασικές λειτουργίες: “Artifact Hypothesis Testing,” “Artifact Detection and Removal” και “QRS Complex Detection.” Κατ’ αρχήν, το βήμα "Artifact Hypothesis Testing" εξετάζει αν το σήμα περιέχει τεχνητό σφάλμα ή όχι, με το ποσοστό σωστής ταξινόμησης να ανέρχεται στο 95.56%. Το δεύτερο βήμα, η ανίχνευση και αφαίρεση της περιοχής του τεχνητού σφάλματος, έγινε με ακρίβεια 95.60% με βάση το πόσα σημεία του σήματος αναγνωρίστηκαν ως τεχνητό σφάλμα ή όχι. Τέλος, το συνολικό ποσοστό ορθής ανίχνευσης των συμπλεγμάτων QRS ήταν 92% (322 από τα 335 QRS που επισημάνθηκαν χειροκίνητα). Τέλος, έγινε μια σύγκριση μεταξύ της προτεινόμενης μεθόδου και μιας μεθόδου ανάλυσης ΗΚΓ που χρησιμοποιείται πολύ συχνά, της ανάλυσης με Μετασχηματισμό Wavelet (WTA). Οι δύο μέθοδοι δοκιμάστηκαν στα ίδια ακριβώς δεδομένα. Η ορθή ανίχνευση των συμπλεγμάτων QRS με τη μέθοδο WTA ήταν 65.3% κυρίως λόγω του μεγάλου αριθμού ψευδώς θετικών αποτελεσμάτων στις περιοχές των τεχνητών σφαλμάτων.

A Miocardiopatia hipertrófica foi descrita há mais de 50 anos e é a cardiopatia de causa genética mais comum no mundo. Pacientes portadores de miocardiopatia hipertrófica podem apresentar maior risco de eventos arrítmicos graves e morte súbita. Assim torna-se importante o desenvolvimento de técnicas de rastreio desse subgrupo de pacientes para, quando necessário, indicar tratamento específico como o implante de CDI. O realce tardio é a manifestação de fibrose nos exames de imagem como tomografia computadorizada do coração e/ou ressonância cardíaca em pacientes com cardiopatias e quando presente em grandes quantidades, pode estar relacionado a maior incidência de eventos fatais. O eletrocardiograma é ferramenta de baixo custo, não invasiva e difundida nos serviços de saúde brasileiros. O objetivo desse estudo é avaliar a correlação entre a presença e localização de realce tardio na tomografia computadorizada do coração e o achado de fibrose pelo escore de Selvester no eletrocardiograma de repouso de portadores de MCPH, determinar a prevalência de fibrose miocárdica entre os pacientes, comparando a sensibilidade, especificidade, valor preditivo positivo e negativo do escore de Selvester. Foram analisados 112 pacientes do ambulatório de miocardiopatia do Instituto Dante Pazzanese de Cardiologia portadores de miocardiopatia hipertrófica sendo incluídos 75 desses. Foram divididos em dois grupos: Portadores de CDI com 60 pacientes e sem CDI com 15 pacientes. Foram coletados dados clínicos, ecocardiográficos, eletrocardiografia digital e tomografia computadorizada do coração. Foram realizados os cálculos do escore de Selvester e a mensuração e localização de realce tardio nos cortes tomográficos dos pacientes. A correlação dos resultados foi analisada pelo método de regressão linear. As características e frequências mais marcantes do grupo foram sexo masculino 49,4%, idade 41,63 ± 15,16, classe funcional I/II - NYHA 90,6%, fibrilação atrial 21,3%, baixa prevalência de comorbidades como hipertensão arterial 37,3%, diabetes 4%, dislipidemia 17,3%, clearence de creatinina > 60mL/min em 100% e ausência de doença coronariana estabelecida, fração de ejeção do ventrículo esquerdo preservada de 69,9 ± 5,46, medida do septo interventricular de 21,04 ± 6,23 e prevalência de gradiente > 30mmHg na via de saída do ventrículo esquerdo de 37,3%. Dos fatores de risco clássicos, morte súbita familiar e história de síncope eram as mais prevalentes com 57,3% cada, o uso do beta-bloqueador ocorreu em 89,3%. A massa de fibrose pela tomografia computadorizada foi de 9,87 ± 10,79 equivalendo a porcentagem de 5,66 ± 6,16, tendo prevalência em 88% da amostra. Já pelo escore de Selvester, encontramos 8,44 ± 7,39 de porcentagem de fibrose com prevalência de 76%. Na análise de kappa para a variável categórica fibrose entre o escore de Selvester e a tomografia computadorizada do coração, foi encontrada fraca correlação com r = 0,38 (p < 0,01). Enquanto variável contínua aplicando o método de regressão linear, foi encontrada correlação forte com r = 0,7 (p < 0,01). A sensibilidade, especificidade, valor preditivo positivo e valor preditivo negativo do escore de Selvester para o diagnóstico de fibrose foram de, respectivamente, 84,8%, 88,8%, 98,2% e 44,4%. A localização da fibrose apresentou correlação fraca entre os métodos com r = 0,16 (p < 0,01). Os dados desse estudo indicam que há moderada correlação entre o escore de Selvester e o realce tardio pela tomografia computadorizada na quantificação de fibrose em pacientes portadores de miocardiopatia hipertrófica. / Hypertrophic cardiomyopathy is considered the most common genetic cardiovascular disease and has been recognized for 50 years. Patients with hypertrophic cardiomyopathy may present risk of arrhythmic events and sudden cardiac death. Thus, it is important to develop screening techniques for this subgroup of patients to indicate, when necessary, specific treatment as implantable cardioverter defibrillator. Late enhancement is fibrosis manifestation in images exam as multidetector computed tomography and/or magnetic cardiac resonance and if present in large quantities may be related to a higher incidence of fatal events. The electrocardiogram is a low-cost, non-invasive tool that is present in most Brazilian health services. The purpose of this study was to test the presence and location correlation between the Selvester and the late enhancement in the multidetector computed tomography, to determine the prevalence of myocardial fibrosis among patients, comparing the sensitivity, specificity, positive and negative predictive value of the Selvester QRS score. A total of 112 patients from the Institute of Cardiology Dante Pazzanese outpatient clinic with hypertrophic cardiomyopathy were analyzed, and 75 of them were included. They were divided into two groups: ICD patients with 60 patients and no ICD with 15 patients. Clinical, echocardiographic, digital electrocardiography and computed tomography of the heart were collected. The Selvester score was calculated and the measurement and location of late enhancement in the tomographic sections of the patients were performed. The correlation of the results was analyzed by the linear regression. The most remarkable features and frequencies of the group were male gender 49.4%, age 41.63 ± 15.16 years, functional class I / II - NYHA 90.6%, atrial fibrillation 21.3%, low prevalence of comorbidities as hypertension 37.3%, diabetes 4%, dyslipidemia 17.3%, creatinine clearance > 60mL/min in 100% and absence of known coronary artery disease, left ventricular ejection fraction preserved 69.9 ± 5.46, measured of the interventricular septum 21.04 ± 6.23 and prevalence of gradient > 30mmHg in the left ventricular outflow tract 37.3%. Classic risk factors as sudden family death and history of syncope were the most prevalent 57.3% each, the use of beta-blocker occurred in 89.3%. The mass of fibrosis by multidetector computed tomography was 9.87 ± 10.79g, representing a percentage of 5.66 ± 6.16, with a prevalence of 88% of the sample. Selvester QRS score, was found 8.44 ± 7.39 percent of fibrosis with a prevalence of 76%. In the kappa analysis for the categorical variable between the Selvester score and the computed tomography of the heart, we found a weak correlation r = 0.38 (p <0.01), as a continuous variable applying the linear regression, a strong correlation was found r = 0.7 (p <0.01). The sensitivity, specificity, positive predictive value and negative predictive value of the Selvester QRS score for the diagnosis of fibrosis were 84.8%, 88.8%, 98.2% and 44.4%, respectively. The location of the fibrosis showed weak correlation between the methods r = 0.16 (p <0.01). The results of this study indicate there is a moderate correlation between the Selvester QRS score and the late enhancement by multidetector computed tomography in the quantification of fibrosis in patients with hypertrophic cardiomyopathy.

Abstract Based on experimental studies, heterogeneous ventricular repolarization has been suggested to predispose to the onset of life-threatening ventricular arrhythmias and subsequent studies in various patient populations have associated it with poor clinical outcome. The aim of this study was to assess the dynamics of ventricular repolarization from electrocardiogram (ECG) during a standard exercise stress test with techniques based on principal component analysis, and to investigate whether they would yield valuable prognostic information on cardiac mortality and sudden cardiac death. Exercise ECG recordings from 40 healthy men and women were analyzed in order to establish normal dynamics and rate-dependence for the spatial QRS/T angle and total cosine R to T (TCRT), which reflects the spatial deviation between the depolarization and repolarization wave-fronts. Subsequently, exercise ECG recordings from 20 patients with previous myocardial infarction (MI) were compared with 20 controls in order to assess the modulation of previous MI on the dynamics of TCRT. The prognostic value of abnormal dynamics and rate-dependence of TCRT and spatial QRS/T angle were assessed in 1,297 patients referred to a clinically indicated exercise stress test. The spatial QRS/T angle and TCRT were found to be significantly rate-dependent during both exercise and recovery periods as TCRT and the cosine of the spatial QRS/T angle decreased at higher heart rates (HR), indicating increase in the global heterogeneity of the ventricular repolarization. In the post-MI group, the dynamics of TCRT were impaired with a significantly lower rate-dependence in contrast to the healthy and control groups. In the study cohort, impaired rate-dependence of TCRT during both exercise and recovery periods was an independent predictor of cardiac and sudden cardiac death during the follow up of the study. Similarly, reduction of the area between the exercise and three-minute recovery TCRT/HR curves was associated with an increased risk of cardiac and sudden cardiac death. In conclusion, dynamics and rate-dependence of TCRT and spatial QRS/T angle are able to discriminate subjects with an increased risk of cardiac and sudden cardiac death. Reduced rate-dependence of TCRT during exercise and recovery periods, as well as decreased exercise-recovery hysteresis of TCRT, are significant predictors of cardiac and sudden cardiac death. / Tiivistelmä Sydämen kammioiden poikkeavan palautumisen on kokeellisissa tutkimuksissa havaittu altistavan kammioperäisille rytmihäiriöille. Lisäksi, useat tutkimukset erilaisissa potilasaineistoissa ovat osoittaneet sen olevan yhteydessä heikkoon kliiniseen ennusteeseen. Tämän työn tarkoituksena oli analysoida sydämen kammioiden repolarisaation dynamiikkaa sydänsähkökäyrästä (EKG) rasituskokeen aikana pääkomponenttianalyysiin perustuvilla menetelmillä sekä tutkia, ennustavatko uudet muuttujat sydänperäistä kuolemaa tai sydänperäistä äkkikuolemaa. Neljänkymmenen terveen miehen ja naisen rasitus-EKG:t analysoitiin depolarisaatio- ja repolarisaatioaaltojen välistä avaruudellista kulmaa kuvaavan ’total cosine R to T’:n (TCRT) sekä kolmiulotteisen QRS/T-kulman dynamiikan sekä sykeriippuvuuden normaaliarvojen määrittämiseksi. Lisäksi, vertailtiin 20 sydäninfarktin sairastaneen sekä 20 kontrollipotilaan rasitusmittauksia aiemman infarktin TCRT:n dynamiikkaan sekä sykeriippuvuuteen aiheuttaman modulaation määrittämiseksi. Muuttujien poikkeavan dynamiikan ennustearvoa testattiin 1297 rasitus-EKG-mittaukseen lähetteen saaneella potilaalla. Sekä TCRT että avaruudellisen QRS/T-kulman kosini olivat molemmat erittäin sykeriippuvaisia sekä rasituksessa että palautumisessa. Molemmat muuttujat pienenivät sykkeen (HR) kasvaessa, osoittaen kammioiden repolarisaation heterogeenisyyden kasvua korkeammilla syketaajuuksilla. Sydäninfarktin sairastaneilla potilailla muuttujien dynamiikka ja sykeriippuvuus olivat heikentyneitä. Kohorttiaineistossa heikentynyt sykeriippuvuus sekä rasituksen että palautumisen aikana ennustivat myöhempää sydänperäistä kuolemaa sekä sydänperäistä äkkikuolemaa itsenäisesti. Vastaavasti, rasituksen ja kolmen minuutin palautumisen aikaisten TCRT/HR kuvaajien väliin jäävän pinta-alan pienentyminen oli yhteydessä korkeampaan sydänperäisen kuoleman sekä sydänperäisen äkkikuoleman riskiin. Kammioiden repolarisaation dynamiikkaa kuvaavat muuttujat pystyvät erottelemaan potilaat, joilla on korkeampi riski kokea sydänperäinen kuolema tai sydänperäinen äkkikuolema. Poikkeavan alhainen sykeriippuvuus rasituksen ja palautumisen aikana sekä alentunut rasituksen ja palautumisen välinen hystereesi olivat merkittäviä sydänperäisen kuoleman sekä sydänperäisen äkkikuoleman ennustajia.