RESUMO
AIMS: The effect of right ventricular (RV) pacing on left ventricular (LV) function has been extensively evaluated, but the effect on RV function per se has not been evaluated systematically. We aimed to assess the effect of dual chamber pacemaker on RV function. METHODS AND RESULTS: All consecutive patients undergoing dual chamber pacemaker from January 2018 to March 2019 for AV block with a structurally normal heart were included. They underwent pre-procedure detailed echocardiography (including three-dimensional [3D] RV ejection fraction [RVEF]), a screening echocardiogram 2 days after pacemaker implantation and again a detailed echocardiogram at 6-month follow-up. We compared the baseline echocardiographic RV parameters with those 6 months after the pacemaker implantation. A total of 60 patients underwent successful pacemaker implantation. At 6 months, most of the patients were pacemaker dependent with pacing percentage of 98.9% ± 2.4%; there was a significant increase in TR and a mean drop in RVEF by 2.8 ± 5%, with 23 (38.3%) having at least a 5% decrease in RVEF. The drop in RVEF positively correlated with TR vena contracta at 6 months but did not correlate with pulmonary artery systolic pressure at 6 months. CONCLUSION: Our study shows the presence of demonstrable RV dysfunction as early as 6 months in a majority of patients who have undergone pacemaker implantation.
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Estimulação Cardíaca Artificial/métodos , Marca-Passo Artificial , Disfunção Ventricular Direita/fisiopatologia , Disfunção Ventricular Direita/terapia , Idoso , Ecocardiografia , Feminino , Humanos , Masculino , Estudos Prospectivos , Disfunção Ventricular Direita/diagnóstico por imagemRESUMO
BACKGROUND: Eleven criteria correlating electrocardiogram (ECG) findings with reduced left ventricular ejection fraction (LVEF) have been previously published. These have not been compared head-to-head in a single study. We studied their value as a screening test to identify patients with reduced LVEF estimated by cardiac magnetic resonance (CMR) imaging. METHODS: ECGs and CMR from 548 patients (age 61 + 11 years, 79% male) with previous myocardial infarction (MI), from the DETERMINE and PRE-DETERMINE studies, were analyzed. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of each criterion for identifying patients with LVEF ≤ 30% and ≤ 40% were studied. A useful screening test should have high sensitivity and NPV. RESULTS: Mean LVEF was 40% (SD = 11%); 264 patients (48.2%) had LVEF ≤ 40%, and 96 patients (17.5%) had LVEF ≤ 30%. Six of 11 criteria were associated with a significant lower LVEF, but had poor sensitivity to identify LVEF ≤ 30% (range 2.1%-55.2%) or LVEF ≤ 40% (1.1%-51.1%); NPVs were good for LVEF ≤ 30% (range 82.8%-85.9%) but not for LVEF ≤ 40% (range 52.1%-60.6%). Goldberger's third criterion (RV4/SV4 < 1) and combinations of maximal QRS duration > 124 ms + either Goldberger's third criterion or Goldberger's first criterion (SV1 or SV2 + RV5 or RV6 ≥ 3.5 mV) had high specificity (95.4%-100%) for LVEF ≤ 40%, although seen in only 48 (8.8%) patients; predictive values were similar on subgroup analysis. CONCLUSIONS: None of the ECG criteria qualified as a good screening test. Three criteria had high specificity for LVEF ≤ 40%, although seen in < 9% of patients. Whether other ECG criteria can better identify LV dysfunction remains to be determined.
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Eletrocardiografia/métodos , Infarto do Miocárdio/fisiopatologia , Disfunção Ventricular Esquerda/diagnóstico , Disfunção Ventricular Esquerda/fisiopatologia , Feminino , Ventrículos do Coração/diagnóstico por imagem , Ventrículos do Coração/fisiopatologia , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
Aims: There is an almost endless controversy regarding the choice of the QT correction formula to be used in electrocardiograms (ECG) in neonates for screening for long QT syndrome (LQTS). We compared the performance of four commonly used formulae and a new formula derived from neonates. Methods and results: From a cohort of 44 596 healthy neonates prospectively studied in Italy between 2001 and 2006, 5000 ECGs including 17 with LQTS-causing mutation identified by genotyping were studied using four QT correction formulae [Bazett's (QTcB), Fridericia's (QTcF), Framingham (QTcL), and Hodges (QTcH)]. A neonate-specific exponential correction (QTcNeo) was derived using 2500 randomly selected ECGs and validated for accuracy in the remaining 2500 ECGs. Digital ECGs were recorded between the 15th and 25th day of life; QT interval was measured manually in leads II, V5, and V6. To assess the ability to provide heart rate (HR) independent QT correction, regression analysis of the QTc-HR plots for all 5000 ECGs with each correction formula was done. QTcB provided the most HR independent correction with a slope closest to zero (slope +0.086 ms/b.p.m.) followed by QTcF (slope -0.308 ms/b.p.m.), QTcL (slope -0.364 ms/b.p.m.), and QTcH (slope +0.962 ms/b.p.m.). The QTc-HR slope of QTcNeo (QT/RR0.467) was similar to QTcB. The ability to correctly identify neonates with LQTS was best with QTcB, QTcF, and QTcNeo (comparable areas under the receiver operating characteristic curves) with positive predictive value of 39-40% and sensitivity of 100%. Cut-off values were 460 ms for QTcB, 394 ms for QTcF, and 446 ms for QTcNeo. Conclusions: The Bazett's correction provides an effective HR independent QT correction and also accurately identifies the neonates affected by LQTS. It can be used with confidence in neonates, although other methods could also be used with appropriate cut-offs.
Assuntos
Eletrocardiografia/métodos , Eletrocardiografia/estatística & dados numéricos , Síndrome do QT Longo/diagnóstico , Triagem Neonatal/métodos , Interpretação Estatística de Dados , Feminino , Frequência Cardíaca , Humanos , Recém-Nascido , Masculino , Valor Preditivo dos Testes , Estudos Prospectivos , Análise de RegressãoRESUMO
INTRODUCTION: There are few published studies on reference ranges of ECG parameters in children; some ethnic differences have been described. METHODS: We studied digital 12lead ECGs (1000â¯samples/s) from 906 healthy rural Indian children (467 boys: 439 girls) aged 5-15â¯years. PR, QRS, and QT were measured using superimposed median beat. Age-wise normal limits (median, 2nd and 98th percentile) were defined. RESULTS: Heart rate decreased while PR interval and QRS duration increased with age. QTcB interval remained unchanged from 5 to 12â¯years and decreased thereafter due to QTcB shortening in boys but not in girls. "Juvenile T wave pattern" was seen in 95% of children aged 5-8â¯years in lead V1 and 55-60% in V2, V3; it decreased with age. RV dominance (R/Sâ¯>â¯1) in lead V1 was seen in 13% at 5â¯years, 1% at 10â¯years and none at 14â¯years. CONCLUSION: Reference ranges in Indian children are similar to those in other ethnic groups.
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Fenômenos Fisiológicos Cardiovasculares , Ecocardiografia , Eletrocardiografia , Adolescente , Criança , Pré-Escolar , Feminino , Humanos , Índia , Masculino , Valores de ReferênciaRESUMO
Takotsubo cardiomyopathy (TTC) is a well-known entity. We present two rare presentations of the same. Our first patient was diagnosed to have hypertrophic cardiomyopathy with ventricular tachycardia (VT), for which an ICD had been implanted. He later developed acute TTC with a large left ventricular (LV) apical thrombus. Our second patient was a 59 year old lady diagnosed to have TTC 2 years ago, from which she had recovered completely. She recently developed a recurrence of the same.
Assuntos
Complicações do Diabetes/complicações , Emoções , Cardiomiopatia de Takotsubo/etiologia , Cardiomiopatia de Takotsubo/terapia , Ecocardiografia , Eletrocardiografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Cardiomiopatia de Takotsubo/fisiopatologiaRESUMO
BACKGROUND: The spatial QRS-T angle is ideally derived from orthogonal leads. We compared the spatial QRS-T angle derived from orthogonal leads reconstructed from digital 12-lead ECGs and from digital Holter ECGs recorded with the Mason-Likar (M-L) electrode positions. METHODS AND RESULTS: Orthogonal leads were constructed by the inverse Dower method and used to calculate spatial QRS-T angle by (1) a vector method and (2) a net amplitude method, in 100 volunteers. Spatial QRS-T angles from standard and M-L ECGs differed significantly (57°±18° vs 48°±20° respectively using net amplitude method and 53°±28° vs 48°±23° respectively by vector method; p<0.001). Difference in amplitudes in leads V4-V6 was also observed between Holter and standard ECGs, probably due to a difference in electrical potential at the central terminal. CONCLUSION: Mean spatial QRS-T angles derived from standard and M-L lead systems differed by 5°-9°. Though statistically significant, these differences may not be clinically significant.
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Diagnóstico por Computador/normas , Eletrocardiografia Ambulatorial/instrumentação , Eletrocardiografia Ambulatorial/métodos , Eletrodos , Processamento de Sinais Assistido por Computador/instrumentação , Diagnóstico por Computador/instrumentação , Desenho de Equipamento , Análise de Falha de Equipamento , Humanos , Valores de Referência , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
Healthcare provider institutions in India now offer structured health check-up 'packages' for routine screening of common diseases. While some tests included within their ambit are in keeping with international and Indian recommendations, some are entirely unwarranted. Unnecessary and inappropriate screening tests may cause more harm than benefit. Besides financial and resource burden, there may be over-diagnosis and over-treatment, psychological distress due to false-positive test results, harm from invasive follow-up tests, and false reassurance due to false-negative test results. Clinicians must ensure a net benefit from tests and interventions in order to efficiently deliver preventive services. We reviewed current screening guidelines for cardiovascular disease and common cancers, and surveyed multiple 'packages' provided at 8 centres in Mumbai, India. We put forth our recommendations for routine health screening in asymptomatic adults in India.
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Programas de Rastreamento , Adulto , Doenças Cardiovasculares/diagnóstico , Feminino , Humanos , Índia , Masculino , Programas de Rastreamento/economia , Programas de Rastreamento/métodos , Pessoa de Meia-Idade , Neoplasias/diagnóstico , Valor Preditivo dos Testes , Medição de RiscoRESUMO
AIM: To study the differences in QTc interval on ECG in response to a single oral dose of rac-sotalol in men and women. METHODS: Continuous 12-lead ECGs were recorded in 28 men and 11 women on a separate baseline day and following a single oral dose of 160 mg rac-sotalol on the following day. ECGs were extracted at prespecified time points and upsampled to 1000 Hz and analyzed manually in a central ECG laboratory on the superimposed median beat. Concentration-QTc analyses were performed using a linear mixed effects model. RESULTS: Rac-sotalol produced a significant reduction in heart rate in men and in women. An individual correction method (QTc I) most effectively removed the heart rate dependency of the QTc interval. Mean QTc I was 10 to 15 ms longer in women at all time points on the baseline day. Rac-sotalol significantly prolonged QTc I in both genders. The largest mean change in QTc I (ΔQTc I) was greater in females (68 ms (95% confidence interval (CI) 59, 76 ms) vs. 27 ms (95% CI 22, 32 ms) in males). Peak rac-sotalol plasma concentration was higher in women than in men (mean Cmax 1.8 µg ml(-1) (range 1.1-2.8) vs. 1.4 µg ml(-1) (range 0.9-1.9), P = 0.0009). The slope of the concentration-ΔQTc I relationship was steeper in women (30 ms per µg ml(-1) vs. 23 ms per µg ml(-1) in men; P = 0.0135). CONCLUSIONS: The study provides evidence for a greater intrinsic sensitivity to rac-sotalol in women than in men for drug-induced delay in cardiac repolarization.
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Antagonistas Adrenérgicos beta/efeitos adversos , Antiarrítmicos/efeitos adversos , Frequência Cardíaca/efeitos dos fármacos , Síndrome do QT Longo/induzido quimicamente , Sotalol/efeitos adversos , Administração Oral , Antagonistas Adrenérgicos beta/administração & dosagem , Antagonistas Adrenérgicos beta/farmacocinética , Antiarrítmicos/administração & dosagem , Antiarrítmicos/farmacocinética , Esquema de Medicação , Eletrocardiografia , Feminino , Humanos , Modelos Lineares , Síndrome do QT Longo/diagnóstico , Síndrome do QT Longo/fisiopatologia , Masculino , Medição de Risco , Fatores de Risco , Fatores Sexuais , Sotalol/administração & dosagem , Sotalol/farmacocinéticaRESUMO
Assessments of cardiac and cardiovascular toxicity are prominent components of drug safety endeavors during drug development and clinical practice. Oncologic drugs bring several challenges to both domains. First, during drug development, it is necessary to adapt the ICH E14 "Thorough QT/QTc Study" because the cytotoxic nature of many oncologics precludes their being administered to healthy individuals. Second, appropriate benefit-risk assessments must be made by regulators: given the benefit these drugs provide in life-threatening illnesses, a greater degree of risk may be acceptable when granting marketing authorization than for drugs for less severe indications. Third, considerable clinical consideration is needed for patients who are receiving and have finished receiving pharmacotherapy. Paradoxically, although such therapy has proved very successful in many cases, with disease states going into remission and patients living for many years after cessation of treatment, cardiotoxicities can manifest themselves relatively soon or up to a decade later. Oncologic drugs have been associated with various off-target cardiovascular responses, including cardiomyopathy leading to heart failure, cardiac dysrhythmias, thromboembolic events, and hypertension. Follow-up attention and care are, therefore, critical. This article reviews the process of benefit-risk estimation, provides an overview of nonclinical and preapproval clinical assessment of cardiovascular safety of oncology drugs, and discusses strategies for monitoring and management of patients receiving drugs with known cardiotoxicity risk. These measures include cardiac function monitoring, limitation of chemotherapy dose, use of anthracycline analogs and cardioprotectants, and early detection of myocardial cell injury using biomarkers.
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Antineoplásicos/uso terapêutico , Cardiotoxicidade/prevenção & controle , Desenho de Fármacos , Animais , Antineoplásicos/efeitos adversos , Cardiotoxicidade/etiologia , Cardiotoxicidade/fisiopatologia , Monitoramento de Medicamentos/métodos , Humanos , Neoplasias/tratamento farmacológico , Medição de Risco/métodos , Fatores de TempoRESUMO
BACKGROUND: Two methods of estimating reader variability (RV) in QT measurements between 12 readers were compared. METHODS: Using data from 500 electrocardiograms (ECGs) analyzed twice by 12 readers, we bootstrapped 1000 datasets each for both methods. In grouped analysis design (GAD), the same 40 ECGs were read twice by all readers. In pairwise analysis design (PAD), 40 ECGs analyzed by each reader in a clinical trial were reanalyzed by the same reader (intra-RV) and also by another reader (inter-RV); thus, variability between each pair of readers was estimated using different ECGs. RESULTS: Inter-RV (mean [95% CI]) between pairs of readers by GAD and PAD was 3.9 ms (2.1-5.5 ms) and 4.1 ms (2.6-5.4 ms), respectively, using ANOVA, 0 ms (-0.0 to 0.4 ms), and 0 ms (-0.7 to 0.6 ms), respectively, by actual difference between readers and 7.7 ms (6.2-9.8 ms) and 7.7 ms (6.6-9.1 ms), respectively, by absolute difference between readers. Intra-RV too was comparable. CONCLUSIONS: RV estimates by the grouped- and pairwise analysis designs are comparable.
Assuntos
Eletrocardiografia/métodos , Eletrocardiografia/estatística & dados numéricos , Frequência Cardíaca/fisiologia , Variações Dependentes do Observador , Projetos de Pesquisa , Análise de Variância , HumanosRESUMO
Lead II is commonly used to study drug-induced QT prolongation. Whether other ECG leads too show comparable QT prolongation is not known. We studied moxifloxacin-induced QT prolongation in a thorough QT study in healthy subjects (54 males, 43 females). Placebo-subtracted change from baseline in QTc corrected by Fridericia's method (ΔΔQTcF) at 1, 1.5, 2 and 4 hours after moxifloxacin was studied in all 12 leads. Unacceptably wide 90% confidence interval (CI) for ΔΔQTcF was seen in three leads; these leads also had maximum ECGs with flat T waves (60% in aVL, 45% in lead III and 42% in V1). After excluding ECGs with flat T waves, 90% lower CI of ΔΔQTcF was ≥ 5 ms in all leads except leads III, aVL and V1 in men. The 90% lower CI exceeded 5 ms in these leads in women despite wide 90% CIs because of greater mean ΔΔQTcF. Leads III, aVL and V1 should be avoided when measuring QT interval in thorough QT studies.
Assuntos
Antibacterianos/efeitos adversos , Eletrocardiografia/métodos , Fluoroquinolonas/efeitos adversos , Síndrome do QT Longo/induzido quimicamente , Síndrome do QT Longo/diagnóstico , Adulto , Feminino , Voluntários Saudáveis , Humanos , Masculino , Pessoa de Meia-Idade , Moxifloxacina , Placebos , Sensibilidade e EspecificidadeRESUMO
Reader variability (RV) results from measurement differences or variability in lead used for QT measurements; the latter is not reflected in conventional methods for estimating RV. Mean and SD of QT intervals in 12 leads of 100 ECGs measured twice were used to simulate data sets with inter-RV of 5, 10, 15, 20, and 25 ms and intra-RV of 3, 6, 9, 12, and 15 ms. Six hundred twenty-five data sets were simulated such that different leads were used in Read1 and Read2 in 0, 10%, 20%, 30%, 40% of ECGs by 25 readers. RV was estimated using ANOVA interaction models: three-way model using Reader, ECG and lead as factors, and 2-way model using reader and ECG as factors. Estimates from three-way model accurately matched inter- and intra-RV that were introduced during simulation regardless of percent of ECGs with lead selection variability. The two-way model provides identical estimates when both reads are in same leads, but higher, more realistically estimates when measurements are made in different leads.
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Arritmias Cardíacas/induzido quimicamente , Arritmias Cardíacas/diagnóstico , Eletrocardiografia/instrumentação , Modelos Estatísticos , Análise de Variância , Simulação por Computador , Humanos , Variações Dependentes do ObservadorRESUMO
The incidence of sudden cardiac death (SCD) is based on studies from North America and Western Europe with very few countries in Asia having conducted robust studies evaluating the occurrence of SCD. This paper reviewed published data on SCD, with a focus on India. In recent years, varying methods of assessment such as verbal autopsies, questionnaires, and quantification of surrogate endpoints such as cardiovascular disease profiles have been used to estimate the incidence of SCD. These studies have shown that the incidence of SCD is on the rise, especially in the urban regions, which may be largely attributed to the increase in prevalence of coronary artery disease, diabetes and hypertension in India. These studies have shown that the risk stratification and management approach for SCD are conspicuously varied and there is a need for establishing a systematic approach for estimating the incidence and risk factors of SCD in India.
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Morte Súbita Cardíaca/epidemiologia , Morte Súbita Cardíaca/etiologia , Morte Súbita Cardíaca/prevenção & controle , Humanos , Incidência , Índia/epidemiologia , Fatores de RiscoRESUMO
INTRODUCTION: We postulated that it may be easier to identify earliest Q onset and latest T offset when the median beats from 12 leads are separated vertically by 5 to 10 mm (ungrouped superimposed median beat [SMB] method) rather than when their baselines closely (but rarely perfectly) overlap (grouped SMB method). METHODS: Three readers manually adjudicated annotations placed by an automated algorithm, using grouped (gSMB) and ungrouped (uSMB) methods in 2658 electrocardiograms (ECGs) recorded in 38 subjects in a crossover design thorough QT study at predose and 6 time points postdosing with placebo or moxifloxacin. RESULTS: Placebo-subtracted, moxifloxacin-induced QTcF prolongation was comparable with both methods. Maximum QTcF prolongation was seen at 2 hours--10.5 milliseconds (90% confidence interval, 7.9-13.1 milliseconds) with gSMB and 12.9 milliseconds (90% confidence interval, 9.9-15.8 milliseconds) by uSMB. Both methods showed good agreement; mean QT was 4 milliseconds greater by uSMB. Interreader variability of absolute differences in QT measurements was 1 millisecond lower with the uSMB method (6.8 ± 5.7 milliseconds by gSMB and 5.9 ± 4.5 milliseconds by uSMB). CONCLUSION: Mean QT was 4 milliseconds longer, and interreader variability, 1 millisecond lower with uSMB. Otherwise, both methods were comparable and detected the moxifloxacin effect.
Assuntos
Algoritmos , Diagnóstico por Computador/métodos , Eletrocardiografia/métodos , Frequência Cardíaca , Síndrome do QT Longo/diagnóstico , Síndrome do QT Longo/fisiopatologia , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Variações Dependentes do Observador , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
INTRODUCTION: Conventionally, QT interval is measured in lead II. There are no data to select an alternative lead for QT measurement when it cannot be measured in Lead II for any reason. METHODS AND RESULTS: We retrospectively analyzed ECGs from 1906 healthy volunteers from 41 phase I studies. QT interval was measured on the median beat in all 12 leads. The mean difference in QT interval between lead aVR and in Lead II was the least, followed by aVF, V5, V6 and V4; lead aVL had maximum difference. The T wave was flat (<0.1 mV) in Lead II in 6.9% of ECGs; it was also flat in 20% of these ECGs (1.4% of all ECGs) in Leads aVR, aVF and V5. CONCLUSIONS: When QT interval cannot be measured in Lead II, the best alternative leads are aVR, aVF, V5, V6 and V4 in that sequence. It differs maximally from that in Lead II in Lead aVL.
Assuntos
Eletrocardiografia/métodos , Sistema de Condução Cardíaco/fisiologia , Feminino , Frequência Cardíaca/fisiologia , Humanos , Síndrome do QT Longo/fisiopatologia , Masculino , Valores de Referência , Estudos RetrospectivosRESUMO
BACKGROUND: Better control of diabetes mellitus reduces microvascular complications, but has limited effect on macrovascular complications including cardiovascular mortality. A spate of controversial reports has shown that some new oral antidiabetic drugs may paradoxically increase cardiovascular events and mortality. We review here published data on cardiac safety of currently available oral antidiabetic drugs. METHODS: Literature search was performed for "cardiovascular risk" and "antidiabetic drugs" or individual oral antidiabetic drugs. RESULTS: Some sulfonylureas increase cardiovascular risk presumably by preventing protective ischemic cardiac preconditioning. Rosiglitazone increases risk of myocardial infarction and death possibly by increasing serum triglycerides and LDL-cholesterol levels. Muraglitazar increased risk of cardiovascular death, myocardial infarction, or stroke due to as yet unidentified reasons. Only insulin sensitizing drugs like metformin and pioglitazone have been consistently shown to reduce cardiovascular risk. Beneficial effects of tight glucose control with insulin or insulin secretagogues on macrovascular complications are inconsistent; their benefits may be negated by increased risk of hypoglycemia which in turn increases adverse cardiovascular events. Increased cardiovascular risk of some antidiabetic drugs was missed during drug development and detected only on meta-analysis of clinical trial data. Regulatory agencies in North America and Europe have therefore proposed stringent guidelines for study design, data analysis and quantification of cardiovascular risk of new antidiabetic drugs. CONCLUSIONS: Physicians should weigh the cardiovascular risk against potential benefits when prescribing antidiabetic medications. The proposed regulatory measures will ensure approval of safer drugs, but may also lengthen the drug development cycle or even deter development of potentially useful drugs.
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Doenças Cardiovasculares , Diabetes Mellitus Tipo 2/tratamento farmacológico , Angiopatias Diabéticas/prevenção & controle , Hipoglicemiantes/administração & dosagem , Hipoglicemiantes/efeitos adversos , Administração Oral , Doenças Cardiovasculares/induzido quimicamente , Doenças Cardiovasculares/prevenção & controle , Ensaios Clínicos como Assunto , Diabetes Mellitus Tipo 2/complicações , Aprovação de Drogas , Humanos , Preparações Farmacêuticas , Fatores de Risco , Resultado do TratamentoRESUMO
INTRODUCTION: We studied moxifloxacin-induced QT prolongation and proportion of categorical QTc outliers when 5 methods of QT measurement were used to analyze electrocardiograms (ECGs) from a thorough QT study. METHODS: QT interval was measured by the threshold, tangent, superimposed median beat, automated global median beat, and longest QT methods in a central ECG laboratory in 2730 digital ECGs from 39 subjects during placebo and moxifloxacin treatment. RESULTS: All 5 methods were able to demonstrate statistically significant moxifloxacin-induced QTcF prolongation. However, lower bound of 95% 1-sided confidence interval of QTcF prolongation did not exceed 5 milliseconds with the longest QT method. More QTcF outliers were observed with the longest QT and tangent methods, whereas the other 3 methods were comparable. QTcF values greater than 500 milliseconds were observed only with moxifloxacin by the tangent method, and with moxifloxacin and placebo by the longest QT method. CONCLUSION: The method of QT measurement must be considered when interpreting individual thorough QT/QTc studies.
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Algoritmos , Artefatos , Diagnóstico por Computador/métodos , Eletrocardiografia/métodos , Síndrome do QT Longo/diagnóstico , Animais , Frequência Cardíaca , Variações Dependentes do Observador , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
A 69-year-old man had numerous episodes of syncope over three years. A head-up tilt test had shown a mixed response and he was labeled as having neurocardiogenic syncope. Lifestyle, dietary and pharmacologic measures were ineffective. At electrophysiology study, an easily inducible, self-terminated AV nodal re-entrant tachycardia was induced. At 1 year follow-up after radiofrequency ablation, he is asymptomatic.
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Ablação por Cateter/métodos , Síncope/diagnóstico , Taquicardia por Reentrada no Nó Atrioventricular/diagnóstico , Idoso , Diagnóstico Diferencial , Eletrocardiografia , Técnicas Eletrofisiológicas Cardíacas , Humanos , Masculino , Síncope/etiologia , Síncope/terapia , Taquicardia por Reentrada no Nó Atrioventricular/complicações , Taquicardia por Reentrada no Nó Atrioventricular/terapia , Teste da Mesa Inclinada , Resultado do TratamentoRESUMO
Background Myocardial infarction (MI) size is a key predictor of prognosis in post-MI patients. Cardiovascular magnetic resonance (CMR) is the gold standard test for MI quantification, but the ECG is less expensive and more widely available. We sought to quantify the relationship between ECG markers and cardiovascular magnetic resonance infarct size. Methods and Results Patients with prior MI enrolled in the DETERMINE (Defibrillators to Reduce Risk by Magnetic Resonance Imaging Evaluation) and PRE-DETERMINE Trial and Registry were included. ECG leads were analyzed for markers of MI: Q waves, fragmented QRS, and T wave inversion. DETERMINE Score=number of leads with [Q waves×2]+[fragmented QRS]+[T wave inversion]. Left ventricular ejection fraction (LVEF) and infarct size as a percentage of left ventricular mass (MI%) were quantified by cardiovascular magnetic resonance. The Modified Selvester Score estimates MI size from 37 ECG criteria. In 551 patients (aged 62.1±10.9 years, 79% men, and LVEF=40.3±11.0%), MI% increased as the number of ECG markers increased (P<0.001). By univariable linear regression, the DETERMINE Score (range 0-26) estimated MI% (R2=0.18, P<0.001) with an accuracy approaching that of LVEF (R2=0.22, P<0.001) and higher than the Modified Selvester Score (R2=0.09, P<0.001). By multivariable linear regression, addition of the DETERMINE Score improved estimation of MI% over LVEF alone (P<0.001) and over Modified Selvester Score alone (P<0.001). Conclusions In patients with prior MI, a simple ECG score estimates infarct size and improves infarct size estimation over LVEF alone. Because infarct size is a powerful prognostic indicator, the DETERMINE Score holds promise as a simple and inexpensive risk assessment tool.