Efficacy of Antibiotic Prophylaxis Before the Implantation of Pacemakers and Cardioverter-Defibrillators Results of a Large, Prospective, Randomized, Double-Blinded, Placebo-Controlled Trial

Background-Although routinely administered, definitive evidence for the benefits of prophylactic antibiotics before the implantation of permanent pacemakers and implantable cardioverter-defibrillators from a large double-blinded placebo-controlled trial is lacking. The purpose of this study was to determine whether prophylactic antibiotic administration reduces the incidence of infection related to device implantation. Methods and Results-This double blinded study included 1000 consecutive patients who presented for primary device (Pacemaker and implantable cardioverter-defibrillators) implantation or generator replacement randomized in a 1:1 fashion to prophylactic antibiotics or placebo. Intravenous administration of I g of cefazolin (group 1) or placebo (group 2) was done immediately before the procedure. Follow-up was performed 10 days, 1, 3, and 6 months after discharge. The primary end point was any evidence of infection at the surgical incision (pulse generator pocket), or systemic infection related to be procedure. The safety committee interrupted the trial after 649 patients were enrolled due to a significant difference in favor of the antibiotic arm (group 1: 2 of 314 infected patients-0.63%; group 11: 11 of 335 to 3.28%; RR=0.19; P=0.016). The following risk factors were positively correlated with infection by univariate analysis: nonuse of preventive antibiotic (P=0.016); implant procedures (versus generator replacement: P=0.02); presence of postoperative hematoma (P=0.03) and procedure duration (P=0.009). Multivariable analysis identified nonuse of antibiotic (P=0.037) and postoperative hematoma (P=0.023) as independent predictors of infection. Conclusions-Anti biotic prophylaxis significantly reduces infectious complications in patients undergoing implantation of pacemakers or cardioverter-defibrillators. (Circ Arrhythmia Electrophysiol. 2009;2:29-34.)

Predictors of Mortality in Patients with Chagas` Cardiomyopathy and Ventricular Tachycardia Not Treated with Implantable Cardioverter-Defibrillators

Methods: We assessed the outcome of 56 patients with Chagas` cardiomyopathy ([31 men]; mean age of 55 years; mean left ventricular ejection fraction [LVEF] 42%) presenting with either sustained ventricular tachycardia (VT) or nonsustained VT (NSVT), before therapy with implantable cardioverter-defibrillator was available at our center. Results: Over a mean follow-up of 38 +/- 16 months (range, 1-61 months), 16 patients (29%) died, 11 due to sudden cardiac death (SCD), and five from progressive heart failure. Survivors and nonsurvivors had comparable baseline characteristics, except for a lower LVEF (46 +/- 7% vs 31 +/- 9%, P < 0.001) and a higher New York Heart Association class (P = 0.003) in those who died during follow-up. Receiver-operator characteristic curve analysis showed that an LVEF cutoff value of 38% had the best accuracy for predicting all-cause mortality and an LVEF cutoff value of 40% had the best accuracy for prediction of SCD. Using the multivariate Cox regression analysis, LVEF < 40% was the only predictor of all-cause mortality (hazard ratio [HR] 12.22, 95% confidence interval [CI] 3.46-43.17, P = 0.0001) and SCD (HR 6.58, 95% CI 1.74-24.88, P = 0.005). Conclusions: Patients with Chagas` cardiomyopathy presenting with either sustained VT or NSVT run a major risk for mortality when had concomitant severe or even moderate LV systolic dysfunction. (PACE 2011; 54-62).

Cardiac arrhythmia emergency room visits and environmental air pollution in Sao Paulo, Brazil

Objectives: Air-pollution exposure has been associated with increased cardiovascular hospital admissions and mortality in time-series studies. We evaluated the relation between air pollutants and emergency room (ER) visits because of cardiac arrhythmia in a cardiology hospital. Methods: In a time-series study, we evaluated the association between the emergency room visits as a result of cardiac arrhythmia and daily variations in SO2, CO, NO2, O-3 and PM10, from January 1998 to August 1999. The cases of arrhythmia were modelled using generalised linear Poisson regression models, controlling for seasonality (short-term and long-term trend), and weather. Results: Interquartile range increases in CO (1.5 ppm), NO2 (49,5 mu g/m(3)) and PM10 (22.2 mu g/m(3)) on the concurrent day were associated with increases of 12.3% (95% CI: 7.6% to 17.2%), 10.4% (95% CI: 5.2% to 15.9%) and 6.7% (95% CI: 1.2% to 12.4%) in arrhythmia ER visits, respectively. PM10, CO and NO2 effects were dose-dependent and gaseous pollutants had thresholds. Only CO effect resisted estimates in models with more than one pollutant. Conclusions: Our results showed that air pollutant effects on arrhythmia are predominantly acute starting at concentrations below air quality standards, and the association with CO and NO2 suggests a relevant role for pollution caused by cars.

Chagas disease

Chagas disease is a chronic, systemic, parasitic infection caused by the protozoan Trypanosoma cruzi, and was discovered in 1909. The disease affects about 8 million people in Latin America, of whom 30-40% either have or will develop cardiomyopathy, digestive megasyndromes, or both. In the past three decades, the control and management of Chagas disease has undergone several improvements. Large-scale vector control programmes and screening of blood donors have reduced disease incidence and prevalence. Although more effective trypanocidal drugs are needed, treatment with benznidazole (or nifurtimox) is reasonably safe and effective, and is now recommended for a widened range of patients. Improved models for risk stratification are available, and certain guided treatments could halt or reverse disease progression. By contrast, some challenges remain: Chagas disease is becoming an emerging health problem in non-endemic areas because of growing population movements; early detection and treatment of asymptomatic individuals are underused; and the potential benefits of novel therapies (eg, implantable cardioverter defibrillators) need assessment in prospective randomised trials.

T-wave alternans: desempenho clínico, limitações, metodologias de análise

Reconhecer com precisão indivíduos com maior risco imediato de morte súbita cardíaca (MSC) ainda é uma questão em aberto. A natureza fortuita dos eventos cardiovasculares agudos não parece se adequar ao conhecido modelo de indução de taquicardia/fibrilação ventricular por um gatilho em sincronia a um substrato arritmogênico estático. Quanto ao mecanismo da MSC, uma instabilidade elétrica dinâmica explicaria melhor a raridade da associação simultânea de um gatilho certo a um substrato cardíaco apropriado. Diversos estudos tentaram medir essa instabilidade elétrica cardíaca (ou um equivalente válido) em uma sequência de batimentos cardíacos no ECG. Dentre os mecanismos possíveis podemos citar o prolongamento do QT, dispersão do QT, potenciais tardios, alternância de onda T ou T-wave alternans (TWA), e turbulência da frequência cardíaca. Este artigo se atém em particular ao papel da TWA no panorama atual da estratificação de risco cardíaco. Os achados sobre TWA ainda são heterogêneos, variando de um desempenho prognóstico muito bom até um quase nulo, dependendo da população clínica observada e protocolo clínico usado. Para preencher as atuais lacunas no conhecimento sobre TWA, profissionais médicos e pesquisadores devem explorar melhor as características técnicas das diversas tecnologias disponíveis para a avaliação de TWA e atentar ao fato de que os valores de TWA respondem a diversos outros fatores, além de medicamentos. Informações sobre mecanismos celulares e subcelulares da TWA estão fora do escopo deste artigo, mas são referenciados alguns dos principais trabalhos sobre este tópico, com o intuito de auxiliar no entendimento dos conceitos e fatos cobertos neste artigo.

Prevention of Venous Thrombosis by Warfarin after Permanent Transvenous Leads Implantation in High-Risk Patients

Background: The incidence of venous lesions following transvenous cardiac device implantation is high. Previous implantation of temporary leads ipsilateral to the permanent devices, and a depressed left ventricular ejection fraction have been associated with an increased risk of venous lesions, though the effects of preventive strategies remain controversial. This randomized trial examined the effects of warfarin in the prevention of these complications in high-risk patients. Method: Between February 2004 and September 2007, we studied 101 adults who underwent a first cardiac device implantation, and who had a left ventricular ejection fraction <= 0.40, or a temporary pacing system ipsilateral to the permanent implant, or both. After device implantation, the patients were randomly assigned to warfarin to a target international normalized ratio of 2.0-3.5, or to placebo. Clinical and laboratory evaluations were performed regularly up to 6 months postimplant. Venous lesions were detected at 6 months by digital subtraction venography. Results: Venous obstructions of various degrees were observed in 46 of the 92 patients (50.0%) who underwent venography. The frequency of venous obstructions was 60.4% in the placebo, versus 38.6% in the warfarin group (P = 0.018), corresponding to an absolute risk reduction of 22% (relative risk = 0.63; 95% confidence interval = 0.013-0.42). Conclusions: Warfarin prophylaxis lowered the frequency of venous lesions after transvenous devices implantation in high-risk patients. (PACE 2009; 32:S247-S251)