Search

Background: Chagas disease (ChD) will become predominantly a disease of the elderly, as a consequence of the effectiveness of control measures in many Latin American countries. The effects of the disease in old age have received little attention. We investigated the effects of ageing in the association between cardiac vagal impairment, a typical feature of ChD, and chronic Trypanosoma cruzi infection., Methods: The study sample of this cross-sectional study consists of 1014 subjects ≥ 60 years old (mean age = 68.3; SD = 6.9) residing in Bambuí City (Southeast Brazil). ECG was recorded and one-breath sinus arrhythmia test was performed. Maximal expiratory over the minimal inspiratory (E:I) ratio and heart rate variability (HRV) measurements were calculated. Ordinal logistic regression was used to assess the relation between vagal indexes and chronic T. cruzi infection., Results: The prevalence of T. cruzi infection was 32.0% and of major ECG abnormalities, 43.4%. Among individuals aged 60-69 years, T. cruzi infection was significantly and independently associated with reduced SDNN (OR 0.38; 95% CI 0.27-0.53), RMSSD (OR 0.48; 0.34-0.67) and EI: ratio (OR 0.45; 95% CI 0.33-0.63). Among individuals aged >70 years, no significant odds ratios were found in either the unadjusted or the adjusted analysis. The presence of major ECG abnormalities did not affect the association between vagal indexes and T. cruzi infection., Conclusions: Disease-specific vagal cardiac dysfunction was observed in ChD individuals below 70. However, further ageing interferes significantly with vagal heart modulation, attenuating the difference of HRV indexes between ChD and non-ChD subjects., (Copyright © 2009 Elsevier Ireland Ltd. All rights reserved.)

Aims: The effects of exercise training in chronic heart failure are well established, however, they have not been evaluated in Chagas cardiomyopathy (ChC). We sought to determine the effects of exercise training on functional capacity, health-related quality of life (HQoL), and brain natriuretic peptide (BNP) levels in patients with ChC., Methods and Results: This randomized, controlled, single-blind trial included 40 patients with ChC (age 49.5 +/- 7.8 years, 57.5% male) who did not practice regular exercise. All patients were assessed, at baseline and at the end of the study, by exercise test (VO(2) and exercise time), six-minute walk test (6MWT), Goldman Specific Activity Scale (SAS), HQoL, and BNP levels. Patients were randomized to inactive control group (ICG = 19) or exercise training group (ETG = 21). Exercise training group patients underwent 12 weeks of exercise training: walking for up to 30 min (intensity 50-70% HR reserve + HR at rest) and warm-up and cooling-down exercising, three times a week. The data were analysed for delta values (Delta= end - baseline). After intervention, compared with the ICG, the ETG had significant increases in functional parameters including, DeltaVO(2) (6.5 vs. 2.8 mL/kg/min, P = 0.001), Delta exercise time (2.9 vs.1.1 min, P < 0.001), Delta6MWT distance (83.5 vs. 2.0 m, P = 0.001) improved DeltaSAS (8 vs. 1 patient, P = 0.008), and HQoL: Delta domains vitality (7.5 vs. 0 points, P = 0.013), Delta emotional aspects (16.7 vs. 0 points, P = 0.012), and Delta mental health (16.1 vs. 0 points, P = 0.031). There was no difference in BNP levels., Conclusion: In patients with ChC, exercise training was associated with a major improvement in functional capacity and HQoL without any adverse effects.

In this study, the authors aimed to investigate the prognostic value of brain-type natriuretic peptide (BNP) for all-cause mortality among persons with Chagas disease, a parasitic disease caused by the protozoan Trypanosoma cruzi. The authors used data on 1,398 participants (37.5% infected with T. cruzi) aged 60 years and over from the Bambuí Cohort Study of Aging in Brazil. From 1997 to 2007, 512 participants died, leading to 12,406 person-years of observation. The hazard ratio for death was 1.27 for each unit of log-transformed BNP level (95% confidence interval (CI: 1.11, 1.45) among infected persons, independent of potentially confounding factors. Infected persons with baseline BNP levels in the top quartile had a risk of death twice that of persons in the bottom quartile (hazard ratio = 2.07, 95% CI: 1.29, 3.32). The discriminatory ability of BNP in predicting mortality (C = 0.69, 95% CI: 0.66, 0.71) was similar to that of an electrocardiogram (C = 0.68, 95% CI: 0.65, 0.71), with reasonably stable risk discrimination over time. BNP is a strong predictor of mortality in older adults with Chagas disease. Although the usefulness of BNP for risk stratification in this parasitic disease remains a topic of debate, this study found that BNP-based risk discrimination is at least comparable to that of an electrocardiogram.

Background: Although cardiovascular diseases are the main cause of morbimortality in Brazil, the access of small-town populations to electrocardiography and cardiology assessment is limited. The use of telecardiology to assist the access of distant towns to electrocardiography and a second opinion in cardiology is promising; however, it has not been formally assessed., Objective: To assess the feasibility of implementing a low-cost public telecardiology system in small Brazilian towns., Methods: A total of 82 towns in the state of Minas Gerais, with a population < 10,500 inhabitants, presenting > 70% coverage by the Family Health Program (Programa Saude da Familia-PSF), local government compliance and internet access, were selected. Each town was supplied with digital electrocardiography (ECG) device and a team was trained. The implementation was coordinated by HC/UFMG, together with four university hospitals in the state of Minas Gerais (UFU, UFTM, UFJF and UNIMONTES). The ECG assessments were carried out in the towns and sent through the Internet for prompt analysis by an on-duty telecardiology team. Online and offline discussions on the medical cases were carried out through the Internet, as well as refreshment courses., Results: During the implementation period, a total of 253 health professionals were trained. From July 2006 to November 2008, the project assisted 42,664 patients, with a total of 62,865 ECG assessments being performed. A total of 2,148 emergency cases were treated, as well as 420 teleconsultations. The intermediate evaluation showed good acceptance of the implemented technology and a 70% decrease in patient referrals to other reference centers., Conclusion: The use of the customary resources in informatics to assist the access of small-town populations to electrocardiography and specialized cardiology assessment is feasible.

Background: APVT is an invasive method recommended for symptomatic patients with PAH that permits the identification of the minority of patients (<20%) that may benefit from long-term calcium channel blockers. Adenosine has been indicated in guidelines as a vasodilator agent of choice for APVT, although it has not been directly compared with iNO, the gold standard for this test. The objective of the study was to compare adenosine with inhaled nitric oxide (iNO) for acute pulmonary vasoreactivity testing (APVT) in pulmonary arterial hypertension (PAH), in order to determine the efficacy and safety of the first in the clinical setting., Methods: The measurements of cardiac output, pulmonary and systemic resistance were done in the basal state and with a stepwise increase of the dose of each drug until either maximum dosage (adenosine: 500 microg/kg/min or iNO: 80 ppm) or side effects observed or a positive response were reached, according to current guidelines. The order of drugs used in each test was consecutively alternated during the study., Results: Six of the 39 studied patients (15%) presented a positive response to iNO; none to adenosine (p = 0.047, McNemar's test). Twenty-three patients (59%) did not reach the maximum dose of adenosine due to side effects, including bronchospasm, thoracic pain and bradycardia., Conclusions: APVT testing with adenosine was not able to detect PAH patients responsive to iNo and provoked frequent adverse effects. Adenosine should not be used as a vasodilator drug in APVT., (Copyright 2009 Elsevier Ltd. All rights reserved.)

Systematic reviews with meta-analysis of studies on diagnostic tests or prognostic factors are research tools that are still being developed. The objective of the present paper is to describe the methodology of systematic review and meta-analysis of this type of studies, step by step. A literature review on the subject was made, the recommendations were compiled and the paper was organized in: a) Introduction, b) Details on the eight steps to be followed, c) Form of publication of a systematic review with meta-analysis, and d) Conclusion. The systematic review methods were thoroughly described with a critical analysis of the methods of statistical compilation of results, with emphasis on the utilization of the Summary Receiver Operator Characteristic curve. References for the details of each statistical technique used were provided in the meta-analysis. We concluded that systematic reviews with meta-analysis of diagnostic tests or prognostic factors are useful in data compilation of various studies on the same subject, since they reduce biases and increase the statistical power of the primary research.

Background: Limited clinical data suggest that chronic Trypanosoma cruzi infection, which causes Chagas' disease (ChD), is associated with cognitive impairment. This study investigated this association in a large population-based sample of older adults., Methods: Participants in this cross-sectional study comprised 1,449 persons aged > or = 60 years from a Brazilian endemic area (Bambuí). Cognitive functioning was ascertained by the Mini-Mental State Examination (MMSE), considering its score in percentiles [< or =14 (<5th percentile), 15-22 (5th to <25th) and > or =23]. Hypothesized risk factors were T. cruzi infection, ChD-related electrocardiographic (ECG) abnormalities and use of digoxin medication. Potential confounders included depressive symptoms, smoking, stroke, hemoglobin, HDL cholesterol, blood glucose, systolic blood pressure, and use of psychoactive medication., Results: The prevalence of T. cruzi infection was 37.6%. There was a graded and independent association between infection and the MMSE score (adjusted odds ratios estimated by ordinal logistic regression = 1.99; 95% CI 1.43-2.76). No significant associations between the MMSE score and ECG abnormalities or digoxin medication use were found., Conclusions: This study provides for the first time epidemiological evidence of an association between T. cruzi infection and cognitive impairment which was not mediated by either ChD-related ECG abnormalities or digoxin medication use., (2008 S. Karger AG, Basel.)

Background: Left ventricular dysfunction (LVd) is the main predictor of mortality in Chagas disease (ChD)., Aims: To compare the diagnostic performance of the conventional approach (ECG and chest X-ray) in the recognition of LVd in ChD, with a new strategy, in which BNP is measured in patients with an abnormal ECG., Methods: Consecutive ChD patients recruited at an Outpatient Reference Center in Belo Horizonte, Brazil, without other systemic diseases, in 1998-99 (sample 1, n = 165) and in 2001-02 (sample 2, n = 62) underwent ECG, chest X-ray, BNP measurement and echocardiography., Results: The prevalence of LVd (ejection fraction

Objective: To assess the use of the active orthostatic stress test for detecting vagal dysfunction in patients with Chagas' disease with preserved overall systolic function, and to compare it with the respiratory sinus arrhythmia test., Methods: Sixty-one chagasic patients (Ch) and 38 nonchagasic (NCh) patients with no significant evidence of heart disease or systemic diseases underwent Doppler echocardiography and autonomic function tests. The respiratory sinus arrhythmia test was performed through electrocardiographic recording during deep breathing, at 6 ripm, calculating the E:I ratio (mean ratio between the longest expiratory RR interval and the shortest inspiratory RR interval at each cycle). The electrocardiogram was recorded during the act of standing and during the following 30 seconds (active orthostatic stress test), and the max RR/min RR ratio (the longest and shortest RR intervals right after change in posture) was calculated. The indices were adjusted for significant covariables., Results: The max RR/min RR ratio (NCh: 1.52 [1.44-1.74] x Ch: 1.43 [1.33-1.51], P < 0.001) and the E:I ratio (NCh: 1.38 +/- 0.02 x Ch: 1.25 +/- 0.02, P<0.001) were lower among chagasic patients. A high correlation was observed between the adjusted max RR/min RR ratio and E:I ratio (r = 0.628, P < 0.001), but neither significantly correlated with left ventricular ejection fraction., Conclusion: Chagasic patients with preserved left ventricular overall systolic function showed a significant reduction in the vagal indices obtained on short-lasting tests, as compared with normal controls. The active orthostatic stress test that, showed a good correlation with the respiratory sinus arrhythmia maneuver, constituted a valid option for the outpatient care assessment of vagal control.

Background: AutoCapture (AC) is a programmable feature that enables the pacemaker to both track the capture threshold and automatically adjust the output on a beat-by-beat basis. Although AC safely and significantly reduces the current drainage, some authors have argued that the longevity benefit of such a system is overstated. This study aims to estimate the longevity extension that can be obtained, in the clinical routine, by turning the AC on in comparison to pacemakers programmed to operate at the shipped and manually optimized output., Methods: We selected 83 consecutive patients who received implanted St Jude's Affinity pacemakers >6 months earlier. Eight patients died or were lost to follow-up and in 9 subjects the AC could not be turned on. In the remaining 66 patients, current drain and estimated longevity were compared in 3 situations: (1) AC on; (2) AC off, optimized programming (100%-150% voltage threshold); (3) AC off, shipped output (3.5 V)., Results: Five patients had large variations (>1 V) of the AC threshold. Current drainage was 8.0 +/- 0.9 mA in the AC group, 8.7 +/- 1.8 mA with AC off and optimized programming, and 11.3 +/- 2.3 mA at shipped output (P <.01). Estimated longevity was significantly extended (P <.01) by AC (12.1 +/- 1.0 years) when compared to shipped (8.9 +/- 1.7 years) and optimized programming (11.3 +/- 1.4 years)., Conclusion: Reprogramming the pacemaker output significantly enhanced its estimated longevity; AC added a moderate but significant extension over manual reprogramming and was associated with increased safety in patients with large ventricular threshold variations.

Heart rate turbulence (HRT) quantifies the biphasic response of the sinus node to ventricular premature complexes (VPCs) and is a powerful electrocardiogram related risk predictor. VPCs are frequent in Chagas disease, a potentially lethal illness, and can hamper the analysis by conventional methods of autonomic heart control. The aim of the study was to examine HRT in patients with Chagas disease. Chagas disease patients and healthy controls (group 0, n = 11) without other diseases were submitted to a standardized protocol, including electrocardiogram, echocardiography, and 24-hour Holter monitoring. Chagas disease patients were divided according to their left ventricular systolic function: normal (group 1, n = 103) and reduced ejection fraction (group 2, n = 23). Two HRT indices, turbulence onset (TO) and turbulence slope (TS), were calculated and compared among groups after adjustment for covariates like the prevalence of VPCs and the mean heart rate. Chagas disease patients had significantly altered TO (group 1: -0.0186, group 2: -0.0126) and TS (group 1: 10.844, group 2: 7.870) values in comparison with controls (TO -0.0256, TS 19.829); P < 0.001 for both comparisons. In conclusion, HRT data may be useful in the electrocardiographic analysis of autonomic heart control in Chagas disease. Its prognostic value remains to be determined.

Chagas disease is caused by a protozoan parasite, Trypanosoma cruzi, and infects over 15 million people worldwide. New cases of the disease are now uncommon, mainly due to national control programs in Latin America. However, there is a large reservoir of chronically infected patients, many of whom will develop chagasic cardiopathy. Here, the clinical diagnosis and management of Chagas cardiopathy are discussed. Particular emphasis is placed on the clinical staging of patients and the use of various diagnostic tests that may be useful in individualizing treatment of the two most relevant clinical syndromes, ie. heart failure and arrhythmias. Finally, the relevance of specific treatment is discussed, stressing the important role of parasite persistence for disease pathogenesis.

Left ventricular dysfunction in Chagas' disease is common but can be difficult to detect. We investigated whether measurement of plasma brain natriuretic peptide (BNP) could identify patients with left ventricular dysfunction who need further investigation or treatment. Among patients with an abnormal electrocardiogram or chest radiograph, a BNP concentration of 60.7 pmol/L or higher has a sensitivity and positive predictive value of 80%, and specificity and negative predictive value of 97%. Measurement of plasma BNP concentration could be a useful method to screen patients with Chagas' disease.

Beta slope is a nonlinear index derived from the power-law analysis of 24-hour heart rate variability (HRV); in healthy subjects, the beta index is typically near -1, suggesting a fractal behavior of HRV. There is scarce data on HRV in Chagas' disease. This transversal study intends to describe power-law and linear HRV patterns in different forms of Chagas' disease. Patients and healthy controls (n = 26) without other diseases were submitted to a standardized protocol, including electrocardiography, echocardiography, and 24-hour Holter monitoring. Patients with Chagas' disease were divided into groups according to their left ventricular (LV) systolic function: normal (group 1, n = 85), segmental abnormalities (group 2, n = 49), and reduced ejection fraction (group 3, n = 26). The temporal series were carefully processed to obtain the HRV indexes and beta slope. Despite the differences in the LV systolic function, the 3 groups were comparable in terms of long-term HRV index values. After adjustment for covariates, short-term HRV index values were consistently reduced in the Chagas' disease groups. The beta-index values were also diminished in Chagas' disease groups (group 1: -1.09 +/- 0.03, group 2: -1.11 +/- 0.06; group 3: -1.14 +/- 0.03; and controls: 0.95 +/- 0.03, p <0.001). This breakdown of fractal long-range correlation of RR interval dynamics, a strong predictor of mortality in other cardiomyopathies, may reflect cardiac dysautonomia that may have gone undetected in long-term time-domain analysis. This abnormality may explain the increased risk for arrhythmic sudden death found in Chagas' disease even in the absence of signs of LV dysfunction.