Survival and predictors of survival in patients with congestive heart failure due to Chagas' cardiomyopathy

Risk stratification in a Brazilian hospital-based cohort of 1220 outpatients with heart failure: role of Chagas' heart disease

BACKGROUND

Few studies evaluated prognostic factors of outpatients with heart failure of different etiologies including Chagas' heart disease.

METHODS

We studied 1220 outpatients with heart failure in functional classes III and IV (NYHA) to evaluate prognostic factors. Patients aged 13-72 years (mean 45.5, standard deviation 11); 952 men (78%) and 268 women (22%) were followed up for 25.6+/-26 months from 1991 to 2000. Heart failure was attributed to idiopathic dilated cardiomyopathy in 454 (37%) patients. Etiologies were Chagas' heart disease in 242 (20%) patients, ischemic cardiomyopathy in 212 (17%), hypertensive cardiomyopathy in 170 (14%) and others in 142 (12%). Statistical analyses were performed with Kaplan-Meier and Cox proportional hazards methods, following a strategy of noninvasive model as well as in an invasive model to identify the risk of death.

RESULTS

Four hundred fifteen (34%) patients died in the follow-up period, 71 (6%) patients underwent heart transplantation and 28 (2%) underwent other surgical interventions. In the noninvasive model, Chagas' heart disease (relative risk compared with other etiologies 2.26 to 2.97), left ventricular end diastolic diameter on echocardiography (relative risk 1.13) and left ventricular ejection fraction on radionuclide angiography (relative risk 0.96) were associated with higher mortality. In the invasive model, Chagas' heart disease (relative risk compared with other etiologies 2.66 to 9.13) was the most important determinant of mortality in association with the cardiac index (relative risk 0.40).

CONCLUSIONS

In this cohort of patients with heart failure of different etiologies, Chagas' heart disease was the main prognostic factor for mortality.

Brain natriuretic peptide and left ventricular dysfunction in chagasic cardiomyopathy

Global left ventricular (LV) systolic dysfunction is the strongest predictor of morbidity and mortality in Chagas disease. Echocardiography is considered the gold standard for the detection of LV dysfunction, but not always available in endemic areas where chagasic cardiomyopathy is most common. Brain natriuretic peptide (BNP) is a neurohormone that has been recently described as a simple and inexpensive diagnostic and prognostic marker for patients with congestive heart failure. Chagasic patients (n = 63) and non-infected healthy individuals (n = 18) were recruited prospectively and underwent complete clinical examination, echocardiography and 24-h Holter monitoring. BNP was measured from thawed plasma samples using the Triage BNP test. We observed high levels of BNP in association with depression of LV ejection fraction, with increase of LV end-diastolic diameter and with LV premature complexes. An elevated concentration of BNP, defined as a concentration of 60 pg/ml or more, had a sensitivity of 91.7%, specificity of 82.8%, positive predictive value of 52.4%, and negative predictive value of 98% for detecting LV dysfunction (LV ejection fraction < 40%).BNP measurement using a simple, relatively inexpensive and rapid test has a promising role in identifying LV dysfunction associated with chagasic cardiomyopathy. Equally important, patients with Trypanosoma cruzi infection who have low levels of BNP level in plasma have a very low likelihood of severe cardiac involvement, and echocardiography is probably not necessary.

T-wave axis deviation as an independent predictor of mortality in chronic Chagas' disease

The T-wave axis shift has been reported to represent a general marker of ventricular repolarization abnormalities and a potential indicator of increased risk for cardiovascular mortality. We assessed the prognostic importance of the T-wave axis deviation for mortality rate in patients with chronic Chagas' disease. In a long-term follow-up prospective study, 738 adult outpatients in the chronic phase of Chagas' disease were enrolled. The frontal plane T-wave axis was estimated from 12-lead electrocardiograms obtained on admission and categorized as normal (15 degrees to 75 degrees ), borderline (75 degrees to 105 degrees or 15 degrees to -15 degrees ), and abnormal (>105 degrees or < -15 degrees ). Clinical and radiologic data, 2-dimensional echocardiographic data, and other electrocardiographic data were also recorded. Primary end points were all-cause, those related to Chagas' disease, and sudden cardiac deaths. Statistical analyses included Kaplan-Meier estimation of survival curves and multivariate Cox's proportional hazards models. During a follow-up of 58 +/- 39 months, 62 patients died, 54 from causes related to Chagas' disease and 40 due to sudden cardiac death. Kaplan-Meier survival curves showed that the 3 categories of T axis had significantly different prognoses. Multivariate Cox's survival analysis demonstrated that an abnormal T axis increases the risk of death threefold and sudden death nearly sixfold after adjustment for other covariates, including left ventricular systolic function and other electrocardiographic abnormalities. Borderline T-wave axis also indicated a worse prognosis, particularly in the subgroup of patients with abnormal baseline electrocardiograms. These results indicate that T-wave axis deviation is an easily quantified, strong, and independent mortality risk predictor in patients with chronic Chagas' disease.

Exercise Performance and Skeletal Muscles in Patients With Advanced Chagas Disease

STUDY OBJECTIVE

This study was designed to evaluate the peripheral muscle metabolic and structural characteristics in patients with advanced Chagas disease (ChD), and whether they were related with exercise performance.

DESIGN

Cross-sectional study.

SETTING

Outpatient cardiomyopathy clinic of a university hospital.

PATIENTS AND METHODS

We studied 11 stage II patients, 8 stage III patients, and 11 healthy volunteers. All patients underwent exercise testing and peripheral muscle biopsies. The muscles were also studied in control subjects. Muscle biopsy specimens were analyzed for histochemical characteristics. In six patients, the muscle was studied ultrastructurally.

RESULTS

The data demonstrate more glycolytic and less oxidative capacity of the peripheral muscle in patients with advanced ChD (increased proportion of type IIb fibers, increased proportion of fibers with low nicotinamide adenine dinucleotide diaphorase activity, high proportion of darkly stained fibers for alpha-glycerophosphate dehydrogenase activity, and lower levels of citrate synthase). Many capillaries in patients with ChD had an abnormal aspect: they were either closed or showed a thicker wall. The ultrastructural study also showed fiber atrophy and abnormal capillaries even in patients with normal functional capacity. Some muscle characteristics (enzyme activity, mean cross-sectional area of the fiber, and capillarity) related with exercise parameters (anaerobic threshold, and peak oxygen pulse).

CONCLUSIONS

These findings indicate that patients with advanced ChD have decreased oxidative capacity and a shift to anaerobic metabolism in the skeletal muscle. They also suggest that muscular abnormalities are related to oxygen delivery, which is probably reduced in part by the abnormal muscle microvasculature. Those changes could affect oxygen extraction, and therefore exercise tolerance in these patients.

Elevated concentrations of CCL2 and tumor necrosis factor-alpha in chagasic cardiomyopathy

Chronic myocarditis is the main pathological finding associated with Chagas disease-related morbidity. Concentrations of CCL2, CCL3, tumor necrosis factor (TNF)-alpha, and brain natriuretic peptide (BNP) were evaluated in plasma samples obtained from patients with different clinical forms of chronic chagasic cardiomyopathy. Patients with more-severe Chagas disease had elevated plasma concentrations of TNF-alpha, CCL2, and BNP, and there was a good correlation between levels of these proteins (especially TNF-alpha ) and the degree of heart dysfunction. Indeed, TNF-alpha level was an excellent predictor of heart failure. Peripheral blood mononuclear cell samples obtained from patients with mild or severe chagasic cardiomyopathy produced greater amounts of TNF-alpha and CCL2 than did those obtained from noninfected individuals. The elevation of TNF-alpha and CCL2 levels in the plasma of patients appears to be secondary to the degree of heart dysfunction, whereas spontaneous production of TNF-alpha and CCL2 by mononuclear cells is secondary not only to heart dysfunction, but also to the underlying inflammation in the heart of chagasic patients. Measurement of the TNF-alpha level could be a useful tool in the identification of patients with heart dysfunction who may benefit from further investigation and treatment.

Congestive heart failure in Latin America: the next epidemic

Coronary artery disease is the main cause of congestive heart failure (CHF) in all populations. Latin American countries (LAC) are undergoing the first phase of an epidemic of coronary artery disease that probably will lead to an increased incidence of CHF. The progressive implementation of successful interventions, such as early reperfusion and rehabilitation programs, should increase the survival of patients with acute myocardial infarction and the population at high risk of CHF. The increasing prevalence of risk factors, such as diabetes, hypertension, and obesity, and the ageing of the population may also contribute to a rising incidence of CHF in LAC. Moreover, infectious diseases such as Chagas disease and rheumatic heart disease, known causes of CHF, are still frequent in this population and additionally contribute to the incidence of CHF. If timely preventive interventions are not implemented, CHF could become one of the main contributors to the burden of morbidity, mortality, and health costs in LAC. Properly conducted clinical and epidemiologic studies are needed to identify, implement, and evaluate preventive strategies that are likely to succeed within the specific context of LAC.

The Syrian hamster as a model for the dilated cardiomyopathy of Chagas’ disease: a quantitative echocardiographical and histopathological analysis

Chronic Chagas' disease cardiomyopathy (CCC) is caused by the protozoan Trypanosoma cruzi, and it affects 30% of the 16-18 million people infected in Latin America. A good rodent model that develops a dilated cardiomyopathy closely resembling human CCC after T. cruzi infection is still needed. We compared the cardiomyopathy developed by T. cruzi-infected Syrian hamsters with human Chagas' disease cardiomyopathy using quantitative methods. Female hamsters were infected with 3.5 x 10(4) (G1, n = 10) or 10(5) (G2, n = 10) T. cruzi Y strain blood trypomastigotes. Control animals (C, n = 10) were injected with saline solution. Cardiac function was assessed by echocardiography at 4, 8 and 12 months post-infection. Heart sections were submitted to histopathological/morphometric analysis 12 months post-infection. At this time, ventricular dysfunction and diffuse or multi-focal myocarditis were observed in 91% and 100% of G1 and G2 infected groups, respectively. Median interstitial collagen volumes in groups C, G1 and G2 were 1.2%, 1.9% and 3.9%, respectively, and were significantly higher in group G2 than in group C. Among infected animals, myocarditis showed a positive correlation with interstitial fibrosis. Deaths in the chronic phase (8-12 months post-infection) were more frequent among G2 than G1, and were associated with macroscopic ventricular dilation, severe myocarditis and increased fibrosis values, along with an earlier onset of ventricular dysfunction. The T. cruzi chronically infected Syrian hamster develops a cardiomyopathy which resembles human Chagas' disease cardiomyopathy, and might be an adequate tool to investigate pathogenic mechanisms of this disease and to search for novel therapeutic strategies.

Electrocardiographic ventricular repolarization parameters in chronic Chagas' disease as predictors of asymptomatic left ventricular systolic dysfunction

Electrocardiographic repolarization parameters are potential markers of arrhythmogenic risk and have not been evaluated in Chagas' disease. The aim of this report was to investigate their associations with LV systolic function assessed by two-dimensional echocardiography. In a cross-sectional study involving 738 adult outpatients in the chronic phase of Chagas' disease, maximal QTc and T wave peak-to-end (TpTe) intervals, and QT, QTapex (QTa), IT and TpTe interval dispersions, and variation coefficients were measured and calculated from 12-lead standard ECGs. Clinical, radiological, ECG, and echocardiographic data were recorded. In bivariate statistical analysis, all repolarization parameters were significantly increased in patients with moderate or severe LV systolic dysfunction, and these patients showed more clinical, radiologic, and ECG abnormalities. Receiver operating characteristic curve analysis demonstrated that isolatedly QTd had the best predictive performance for LV dysfunction, with an 80% specificity and 67% sensitivity for values >60 ms in the subgroup of chagasic patients with abnormal ECGs and no heart failure. Multivariate logistic regression selected, as the best predictive model for LV dysfunction in this subgroup of patients, the presence of cardiomegaly on chest X ray (OR 14.06, 95% CI, 5.54-35.71), QTd >60 ms (OR 9.35, 95% CI, 4.01-21.81), male gender (OR 7.70, 95% CI, 2.98-19.91) and the presence of frequent premature ventricular contractions (PVCs) on ECG (OR 4.06, 95% CI, 1.65-9.97). This model showed 90% specificity and 71% sensitivity. In conclusion, QTd was associated to LV systolic function and could be used to predict asymptomatic dysfunction in chronic Chagas' disease. The presence of cardiomegaly, frequent PVCs, and male sex refined LV function stratification in these patients.

Increased plasma levels of tumor necrosis factor-alpha in asymptomatic/"indeterminate" and Chagas disease cardiomyopathy patients

We compared plasma tumor necrosis factor-alpha (TNF-alpha) levels among asymptomatic/"indeterminate" Chagas disease patients (ASY) and patients across the clinical spectrum of chronic Chagas disease cardiomyopathy (CCC). Idiopathic dilated cardiomyopathy (DCM) patients and normal controls (NC) were included as controls. ASY Chagas disease patients had significantly higher plasma TNF-alpha levels than NC. TNF-alpha levels among severe CCC patients with significant left ventricular (LV) dysfunction were similar to those of DCM patients, showing average 2-fold higher levels than CCC patients without LV dysfunction and ASY patients, and 8-fold higher levels than NC. In Chagas disease, chronic TNF-a production prior to heart failure may play a role in CCC progression.

Brain natriuretic peptide and left ventricular dysfunction in Chagas' disease

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.

A narrow QRS does not predict a normal left ventricular function in Chagas' disease

Left ventricular (LV) systolic dysfunction is a major prognostic determinant in Chagas' disease (ChD), a potentially fatal disorder which affects nearly 20 million individuals in Latin America. Therefore, reliable screening methods are needed to identify patients in need of a detailed evaluation of LV function. Since previous reports have suggested that a prolonged QRS duration may be an accurate predictor of LV dysfunction, the relationship between QRS duration and LV function was evaluated in ChD patients, in order to determine whether a narrow QRS on surface electrocardiogram (ECG) predicts a normal LV function. Ninety-eight patients with ChD and no other cardiac or systemic illness were underwent standard 12-lead ECG and Doppler echocardiogram (echo) examination. An investigator (blinded to the echo data) measured manually the QRS duration. LV dysfunction was defined by the presence of LV dilatation (LV diastolic dimension > 55 mm), depressed LV ejection fraction (LVEF < 0.50), segmental contractile abnormalities (SCA) or LV aneurysm. QRS duration was significantly correlated with LV diastolic dimension (r = 0.44, P = 0.000) and LVEF (r = 0.24, P = 0.016). A significant percentage of patients with QRS < 100 ms had abnormal systolic LV parameters, including LV dilatation (8.1%), reduced EF (10.2%), SCA (42.8%) and LV aneurysm (14.2%). A narrow QRS does not exclude the presence of significant global and segmental LV dysfunction in ChD patients. Since these abnormalities have prognostic and therapeutic implications, further evaluation of LV systolic performance is desirable in such patients.

Maximal functional capacity in patients with Chagas' cardiomyopathy without congestive heart failure

BACKGROUND

Chagas' disease is a known dilated form of cardiomyopathy. However, a great number of patients, although showing electrocardiographic (ECG) well-recognized changes, maintain normal ventricular chamber dimensions and are asymptomatic. The aim of the present study was to objectively characterize functional capacity in asymptomatic patients with Chagas' disease and normal left ventricular function.

METHODS AND RESULTS

Eighteen asymptomatic male patients with Chagas' disease, aged 33+/-6 years, were selected for the study. All showed ECG changes typical of the disease, as well as left ventricular fractional shortening (LVFS) greater than 0.30 on M-mode 2-dimensionally guided echocardiography. Twenty sedentary normal male patients, aged 29+/-6 years, served as controls. Both groups were submitted to ergoespirometry testing for assessment of exercise functional capacity. Patients with Chagas' disease, when compared with controls, showed lower (P < .001) maximal O2 consumption (VO2max, 24.3+/-4.2 v 37.0+/-5.4 mL x kg(-1) x min(-1) respectively); O2 pulse rate (PO2max, 10.5+/-1.4 v 15.1+/-2.5 mL/beat, respectively); maximal ventilation (VEmax, 50.1+/-13.5 v 113.0+/-17.6 L x min(-1), respectively); anaerobic threshold of maximal O2 consumption (VO2-AT, 15.8+/-3.6 v 24.6+/-4.7 mL x kg(-1) x min(-1), respectively); and maximal heart rate (HRmax, 154+/-21 v 186+/-7 beat x min(-1), respectively).

CONCLUSIONS

Asymptomatic patients with Chagas' disease, although presenting normal left ventricular systolic function at rest, display a substantial impairment of exercise functional capacity.

Cardiac afferents and neurohormonal activation in congestive heart failure

Cardiac chambers have afferent connections to the brainstem and to the spinal cord. Vagal afferents mediate depressor responses and become activated by volume expansion, increased myocardial contractility and atrial natriuretic factor. Sympathetic afferents, on the contrary, are activated by metabolic mediators, myocardial ischemia and cardiac enlargement. These opposite behaviors may lead to activation or suppression of the sympathetic nervous system and of the renin-angiotensin-aldosterone system. As cardiac diseases progress, the heart dilates, plasma norepinephrine increases, atrial natriuretic factor is released and the renin-angiotensin-aldosterone system is suppressed to maintain water and sodium excretion. This dissociation of the neurohormonal profile of cardiac patients, may be explained by coactivation of sympathetic afferents, by cardiac dilatation, and of vagal afferents by atrial natriuretic factor. In more advanced stages, atrial natriuretic factor suppression of the renin-angiotensin-aldosterone system is overridden by overt sympathetic activation and sodium and water retention ensues. Digitalis, angiotensin-converting enzyme inhibitors and beta-blockers selectively decrease cardiac adrenergic drive. A common mechanism of action, to all three groups of drugs, would be attenuation of sympathetic afferents and partial normalization of vagal afferents. Consequently, heart size and cardiac afferents emerge as the key factors to understand the pathophysiology and treatment of the syndrome of congestive heart failure.

Relation between interstitial myocardial collagen and the degree of clinical impairment in Chagas' disease

Cardiac performance is negatively associated with interstitial collagen in Chagas' cardiomyopathy. The magnitude of dysfunction is related to the degree of collagen, and this association seems to exhibit a threshold above it if definite cardiac deterioration occurs.

Chagas' heart disease and the autonomic nervous system

The autonomic nervous system is abnormal in patients with advanced Chagas' heart disease. Most researchers consider these autonomic abnormalities as primary, specific and irreversible. However, when and why these abnormalities appear in the natural history of Chagas' disease, is still the subject of intense controversy. Recent morphological and functional studies strongly suggest that the sympathetic and the parasympathetic abnormalities are preceded by myocardial damage and left ventricular dysfunction. Moreover, chagasic patients with cardiac failure benefit from drugs which antagonize neurohumoral activation. Consequently, the abnormalities of the autonomic nervous system of chagasic patients are very likely secondary and partially reversible.

Echocardiographic analysis of regional and global left ventricular shape in Chagas' cardiomyopathy

Chagas' heart disease is a common form of cardiomyopathy in Latin America and an important cause of cardiac morbidity and mortality there. Left ventricular (LV) apical aneurysm and LV dysfunction are frequent findings in Chagas' cardiomyopathy. Because cardiac shape has important implications for LV function, we sought to characterize regional and global changes in LV geometry in Chagas' heart disease. Quantitative shape analysis was performed on 2-dimensional echocardiograms from 43 patients with Chagas' cardiomyopathy. Regional shape was quantitated by measuring endocardial curvature and global shape was evaluated by Fourier shape analysis of the endocardial contour. Data from 22 age- and sex-matched normal test subjects were used for comparison. Regional shape analysis demonstrated decreased apical curvature (consistent with blunting of normal apical shape) in the group with Chagas' disease compared with controls (apical 2-chamber view: 19 +/- 1 vs 24 +/- 1 [p = 0.0039] at end-diastole and 20 +/- 2 vs 29 +/- 3 [p = 0.0019] at end-systole). Fourier shape power index was decreased in the Chagas' group, consistent with a more spherical ventricle (apical 2-chamber view: 9 +/- 1 vs 17 +/- 2 [p <0.0001] at end-diastole and 12 +/- 1 vs 35 +/- 3 [p <0.0001] at end-systole). Shape changes among the population with Chagas' disease were further evaluated in those with end-diastolic volumes equal to or greater than the median for the group (104 ml) and those < 104 ml. Global shape did not differ between patients with dilated ventricles and those with relatively nondilated ventricles. Diastolic Fourier shape power index = 8 +/- 2 in dilated ventricles compared with 9 +/- 5 in nondilated ventricles (p = 0.53); systolic Fourier shape power index = 10 +/- 2 in dilated versus 14 +/- 2 in nondilated ventricles (p = 0.15) (apical 2-chamber view). In Chagas' cardiomyopathy, LV apical deformation results in disruption of the optimal global prolate-ellipsoid shape, even in patients with relatively preserved LV volumes.

[Indeterminate form of Chagas disease: considerations about diagnosis and prognosis]

The indeterminate form of Chagas' disease is defined by the absence of clinical, radiological and electrocardiographic manifestations of cardiac or digestive involvement in Trypanosoma cruzi chronic infected persons. When submitted to advanced cardiovascular tests, these patients may present significant abnormalities. However, the indeterminate form concept was reaffirmed as valid, since diagnostic criteria are simple and prognosis is benignant. In clinical practice, diagnostic difficulties are frequent, related to subjectivity and uncertain meaning of clinical, electrocardiographic and radiological findings. Moreover, indeterminate form prognosis is not equally good: after five to 10 years, a third of patients will have cardiopathy. Sudden death, a rare complication, may be the first manifestation of Chagas' disease. It is necessary to reappraise indeterminate form concept, redefining diagnostic criteria and therapeutic management. Clinical and noninvasive evaluation may allow individual risk stratification; therapeutic interventions may be beneficial in high risk groups. Since etiologic treatment may prevent cardiopathy, its role in indeterminate form management must be reassessed.

Echocardiographic and Clinical Predictors of Mortality in Chronic Chagas' Disease

BACKGROUND: In a prospective epidemiological study of chronic Chagas' disease, several clinical and echocardiographic variables were analyzed as predictors of mortality. METHODS: Among 960 subjects seropositive for Chagas' disease who were examined between June 1981 and June 1992, 283 had echocardiograms. RESULTS: During a mean follow-up period of 48.3 +/- 36.4 months (range, 1-156 months), 108 subjects died. Echocardiographic end-diastolic and -systolic left ventricular internal dimensions, fractional shortening, radius-to-thickness ratio, left ventricular mass, mitral E-point septal separation, and 17 other nonechocardiographic variables were predictors of death on univariate analysis (P < 0.001 for each). On stepwise multiple regression analysis of 215 subjects, significant risk covariates in a Cox model analysis were clinical group (P < 0.0001), M-mode echocardiographic E-point septal separation of 22 mm (P = 0.003), presence of first- or second-degree heart block (P = 0.003), chest radiologic cardiothoracic ratio >/= 0.55 (P = 0.012), presence of electrocardiographic ST segment elevation on precordial leads (P = 0.014), age >/= 56 years (P = 0.028), and presence of right bundle-branch block (P = 0.045). Patients with an apical aneurysm on two-dimensional echocardiography had an increased mortality (Chi-square = 11.5, P < 0.001). CONCLUSIONS: Echocardiography is a valuable tool to assess the risk of death in prospective studies on chronic Chagas' heart disease.