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

Prognostic Value of Tpeak-Tend Interval in Early Diagnosis of Duchenne Muscular Dystrophy Cardiomyopathy

The most common cause of death in patients with Duchenne muscular dystrophy (DMD) is cardiomyopathy. Our aim was to investigate the relationship between the Tpeak-Tend (Tp-e) interval and the premature ventricular contraction (PVC) burden and therefore early arrhythmic risk and cardiac involvement in DMD patients. Twenty-five patients with DMD followed by pediatric cardiology were included in the study. Those with a frequency of <1% PVC in the 24 h Holter were assigned to Group 1 (n = 15), and those with >1% were assigned to Group 2 (n = 10). Comparisons were made with healthy controls (n = 27). Left ventricular ejection fraction (LVEF) was lowest in Group 2 and highest in the control group (p < 0.001). LV end-diastolic diameter was greater in Group 2 than in Group 1 and the control group (p = 0.005). Pro-BNP and troponin levels were higher in Group 1 and Group 2 than in the control group (p = 0.001 and p < 0.001, respectively). Tp-e interval was longer in Group 2 compared to Group 1 and the control group (p < 0.001). The LVEF (OR 0.879, 95% CI 0.812-0.953; p = 0.002) and Tp-e interval (OR 1.181, 95% CI 1.047-1.332; p = 0.007) were independent predictors of PVC/24 h frequency of >1%. A Tp-e interval > 71.65 ms predicts PVC > 1%, with a sensitivity of 80% and a specificity of 90% (AUC = 0.842, 95% CI (0.663-1.000), p = 0.001). Determination of Tp-e prolongation from ECG data may help in the determination of cardiac involvement and early diagnosis of arrhythmic risk in DMD.

Electrocardiogram in Chagas disease

Since the initial descriptions of Chagas cardiomyopathy (ChCM), the electrocardiography has played a key role in patient evaluations. The diagnostic criterion of chronic ChCM is the presence of characteristic electrocardiographic (ECG) abnormalities in seropositive individuals, regardless of the presence of symptoms. However, these ECG abnormalities are rarely specific to ChCM and, particularly among the elderly, can be caused by other simultaneous cardiomyopathies. ECG abnormalities can predict the occurrence of heart failure, stroke, and even death. Nevertheless, most prognostic studies have included Chagas disease (ChD) populations and, not exclusively, ChCM. Thus, more studies are required to evaluate the efficacy of ECG in predicting reliable prognoses in established chronic ChCM. This review exclusively discusses the role of the 12-lead ECG in the clinical evaluation of chronic ChD.

Chagas Cardiomyopathy: Usefulness of EKG and Echocardiogram in a Non-Endemic Country

BACKGROUND

Chagas disease (CD) is a major cause of cardiomyopathy in Latin America, and migration movements have now spread the disease worldwide. However, data regarding Chagas cardiomyopathy (CC) and the usefulness of echocardiography in non endemic countries are still scarce.

METHODS AND RESULTS

We selected 485 patients in the chronic phase of CD from two Spanish settings. Data from physical examination, electrocardiogram (EKG), x-ray, and two dimensional transthoracic echocardiogram were recorded. Trypanosoma cruzi DNA was assessed by PCR in peripheral blood. Patients were stratified according to the Kuschnir classification and a combination of echocardiogram and electrocardiogram findings. Patients mainly came from Bolivia (459; 94.6%). One hundred and forty three patients (31.5%) had at least one electrocardiogram abnormality. Twenty seven patients (5.3%) had an abnormal echocardiography. Patients with abnormal echocardiography were older (47 (IQR 38-57) years vs 41 (IQR 38-57) years); p = 0.019) and there was a greater proportion of males (66.7% vs 29.7%); p<0.001). Among echocardiographic variables, diastolic dysfunction was associated with poor cardiac status. In the multivariate analysis, abnormal EKG and gender were associated with abnormal echocardiography. Echocardiography may be spared for males under 30 and females under 45 years old with normal EKG as the likelihood of having an abnormal echocardiography is minimal. Association between T. cruzi DNA in the peripheral blood and cardiac involvement was not observed.

CONCLUSION

CC rates in the studied population are low. Age and sex are important determinants for the development of CC, and with the EKG should guide echocardiogram performance.

MicroRNA Transcriptome Profiling in Heart of Trypanosoma cruzi-Infected Mice: Parasitological and Cardiological Outcomes

Chagas disease is caused by the parasite Trypanosoma cruzi, and it begins with a short acute phase characterized by high parasitemia followed by a life-long chronic phase with scarce parasitism. Cardiac involvement is the most prominent manifestation, as 30% of infected subjects will develop abnormal ventricular repolarization with myocarditis, fibrosis and cardiomyocyte hypertrophy by undefined mechanisms. Nevertheless, follow-up studies in chagasic patients, as well as studies with murine models, suggest that the intensity of clinical symptoms and pathophysiological events that occur during the acute phase of disease are associated with the severity of cardiac disease observed during the chronic phase. In the present study we investigated the role of microRNAs (miRNAs) in the disease progression in response to T. cruzi infection, as alterations in miRNA levels are known to be associated with many cardiovascular disorders. We screened 641 rodent miRNAs in heart samples of mice during an acute infection with the Colombiana T.cruzi strain and identified multiple miRNAs significantly altered upon infection. Seventeen miRNAs were found significantly deregulated in all three analyzed time points post infection. Among these, six miRNAs had their expression correlated with clinical parameters relevant to the disease, such as parasitemia and maximal heart rate-corrected QT (QTc) interval. Computational analyses identified that the gene targets for these six miRNAs were involved in networks and signaling pathways related to increased ventricular depolarization and repolarization times, important factors for QTc interval prolongation. The data presented here will guide further studies about the contribution of microRNAs to Chagas heart disease pathogenesis.

Chagas’ disease is caused by the protozoan parasite Trypanosoma cruzi and affects 8 million individuals worldwide. The life-long infection begins with a short acute phase, which is associated to parasites circulating in the bloodstream, tissue parasitism, and various signs and symptoms including those related to myocarditis. After resolution of the acute phase, about 30% of those chronically infected will develop abnormal ventricular repolarization with hypertrophy, myocarditis and fibrosis by yet undefined mechanisms. MicroRNAs play a key role in silencing gene expression and are essential elements of the physiology and pathophysiology of the cardiovascular system. Here we describe for the first time the effect of acute T. cruzi infection on host miRNA expression by screening 641 rodent miRNAs in heart samples. A number of miRNAs have significantly altered expression upon infection and several of them correlate with T. cruzi parasitism and electrocardiographic changes. Pathway analysis results suggest that these dysregulated miRNAs can potentially affect gene networks and signaling pathways related to increased ventricular depolarization and repolarization times. Our study provides new insights on miRNA regulation of genes relevant to parasitological and cardiological outcomes.

Electrocardiographic abnormalities in Trypanosoma cruzi seropositive and seronegative former blood donors

BACKGROUND

Blood donor screening leads to large numbers of new diagnoses of Trypanosoma cruzi infection, with most donors in the asymptomatic chronic indeterminate form. Information on electrocardiogram (ECG) findings in infected blood donors is lacking and may help in counseling and recognizing those with more severe disease.

OBJECTIVES

To assess the frequency of ECG abnormalities in T.cruzi seropositive relative to seronegative blood donors, and to recognize ECG abnormalities associated with left ventricular dysfunction.

METHODS

The study retrospectively enrolled 499 seropositive blood donors in São Paulo and Montes Claros, Brazil, and 483 seronegative control donors matched by site, gender, age, and year of blood donation. All subjects underwent a health clinical evaluation, ECG, and echocardiogram (Echo). ECG and Echo were reviewed blindly by centralized reading centers. Left ventricular (LV) dysfunction was defined as LV ejection fraction (EF)<0.50%.

RESULTS

Right bundle branch block and left anterior fascicular block, isolated or in association, were more frequently found in seropositive cases (p<0.0001). Both QRS and QTc duration were associated with LVEF values (correlation coefficients -0.159,p<0.0003, and -0.142,p = 0.002) and showed a moderate accuracy in the detection of reduced LVEF (area under the ROC curve: 0.778 and 0.790, both p<0.0001). Several ECG abnormalities were more commonly found in seropositive donors with depressed LVEF, including rhythm disorders (frequent supraventricular ectopic beats, atrial fibrillation or flutter and pacemaker), intraventricular blocks (right bundle branch block and left anterior fascicular block) and ischemic abnormalities (possible old myocardial infarction and major and minor ST abnormalities). ECG was sensitive (92%) for recognition of seropositive donors with depressed LVEF and had a high negative predictive value (99%) for ruling out LV dysfunction.

CONCLUSIONS

ECG abnormalities are more frequent in seropositive than in seronegative blood donors. Several ECG abnormalities may help the recognition of seropositive cases with reduced LVEF who warrant careful follow-up and treatment.

Prognostic value of exercise-induced ventricular arrhythmia in Chagas' heart disease

OBJECTIVE

To determine the prevalence and the prognostic value of exercise-induced ventricular arrhythmia (EIVA) in chronic Chagas' heart disease.

STUDY DESIGN AND SETTING

An open prospective cohort of 130 clinically stable patients at a University Hospital outpatient unit in Rio de Janeiro, Brazil, was followed up at scheduled clinical visits from 1990 through 2007. The endpoint was total cardiovascular mortality. Survival curves (Kaplan-Meier) and a multivariate Cox proportional hazard model were adjusted to determine the association between EIVA and mortality.

RESULTS

The median duration of follow-up was 9.9 years (range, 132 days to 17 years). EIVA prevalence was 43.1% (95% CI: 34.5-51.7). Thirty-three cardiovascular deaths (25.4%) occurred. The hazard ratio of EIVA for cardiovascular death, after adjustment for age, was 1.84 (P = 0.09). An interaction was found between EIVA and cardiomegaly on x-ray. In the group with cardiomegaly, the hazard of dying was four times greater in the presence of EIVA (P for interaction = 0.05).

CONCLUSION

In clinically stable chagasic subjects with cardiomegaly, EIVA is a clinically significant marker of total cardiovascular mortality and may be a useful risk stratification tool in this population.

Abnormal cardiac repolarization in anabolic androgenic steroid users carrying out submaximal exercise testing

1. The aim of the present study was to investigate the cardiovascular effects of anabolic androgenic steroid (AAS) abuse by comparing the electrocardiographic parameters before and after submaximal exercise between AAS users and non-AAS users. 2. A total of 22 men who regularly engaged in both resistance and aerobic exercise at fitness academies volunteered for the study (control group: n = 11, age 25 ± 4 years; AAS group: n = 11, age 27 ± 5 years). All subjects were submitted to submaximal exercise testing using an Astrand-Rhyming protocol. Heart rate and electrocardiography parameters were measured at rest and at the third minute of the post-exercise recovery time. 3. AAS users presented higher QTc and QTd at rest (10% and 55%, respectively) and at the post-exercise period (17% and 43%, respectively), compared with control subjects. The maximal and minimum QTc interval of the AAS group was significantly prolonged at the post-exercise period (12% and 15%, respectively). The haemodynamic parameters were similar in both groups (P > 0.05). The AAS group showed a lower heart rate recovery at the first minute after the test (P = 0.0001), and a higher exertion score (P < 0.0001) at a lower workload, compared with the control group. 4. Our results show that the QTc interval and dispersion are increased in individuals who abuse AAS, suggesting the presence of ventricular repolarization abnormalities that could potentially increase the risk of cardiac arrhythmias and sudden cardiac death.

Cardiac involvement in African and American trypanosomiasis

American trypanosomiasis (Chagas disease) and human African trypanosomiasis (HAT; sleeping sickness) are both caused by single-celled flagellates that are transmitted by arthropods. Cardiac problems are the main cause of morbidity in chronic Chagas disease, but neurological problems dominate in HAT. Physicians need to be aware of Chagas disease and HAT in patients living in or returning from endemic regions, even if they left those regions long ago. Chagas heart disease has to be taken into account in the differential diagnosis of cardiomyopathy, primarily in patients with pathological electrocardiographic (ECG) findings, such as right bundle branch block or left anterior hemiblock, with segmental wall motion abnormalities or aneurysms on echocardiography, and in young patients with stroke in the absence of arterial hypertension. In HAT patients, cardiac involvement as seen by ECG alterations, such as repolarisation changes and low voltage, is frequent. HAT cardiopathy in general is benign and does not cause relevant congestive heart failure and subsides with treatment. We review the differences between the American and African trypanosomiasis with the main focus on the heart.

Echocardiography in Chagas heart disease

BACKGROUND

Chagas heart disease is a frequent cause of morbidity and mortality in Latin America. Echocardiography provides useful diagnostic and prognostic information and is an important tool in the management of patients with Chagas disease.

METHODS AND RESULTS

A search for relevant publications was obtained from MEDLINE, LILACS, and SCIELO sources. Acute Chagas myocarditis is a rare disorder in which pericardial effusion is frequent. Echocardiography may exclude pericardial tamponade in case of heart failure. Chronic Chagas cardiomyopathy evolves for several decades after the infection. Epidemiological history, positive serology, and suggestive clinical and ECG abnormalities establish the diagnosis. About three quarters of chronic Chagas cardiomyopathy subjects remain asymptomatic with normal (indeterminate form) or abnormal ECGs. Early Doppler abnormalities includes prolongation of isovolumic contraction and relaxation times. Systolic function frequently is normal, but dysfunction may be elicited by stress tests. Half or more of symptomatic patients have a left ventricular apical aneurysm and other segmental contractile abnormalities similar to those seen in coronary heart disease. The dilated nonsegmental form is indistinguishable from dilated cardiomyopathy. Results from univariate and multivariate Cox survival analyses indicate that impaired systolic function and increased ventricular dimensions have significant value in predicting cardiac morbidity and mortality. Cardiac ultrasound commonly is used in the follow-up of patients and in the assessment of various therapeutic modalities.

CONCLUSIONS

Echocardiographic and Doppler techniques provide useful structural and functional information in the detection of early myocardial damage, risk assessment of prognosis, disease progression, and management of patients with Chagas disease.

Human antibodies with muscarinic activity modulate ventricular repolarization: basis for electrical disturbance

INTRODUCTION

In chronic chagasic patients sudden death has been reported when QT interval dispersion is increased and antibodies with muscarinic-like activity have been demonstrated to trigger arrhythmias. The aims were to investigate, in vivo and in vitro, relation between these antibodies and heterogeneity of ventricular repolarization and to identify predictors of cardiac death in chronic chagasic patients.

METHODS AND RESULTS

Clinical, electrocardiograph and echocardiograph variables from 32 chronic chagasic patients with moderate to severe left ventricular dysfunction, followed-up for 10 years were analyzed. Sera from chronic chagasic patients with or without muscarinic activity were tested in isolated rabbit hearts to study ventricular repolarization. Stepwise multivariate logistic analysis was applied to identify independent predictors of cardiac death. QT interval dispersion of patients with muscarinic activity (75.9+/-5.5 ms) was larger than that of patients without muscarinic activity (51.3+/-4.0 ms, p<0.001). Maximum uncorrected and corrected QT intervals were not significantly different between groups of patients. Sera from patients with muscarinic activity significantly and reversibly increased QT interval in isolated rabbit hearts (p=0.002). This effect was abolished in the presence of the muscarinic antagonist atropine. Multivariate analysis identified maximum corrected QT intervals and left ventricular end diastolic index as independent predictors of cardiac death (p=0.03 and p=0.02, respectively).

CONCLUSIONS

Sera with muscarinic activity from chagasic patients have a strong contribution to evoke ventricular repolarization rhythm disorder. In these patients, ventricular repolarization heterogeneity is increased significantly. In vitro, muscarinic sera reversibly increased repolarization duration. Maximum corrected QT intervals and left ventricular end diastolic index are independent predictors of cardiac death.

Brain natriuretic peptide based strategy to detect left ventricular dysfunction in Chagas disease: A comparison with the conventional approach

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 <or=0.40) was 9.1% in the sample 1. The conventional strategy recognized all patients with LVd (sensitivity: 100%, 95% CI: 79.6-100% and negative predictive value -PV 100%, 92.1-100%), but with low specificity (30%, 95% CI: 23.2-37.8) and +PV (12.5%, 95% IC: I7.7-19.6). The BNP/ECG strategy showed significantly better specificity (96.0%, 95% CI: 91.5-98.2, p < 0.001) and +PV (66.7%, 95% CI: 43.7-83.7, p < 0.001), and non-significantly lower sensitivity (80.0%, 95% CI: 54.8-93.0, p = 0.25) and -PV (98.0%,95% CI: 94.2-99.3, p = 0.08). Overall accuracy was improved with the new strategy. (94.5%,95% CI: 90.0-97.1 x 36.4%, 95% CI: 29.4-43.9, p < 0.001). Similar results were obtained for the sample 2.

CONCLUSIONS

The BNP-based strategy was more accurate than the conventional approach in the detection of LVd in ChD patients and should be considered as a valid option.

QT interval dispersion in patients with chronic heart failure secondary to Chagas' cardiomyopathy: correlation with clinical variables of prognostic significance

BACKGROUND

QTc interval dispersion has rarely been studied in patients with chronic heart failure (CHF) secondary to Chagas' cardiomyopathy. One study has demonstrated an association between QT interval dispersion and sudden cardiac death. No data exist regarding the association of clinical variables and QT interval dispersion in patients with this condition.

METHODS

Sixty three patients with CHF due to Chagas' cardiomyopathy, 34 Chagas' disease patients with no systolic dysfunction on echocardiography, and 36 individuals with no previous cardiac history, matched by sex and a 10-year age interval, were included in the investigation. The QTc interval dispersion was defined as the difference between maximum and minimum QTc.

RESULTS

The mean QTc interval dispersion was 74+/-30.3 ms in surviving and 87+/-30.6 ms in nonsurviving patients (P=.13). Mean QTc dispersion was 95.20+/-28.46 ms in patients who died from pump failure, 73.33+/-29.61 ms in patients who died suddenly, and 74.46+/-30.27 in survivors (P=.07). Mean QTc dispersion value was higher in patients in the Class III or IV (P=.01).). Mean QTc interval dispersion was 67.2+/-22.7 ms in patients with and 85.5+/-33.5 ms in patients without premature ventricular contractions (P=.01), and 67.5+/-29.8 ms in patients with and 84.7+/-31.8 ms in patients without left ventricular apical aneurysm (P=.03). A correlation could be observed in QTc interval dispersion and left atrium dimension (r=.32; P=.009) Thus, QTc interval dispersion is associated to some prognostic indicators in patients with CHF secondary to Chagas' cardiomyopathy.

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.

Prognostic value of QT interval parameters for mortality risk stratification in Chagas' disease: results of a long-term follow-up study

BACKGROUND

QT interval parameters are potential prognostic markers of arrhythmogenicity risk and cardiovascular mortality and have never been evaluated in Chagas' disease.

METHODS AND RESULTS

Outpatients (738) in the chronic phase of Chagas' disease were enrolled in a long-term follow-up study. Maximal heart rate-corrected QT (QTc) and T-wave peak-to-end (TpTe) intervals and QRS, QT, JT, QTapex, and TpTe dispersions and variation coefficients were measured manually and calculated from 12-lead ECGs obtained on admission. Clinical, radiological, and 2-dimensional echocardiographic data were also recorded. Primary end points were all-cause, Chagas' disease-related, and sudden cardiac mortalities. During a follow-up of 58+/-39 months, 62 patients died, 54 of Chagas' disease-related causes and 40 suddenly. Multivariate Cox survival analysis revealed that the QT-interval dispersion (QTd) (hazard ratio, 1.45; 95% confidence interval, 1.29 to 1.63; P<0.001, for 10-ms increments) and left ventricular (LV) end-systolic dimension (hazard ratio, 1.36; 95% confidence interval, 1.21 to 1.53; P<0.001, for 5-mm increments) were the strongest independent predictors for all end points. The maximum QTc interval (QTcmax) could substitute for QTd with a worse predictive performance. Other predictors were heart rate, presence of pathological Q waves, frequent premature ventricular contractions (PVCs), and isolated left anterior fascicular block (LAFB) on the ECGs. Kaplan-Meier survival curves demonstrated that a QTd > or =65 ms or a QTcmax > or =465 ms1/2 discriminated the 2 groups with significantly different prognoses.

CONCLUSIONS

Electrocardiographic QTd and echocardiographic LV end-systolic dimension were the most important mortality predictors in patients with Chagas' disease. Heart rate, the presence on ECG of pathological Q waves, frequent PVCs, and isolated LAFB refined the mortality risk stratification.