Nov 7, 2014

Marcio Barros, MD, PhD, visits CCI for a collaboration study


Marcio Barros, MD, PhD, Laboratory Head of Echocardiography at Hospital Mater Dei, Brasil, recently visited CCI in a joint collaboration study.

The study focuses on the use of mechanical dispersion assessed by two-dimensional strain echocardiography in the evaluation of Chagas disease ICD patients comparing with Chagas disease patients without ICD. The purpose of this study has been to evaluate this new technique in the assessment of potential predictors from malignant arrhythmias. 

Posted by: Anonymous

Text by Marcio Barros.

Chagas disease (DCH) remains a leading medical-social problem in Latin America, affecting eight to ten million people, with high economic impact, morbidity and mortality. The clinical course of the disease is extremely variable and, although many individuals remain asymptomatic for long periods, approximately one third of infected patients develop life-threatening heart disease, including malignant ventricular arrhythmias and heart failure.

Sudden death is one of the characteristic phenomena of DCH and is responsible for more than 50% mortality in patients with heart failure. Electrophysiological mechanisms most frequently involved with sudden death in Chagas disease are represented by ventricular tachycardia and ventricular fibrillation. With the development of therapeutic strategies for the prevention of death from ventricular fibrillation, especially with ICD, there is considerable interest in developing strategies that predict progression to death and, in particular, sudden death, in Chd.

Although there are no studies of secondary prevention designed specifically for the population of patients with Chagas disease, secondary prevention are currently well accepted for this group of patients, taking into account the results of studies conducted in other population. However, ICD implantation for primary prevention in patients with Chagas heart disease will remains a controversial matter. The indiscriminate use of the ICD is not cost-effective. For all that, more precise risk stratification is needed to identify patients at high risk of sudden death. Furthermore, ICD implantation is an invasive procedure with risks (inappropriate shocks, pro-arrhythmias, per and post-operative complications, problems with the electrodes, infection) and can lead to depression, anxiety and poor quality of life.

Although several clinical features such as age and NYHA class were assessed as possible risk factors for the development of fatal arrhythmias, the sensitivity and specificity of any single test to predict fatality are limited. There are several studies on markers of high risk of death in ChD, although almost all of them used the outcome was all-cause mortality and not the presence of arrhythmic death. Thus, although it is recognized that left ventricular dysfunction is a strong predictor of the risk general and arrhythmic death in ChD, the simple presence of depressed ejection fraction (LVEF) is not sensitive or specific enough to stratify the risk of sudden death. Most patients with ICD for secondary prevention (which has thus had a potentially fatal arrhythmic event) show LVEF> 30%. No sustained ventricular tachycardia on Holter monitoring or exercise testing,  late potentials in High  ECG resolution, ventricular tachycardia induced the, QT prolongation or an increase in their dispersion, and, more recently, the amplitude value of the T wave  and high levels of BNP  are some of the variables related to increased risk of death. Although each of these tests have prognostic value in overall mortality, we do not know whether they are able to predict, with adequate sensitivity and specificity, who have malignant arrhythmias and sudden death, with potential candidates for ICD implantation. Thus, when specifically evaluating ICD implantation new strategies for risk stratification are important and need to be developed and tested.

In collaboration with Oslo University and under Professor Thor Edvardsen supervision, we developed a study with the main purpose to use mechanical dispersion assessed by two-dimensional strain echocardiography in the evaluation of Chagas disease ICD patients comparing with chagasic patients without ICD, in order to evaluate this new technique in the assessment of potential predictor from malignant arrhythmias.

From left: Kristina Haugaa, Marcio Barros, Ida Skrinde Leren, Thor Edvardsen

Center for Cardiological Innovation