A simple imaging exam capable of assessing myocardial deformation during contraction has emerged as a promising tool for predicting the risk of cardiac complications in patients with chronic Chagas disease. The study, conducted by researchers at the University of São Paulo (USP) in Ribeirão Preto in partnership with researchers from Duke University and Yale (both in the United States), highlights the global longitudinal strain (GLS) index – already used in other diseases and conditions – as a sensitive and independent marker for predicting outcomes in chronic Chagas cardiomyopathy. The results were published in the journal PLOS Neglected Tropical Diseases.
Chronic Chagas cardiomyopathy is one of the primary consequences of chronic Chagas disease. Caused by the parasite Trypanosoma cruzi, the condition damages heart tissue over time, resulting in inflammation, scarring (fibrosis), and heart failure. Even after the acute phase, the infection can progress silently for decades, eventually causing serious complications, such as arrhythmia, embolism, and sudden death.
The strain technique is an advanced echocardiography method that measures GLS by tracking bright spots in cardiac images (speckle tracking). This index can identify whether the myocardium is deforming properly during systole (contraction), which is a crucial sign of cardiac tissue damage, even before fibrosis becomes evident.
"When the myocardium isn't deforming properly, this suggests fibrosis in the tissue. Therefore, although GLS doesn't directly visualize fibrosis in cardiac tissue, it predicts its presence among the heart's muscle cells [myocytes], which signals a high risk of future complications," explains Minna Moreira Dias Romano , professor at the Ribeirão Preto School of Medicine at USP.
In the study, supported by FAPESP, echocardiography tests from 77 patients with chronic Chagas disease were analyzed. The patients were followed for approximately three years. Patients were divided into three groups based on GLS values, and outcomes evaluated included death, hospitalizations, sustained ventricular tachycardia, new cases of heart failure, and cardioembolic events.
The results showed that patients with a GLS of -13.8% or greater (indicating greater compromise) had a worse prognosis, with a higher incidence of death and complications. Even after adjusting for age, sex, and left ventricular ejection fraction (the percentage of blood pumped by the left ventricle with each beat), the researchers found that GLS remained a statistically significant independent predictor of risk.
"This technique is already used in several other heart diseases, such as in cancer patients to monitor damage to the heart caused by chemotherapy, as in cases of breast cancer. Now, the study suggests that the same method can be applied to track the progression of Chagas disease, especially in places where diagnosis is rare, such as in geographic regions with a low prevalence of the disease," the researcher explained to Agência FAPESP.
Romano points out that previous studies have validated other indices for the early detection of cardiac complications resulting from Chagas disease, but have not yet proven the role of GLS as an independent prognosticator.
One of the validated methods for predicting the risk of chronic heart disease caused by Chagas disease is the Rassi score. Developed by a Brazilian researcher, the score evaluates six variables to predict the long-term prognosis of patients with Chagas disease. "It's already been validated, but it still leaves a margin of risk among intermediate cases, that is, those that aren't classified as high or low risk," says the researcher.
The most accurate method for detecting myocardial fibrosis is cardiac magnetic resonance imaging with contrast (gadolinium). However, this expensive test is not widely available and can cause patient discomfort, such as claustrophobia.
On the other hand, echocardiography using GLS is cheaper, can be repeated as many times as necessary, and can be applied on a large scale. "It's a risk marker that can be widely applied, especially in places where the diagnosis of Chagas heart disease is still rare," Romano emphasizes.
Despite the good news, there are still challenges to implementing GLS on a large scale. Although the technique is accessible, it requires technical knowledge and specialized interpretation. "The technique is more complex than conventional laboratory tests, such as biochemical assays. Even so, it represents a significant advance in risk stratification and monitoring the progression of chronic Chagas cardiomyopathy, offering healthcare professionals a powerful tool for making more accurate clinical decisions," Romano concludes.
About São Paulo Research Foundation (FAPESP)
The São Paulo Research Foundation (FAPESP) is a public institution with the mission of supporting scientific research in all fields of knowledge by awarding scholarships, fellowships and grants to investigators linked with higher education and research institutions in the State of São Paulo, Brazil. FAPESP is aware that the very best research can only be done by working with the best researchers internationally. Therefore, it has established partnerships with funding agencies, higher education, private companies, and research organizations in other countries known for the quality of their research and has been encouraging scientists funded by its grants to further develop their international collaboration. You can learn more about FAPESP at www.fapesp.br/en and visit FAPESP news agency at www.agencia.fapesp.br/en to keep updated with the latest scientific breakthroughs FAPESP helps achieve through its many programs, awards and research centers. You may also subscribe to FAPESP news agency at http://agencia.fapesp.br/subscribe .
