Chagas Heart Disease an Emerging Concern in the United States
As an echocardiographer at the Medstar Washington Hospital in Washington, DC, Rachel Marcus, MD, has become skilled at identifying a killer that is best known for stalking victims in rural Latin America—Chagas disease.
Chagas disease is caused by a parasite called Trypanosoma cruzi, which most often is transmitted to humans by insects called kissing bugs. The disease is prevalent in poor Latin American communities with inadequate housing, where the insects bite humans at night. The insects then infect the person’s wound with their parasite-laden feces. It also can be spread from mother to child or through blood transfusions or transplants.
The disease is becoming a growing public health concern in the United States, particularly in communities with large populations of immigrants from Latin America. In fact, the United States now has the seventh highest prevalence of Chagas infections in the Western Hemisphere, with >300 000 infected individuals estimated to be living in the United States. Of those, an estimated 30 000 to 45 000 will go on to develop Chagas heart disease.
As a result, US cardiologists such as Marcus who serve communities with large populations of Latin American immigrants are seeing substantial numbers of patients whose cardiomyopathies were caused by Chagas. In fact, 1 in 5 of the patients with cardiomyopathy at 1 Los Angeles hospital who had lived in Latin American countries for at least a year had Chagas cardiomyopathy. The condition requires far more aggressive treatment than do other forms of cardiomyopathy, but awareness about Chagas disease and its heart-related complications among US physicians is low.
“If you don’t believe the diagnosis exists, you will never diagnose,” Marcus said. “You have to start thinking about it.”
The Washington, DC, metro area where Marcus works is home to a growing number of Latin American immigrants, the largest subgroup of which hails from El Salvador, according to data from the 2010 US Census. El Salvador has a high prevalence of T cruzi infections with about 1.3 per 100 people infected with the parasite, according to the World Health Organization. Northern Virginia is home to a large population of immigrants from Bolivia, which has the highest prevalence of Chagas in Latin America, and where >6 of every 100 people are infected with T cruzi.
By the time Marcus sees the telltale arrhythmias and other conduction abnormalities associated with the disease, her patients have been infected for 15 to 30 years. Many were infected during childhood and most were asymptomatic or had mild symptoms that went undetected for years. When symptoms finally develop, the underlying cardiac damage is typically advanced.
“Once they are at that point, there is no cure,” said Sheba Meymandi, MD, director of the Center of Excellence for Chagas Disease at Olive View-University of California-Los Angeles Medical Center.
Treatment with benznidazole, an antiparasitic treatment, can cure patients with Chagas early in the course of their infection. Once patients have progressed to develop Chagas cardiomyopathy, however, benznidazole treatment can reduce the detection of T cruzi parasites in the patient’s serum, but it does not stop cardiac decline, according to the results of the BENEFIT (Evaluation of the Use of Antiparasital Drug [Benznidazole] in the Treatment of Chronic Chagas' Disease) trial, a randomized study that enrolled 2854 patients with Chagas cardiomyopathy and followed them for 5 years.
Diagnosing Chagas disease in patients with cardiomyopathy, however, can allow cardiologists to implement the aggressive treatment regimens recommended for this subset of patients, who have 4-fold higher morbidity and mortality than do typical patients with cardiomyopathies, Meymandi noted.
“[Chagas cardiomyopathy] can act differently than other cardiomyopathies,” said Marcus.
Marcus explained that the parasites become embedded in the heart, affecting cardiac conduction, something that can be picked up on an ECG. The patients may develop slow heart rhythms as well as inflammation and scarring in the heart, she said. Patients are at risk of ventricular tachycardia, left ventricular dilation, and blood clots resulting in strokes, aneurysms, heart failure, or sudden cardiac death.
“These patients get horrific, really malignant ventricular arrhythmias,” said Meymandi.
Patients who have lived in Chagas-endemic countries, and who have conduction abnormalities and heart failure, should be screened for Chagas disease, said Meymandi. Individuals who lived in rural areas in thatched or adobe dwellings are at greatest risk, she said.
Testing patients for Chagas disease should be performed in coordination with the US Centers for Disease Control and Prevention, which can provide the 2 tests needed for a diagnosis of Chagas disease, said Marcus.
Treatment and Prevention
For patients diagnosed with Chagas cardiomyopathy, Meymandi and her colleagues use routine heart failure medication management, implantable cardiac defibrillators, and amiodarone, an antiarrhythmic that helps control the patient’s arrhythmias and, interestingly, also decreases their parasite load, she said.
“We treat these patients very, very aggressively,” Meymandi said.
Patients whose conditions worsen with this treatment regimen, and for whom resynchronization therapy fails, may be candidates for heart transplant, said Meymandi. Patients with Chagas heart disease who undergo a transplant must be carefully monitored for signs that their infection has become reactivated, Marcus asserts. Recently, Marcus had to treat a heart transplant patient who experienced a reactivation with antiparasitic medication.
Cardiologists who encounter patients with suspected Chagas cardiomyopathy should consider reaching out to a clinician experienced with diagnosing and treating the disease who can help talk them through the testing process, Marcus said. “If somebody identifies a patient who might have Chagas, absolutely reach out to us and get guidance,” she said.
Marcus, medical director of the Latin American Society of Chagas (lasocha.org), hopes to develop an inexpensive rapid test for Chagas disease that may 1 day make the process of identifying patients with Chagas heart disease easier.
The best approach to Chagas heart disease for communities with large populations of immigrants from Latin America, however, may be to try to prevent such late-stage complications by more aggressively screening for and treating infections early, said Meymandi. She and her colleagues are working to boost primary care screening of Latin American immigrants for Chagas heart disease in Los Angeles County. Preventing cases of Chagas-related heart failure may also be cost-effective, she noted.
“It’s preventive medicine at its best,” said Meymandi. “If you diagnose and treat early, you don’t have to deal with the long-term complications of Chagas.” n
© 2016 American Heart Association, Inc.
- © 2016 American Heart Association, Inc.