New US Stats on Chagas Heart Failure Show Outlook Is Grim

November 13, 2012

LOS ANGELES — New data on heart failure caused by Chagas disease paints a grim picture, with doctors at the only US center for excellence for this disease showing that sufferers have a fourfold higher mortality than those with conventional heart failure. Patients with Chagasic cardiomyopathy are also sicker than conventional heart-failure patients, with a twofold higher rate of hospitalization.

"If you have heart failure and if the etiology is Chagas, then you have a higher risk of developing complications and dying; this is a pretty awful disease," Dr Sheba Meymandi (Olive View/University of California, Los Angeles Medical Center, Sylmar) told heartwire .

Meymandi and colleagues presented their contemporary findings on the prevalence, morbidity, and mortality of Chagas disease in a US-based population in a poster at last week's American Heart Association 2012 Scientific Sessions.

"Most of our patients, when we diagnose them, have had Chagas for decades; they acquire it usually in Central or South America," she explained. "These patients usually have more ventricular arrhythmias that put them at risk for sudden death. Many of our patients will be on amiodarone and have a defibrillator fitted, but they just get shock after shock after shock, so we often have to put them on dual antiarrhythmic therapy--amiodarone and mexiletine." And in severe cases, the only option for patients is cardiac transplantation. "There is a massive increase in morbidity and mortality with the Chagasic HF patient, and this is despite very, very aggressive treatment," she observes.

One in Five HF Patients in LA County Has Chagas Disease

Meymandi explained that there is a large Latin American immigrant population living in LA County, with more than two million residents born in Chagas-endemic countries. Previous research conducted in Latin America has shown that Chagasic cardiomyopathy portends a poorer prognosis compared with both ischemic and nonischemic "run-of-the-mill" heart failure. But there are no recent data on the disease in a US-based population.

 
There is a massive increase in morbidity and mortality with the Chagasic HF patients, and this is despite very, very aggressive treatment.
 

She and her colleagues prospectively enrolled 135 patients from their county hospital who were diagnosed with nonischemic cardiomyopathy (ejection fraction <40%). The patients had no significant coronary artery disease on previous angiography or stress testing. All participants had previously resided in Latin America for at least 12 months. Serologic testing for Chagas disease was performed at enrollment by the Centers for Disease Control and Prevention (CDC).

The primary end point was all-cause mortality or heart transplant, confirmed by reviewing medical records, contacting patients' family members, and accessing Social Security databases. The secondary end point was HF-related hospitalization. Participants were followed for a median of 3.6 years.

The researchers found Chagas cardiomyopathy was a common cause of heart failure in their patient population, with an incidence approaching one in five (19%).

Death rates were more than fourfold higher for those with Chagas disease, and morbidity was double, compared with the conventional HF patients.

Outcome Summary: Unadjusted Survival and Hospitalization Rates

Outcome Chagas (n=25) No Chagas (n=110) p
Survival rates (%)     <0.0001
2 y 84 92  
4 y 54 88  
Mean survival time, mo 42 54  
Crude mortality/y (%) 13 3 <0.05
Freedom from hospitalization (%)*     0.01
2 y 66 79  
4 y 35 63  
Mean time free from hospitalization, mo 33 44  
Crude hospitalization/y (%) 51 24 <0.05

*Time to first hospitalization or last follow-up, whichever comes first

The researcher says treatment of Chagas heart disease with antiparasitic medication prior to the development of end-stage heart failure may slow or prevent its progression. Patients also get antiarrhythmics and other HF medications as required.

"All our patients get amiodarone, not only because it helps with arrhythmias--even if they don't have arrhythmias we treat them with it, because it decreases the parasite load," says Meymandi. Next will come the addition of mexiletine and other heart-failure medications and usually a defibrillator, she says. Epicardial ablation can also be useful, but this can often be performed only in those with insurance coverage, she notes. Ultimately, many people end up on the cardiac transplant list.

Chagas Disease Is the Leading Cause of Infective Myocarditis

Chagas disease, named after the Brazilian physician Dr Carlos Chagas who first described it in 1909, exists only in the Western hemisphere. It results from an infection by Trypanosoma cruzi, a protozoan parasite transmitted by the cone-nosed reduviid bug, or triatomine, also known as the "kissing" bug for its habit of biting sleeping people on the uncovered face. There are about 15 species of triatomines that can transmit T cruzi, which is usually spread via the feces of the bug into the blood when a person scratches their face after having been bitten or through contamination of food. It can also be contracted through blood transfusion, although many countries now screen for T cruzi, including the US.

Chagas disease extends from the south of Argentina to Mexico and even into the southern US, although the higher standard of living makes cases there extremely rare. The poor are at much greater risk of infection, as the reduviid bugs live in the walls of hut dwellings, common throughout the poorer areas of Central and South America. Due to the large reservoir of T cruzi, the parasite cannot be eradicated, and vector control is the most effective method of preventing Chagas disease

According to the World Health Organization (WHO), 10 million people are currently infected worldwide and 25 million are at risk; 10 000 people died from Chagas disease in 2008. The disease has three stages: an acute phase, which is a febrile illness lasting 30 to 60 days, during which the parasites can easily be detected in the blood. If the infection is left untreated, there follows an indeterminate, subclinical phase, which can last up to 10 or 15 years--most of these individuals will remain asymptomatic for decades, but each year around 3% will develop lesions of the heart or gastrointestinal tract.

Chronic cardiomyopathy is the most severe manifestation of Chagas disease, and Chagas is the leading cause of infective myocarditis, eventually affecting 20% to 30% of those with chronic-phase disease. The direct action of the parasite on the heart causes myocardial-cell destruction, and the patient develops arrhythmias and/or heart failure.

Outreach Programs Needed to Screen for Chagas in the Community

Given the dire consequences of increased morbidity and mortality, Meymandi says targeted outreach toward high-risk Latin American immigrants in the US is necessary. Her hospital runs a program "where we go into the community and provide screening in conjunction with the churches, because it's a trusted environment," she explained.

In that population of normal "healthy" individuals, "we are finding a 1% prevalence of Chagas disease. So it's significant, and if we catch it early and treat it, we can either cure it or slow down the progression of the disease."

 
If we catch it early and treat it, we can either cure it or slow down the progression of the disease.
 

The only drugs available for treating the disease, the triazole derivatives nifurtimox and benznidazole, are not approved by the FDA and are therefore not available by prescription in the US. Meymandi has to go through the CDC, under a research protocol, and the WHO provides the drugs to the CDC for distribution in the US.

Treatment involves either a three-month course of nifurtimox, which is taken three times a day, or a two-month course of twice-daily benznidazole. Both medicines are almost 100% effective in curing the disease if given soon after infection at the onset of the acute phase. However, the efficacy of both diminishes the longer a person has been infected.

"We are hopeful to catch them earlier; that's why we have our outreach program. We treat them with the antiparasitics, and then we follow them annually. We do echos and cardiac MRI." She says compliance with the antiparasitic medicines "is good" despite side effects, something she ascribes to the fact that much of this work is coordinated through the church environment.

MRI "is really important in this patient population," she notes, "because it shows the scarring, which you can't tell from an echocardiogram. LV function [of Chagas sufferers] may be normal, but they'll have a lot of scarring. Then we will take them and perform an [electrophysiologic] EP study."

 
If you have a Hispanic last name and a bundle branch block, you will get a call, and we will have you come in for testing.
 

Other than this, says Meymandi, patients often present having had a cardiac arrest "so that's how we initially diagnose them." Also, "routinely we screen patients who have any type of bundle branch block [BBB] on their ECG. If you have a Hispanic last name and a BBB, you will get a call verifying that you are Latin American, and then we will have you come in for testing." Other classic echocardiographic presentations of Chagas include segmental wall-motion abnormalities and apical aneurysms, she noted.

Meymandi says LA currently has a large population of immigrants from El Salvador, Mexico, and Bolivia in whom they are finding Chagas, although it can affect anyone from Central or South America. She has also recently treated two people in the US who were not of Latin American descent, but observed, "You have to be outdoorsy, you have to expose yourself to the bug."

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