Original Article
Chagas' Heart Disease in the United States
N Engl J Med 1991; 325:763-768September 12, 1991
- Abstract
- Abstract
Background and Methods.
Chagas' heart disease is believed to be rare in the United States, although many persons from countries where the disease is endemic reside here. We performed a retrospective case review and prospective follow-up of 25 patients with Chagas' heart disease and no obstructive coronary artery disease on angiography.
Results.
The patients mainly presented with symptomatic atrioventricular block, congestive heart failure, anginal chest pain, sudden death averted by resuscitation, or sustained ventricular tachycardia. Of the 25 patients, 18 had been treated for coronary artery disease or idiopathic dilated cardiomyopathy for up to 108 months before the diagnosis of Chagas' disease was considered. The electrocardiograms frequently suggested coronary artery disease. Six of the seven patients who had exercise thallium-perfusion scans had abnormalities suggesting ischemia or infarction. A left ventricular aneurysm was found in 14 of the 25 patients, segmental akinesia or hypokinesia in 5, and diffuse hypokinesia in 3. Programmed ventricular Stimulation performed in 13 patients induced sustained ventricular tachycardia in 9 and nonsustained ventricular tachycardia in 2.
Actuarial survival (mean ±SE) after four years for the entire group was 56±12 percent; it was 32±16 percent among those with global left ventricular dysfunction, and 78±14 percent among those without such dysfunction (P = 0.03). Only patients with left ventricular dysfunction or an aneurysm died (four-year survival, 45±14 percent, as compared with 100 percent for the remaining patients; P = 0.0002). Heart failure and left ventricular aneurysm or dysfunction were the only independent predictors of death. Nine patients required permanent pacemakers.
Conclusions.
In the United States, Chagas' heart disease commonly mimics coronary artery disease or idiopathic dilated cardiomyopathy. The prognosis is poor for patients with heart failure or left ventricular aneurysm or dysfunction. The disease may be underdiagnosed in the United States. (N Engl J Med 1991; 325: 763–8.)
Media in This Article
Figure 1
Actuarial Survival of Patients with Chagas' Disease Who Underwent Angiography and Those Who Did Not, and Survival in the Entire Group.Figure 2
Survival of Patients in the Angiography Group Who Had Left Ventricular (LV) Dysfunction or Aneurysm and Those Who Did Not.Article Activity
- Article
CHAGAS' disease with cardiac involvement is an important public health problem in countries where Trypanosoma cruzi and its triatomid vector (the reduviid bug) are found in proximity to human habitation. It is likely that between 16 and 18 million people worldwide are infected with T. cruzi and that more than 90 million are at risk.1 2 3 Up to 30 to 40 percent of those infected will ultimately have some degree of cardiac involvement,4 , 5 which is the leading cause of cardiovascular death in areas where the disease is endemic.6 Chagas' heart disease is believed to be rare in the United States; there have been only eight cases reported, all among Latin American immigrants.7 8 9 10 11 12 13 There are estimated to be more than 100,000 infected persons now residing in the United States, however, and it has been suggested that cases will be encountered in increasing numbers.14 , 15 Because the diagnosis is often missed or overlooked in this country, we reviewed the cases of Chagas' heart disease diagnosed at our institution to determine the presentation, clinical findings, and outcome.
Methods
We reviewed the case histories of all patients at the Los Angeles County—University of Southern California Medical Center who had a positive serologic test for T. cruzi from 1974 through December 1990. Since pathological verification of T. cruzi infection of the heart is rare,16 we used a case definition of Chagas' heart disease that required a combination of epidemiologic, serologic, and clinical criteria to be met.17 These included (1) a history of residence in an area where Chagas' disease was endemic, (2) an unequivocally positive serologic test for T. cruzi, (3) a clinical syndrome compatible with Chagas' heart disease, and (4) no evidence of another cardiac disorder to which the findings could be attributed. Chagas' disease can resemble coronary disease; therefore, only the 25 patients who had no evidence of obstructive coronary artery disease on coronary arteriography were considered to have definite Chagas' heart disease for the purposes of this report; the remainder were considered to have probable Chagas' heart disease. Compatible clinical syndromes included atrioventricular conduction abnormalities, apical left ventricular aneurysms, and segmental wall-motion abnormalities not attributable to coronary artery disease; idiopathic dilated cardiomyopathy, with or without a segmental wall-motion abnormality; symptomatic ventricular arrhythmias; and any combination of these findings. Patients without demonstrable cardiac abnormalities were considered to have disease of indeterminate phase and were excluded from this review. Thyroid disease and iron overload were suspected in 66 percent and 14 percent of the patients, respectively, and were excluded by appropriate testing. Alcohol abuse or other causes of cardiomyopathy were not present in any patient.
We reviewed the patients' clinical histories at the time of the initial cardiac evaluation and collection of data by noninvasive and invasive methods (cineangiography, echocardiography, electrocardiography, exercise testing, and electrophysiologic studies). Global left ventricular systolic dysfunction was defined by the presence of an ejection fraction below 0.50, or if the ejection fraction had not been measured (as was true for three patients), a fractional shortening of the left ventricular cavity by less than 28 percent in the parasternal view on M-mode echocardiography. Left ventricular aneurysm was defined by the presence of an outward bulging of the ventricular contour during both diastole and systole.
The follow-up period began with the time of initial presentation. Follow-up status was ascertained from clinical records and follow-up visits and, as of January 1991, from telephone interviews or home visits with all patients by one of the investigators. Follow-up was complete for 23 of the 25 patients; 2 were lost to follow-up after 7 and 12 years. Cardiac death was considered sudden if it occurred unexpectedly without preceding symptoms.
Serologic testing was performed by two methods18 in all patients. Testing was performed by the Centers for Disease Control until December 1988, and by the State of California Microbial Disease Laboratory thereafter. Complement-fixation tests (the Machado—Guerreiro test) were carried out on all samples (with a positive test indicated by a reaction with a dilution of serum at or above 1:8). For the second test, immunohemagglutination (positive reaction, at or above a 1:64 dilution of serum) was used from 1976 through 1981, and indirect immunofluorescence (positive reaction, at or above a 1:32 dilution) was used from 1982 to the end of the study. The complement-fixation test has a sensitivity of 90 percent and a specificity over 98 percent in cases of late disease; the sensitivity of indirect immunofluorescence is higher.18
Survival was calculated by life-table analysis; mean (±SE) values are given. For other data, means (±SD) are provided. Continuous variables were compared by t-tests, and discrete variables by the chi-square test with Fisher's exact test when appropriate. Clinical variables that were significantly related to prognosis on the basis of univariate analysis were entered into a nonparametric multivariate analysis of survival (Lifetest procedure, SAS Institute); significance was assessed with the Wilcoxon test. All P values are two-tailed.
Results
Forty-two patients met the criteria for inclusion in the study. Thirty-eight had positive serologic tests by the two methods; in the remaining four patients who had positive tests by only one method, the clinical picture was strongly suggestive of Chagas' heart disease. One patient has been described elsewhere.9 Of the 42 patients, 14 were given diagnoses from 1975 through 1985, and 28 from 1986 through 1990. The patients' countries of birth were as follows: El Salvador, 17 patients; Mexico, 12; Guatemala, 4; Nicaragua, 3; Honduras and Argentina, 2 each; and Colombia and Bolivia, 1 each. All the patients had resided in earth-walled or thatch-roofed dwellings in rural areas where Chagas' disease was endemic. None could recall having symptoms compatible with those of acute Chagas' disease.
Patients Who Underwent Angiography
Twenty-five of the 42 patients underwent coronary arteriography; 23 had normal coronary arteries, and 2 had nonobstructive coronary disease. These 25 were considered to have definite Chagas' heart disease, and they are the focus of this report. Among them were 7 men and 18 women, with a mean (±SD) age of 53±14 years. At the initial evaluation, the patients had been symptomatic for 19±29 months. Their presenting manifestations are listed in Table 1.Table 1
Characteristics of the Patients at Clinical Presentation. Eighteen patients (72 percent) had received treatment for other presumed cardiac disorders (coronary artery disease or idiopathic dilated cardiomyopathy) for periods of up to 108 months (mean, 20±33) before Chagas' disease was considered a possible diagnosis.Electrocardiographic Abnormalities
The initial electrocardiogram was abnormal for all patients (Table 2Table 2
Initial Electrocardiographic Findings.). Conduction abnormalities, pathologic Q waves, and multiple abnormalities were common. Five of six patients who had ST-segment elevations had pathologic Q waves; thus, the electrocardiogram mimicked that typical of patients with recent anterolateral or inferolateral infarction. Four of these patients had left ventricular aneurysms.Left Ventricular Function and Coronary Arteriography
Thirteen patients had global left ventricular dysfunction. Seven of the 14 patients with left ventricular aneurysms had normal global left ventricular function. The left ventricular aneurysms usually involved the apex as well as the posterolateral wall and varied in size and morphology from fingertip-sized outpouchings to large structures. Twenty-two patients (88 percent) had abnormal left ventricular wall motion; 14 of them had a left ventricular aneurysm (Table 3Table 3
Left Ventricular Function and Coronary Arteriographic Findings in the Angiography Group.). A segmental wall-motion abnormality without aneurysm (usually apical akinesia) was found in five patients, and diffuse wall-motion abnormality in three. Seven patients had multiple segmental wall-motion abnormalities. Coronary arteriography was normal in 23 patients; 2 patients had mild stenosis of a small branch vessel that was not associated with wall-motion abnormality in its distribution.Exercise Testing
Treadmill testing was performed in 11 patients; chest pain occurred in 2, ST-segment depression in 1, and ST-segment elevation in 1 who had a left ventricular aneurysm. All seven patients who had exercise thallium 201 imaging had abnormal studies. Fixed defects were found in two patients, a reversible defect in one, and both fixed and reversible defects in three. In six patients, the defect identified on thallium scanning corresponded to an area of abnormal left ventricular wall motion or aneurysm; the seventh scan showed reverse redistribution — that is, a greater washout of thallium on the delayed images.
Ambulatory Electrocardiographic Monitoring
All 19 patients who underwent ambulatory electrocardiographic monitoring had frequent unifocal or multifocal premature ventricular beats. Runs of ventricular tachycardia were noted in seven patients, five of whom had inducible ventricular tachycardia on subsequent programmed ventricular stimulation; six other patients with inducible ventricular tachycardia and four with subsequent spontaneous ventricular tachycardia or sudden death had no ventricular tachycardia on a single 24-hour electrocardiographic recording.
Electrophysiologic Findings
Thirteen patients underwent programmed ventricular stimulation to evaluate sudden death averted by resuscitation (two patients), sustained ventricular tachycardia (two), nonsustained ventricular tachycardia (six), or syncope (three); nine had inducible sustained ventricular tachycardia or ventricular fibrillation, and two had nonsustained ventricular tachycardia.
Follow-up
The patients were followed for 53±63 months (range, 1 to 202). There were eight deaths, all due to cardiac causes, which occurred a mean of 22±9 months after presentation. The age at death was 49±12 years (range, 29 to 65). Death was sudden for six patients, of whom four had aneurysms and two had diffuse left ventricular dysfunction with congestive heart failure. The two remaining deaths were due to congestive heart failure. Sudden cardiac death and sustained ventricular tachycardia occurred together more frequently in patients with left ventricular aneurysm or dysfunction (Table 4Table 4
Incidence of Clinical Events In the Patients Studied, According to the Presence or Absence of Left Ventricular Aneurysm or Dysfunction.*). All the deaths of patients with left ventricular aneurysms were sudden. Most of the deaths occurred soon after initial evaluation; actuarial survival after four years was 56±12 percent (Fig. 1Figure 1Actuarial Survival of Patients with Chagas' Disease Who Underwent Angiography and Those Who Did Not, and Survival in the Entire Group.). Survival was poor in the patients with global left ventricular dysfunction (32± 16 percent after four years, as compared with 78±14 percent in those with normal global left ventricular function; P = 0.02) and in those with any left ventricular dysfunction or aneurysm (45±14 percent after four years, as compared with 100 percent in those with neither abnormality; P = 0.0002) (Fig. 2Figure 2Survival of Patients in the Angiography Group Who Had Left Ventricular (LV) Dysfunction or Aneurysm and Those Who Did Not.).The historical features associated most strongly
with a fatal outcome were congestive heart failure at initial presentation (mortality, 100 percent in patients presenting with heart failure [n = 5], as compared with 15 percent in those without it; P<0.001) or its occurrence during follow-up (mortality, 56 percent in those with heart failure, as compared with 19 percent in those without it; P = 0.02). Presentation with sustained ventricular tachycardia or sudden death averted by resuscitation was not associated with a higher risk of subsequent death. The patients who died had larger left ventricular volumes than those who survived (end-diastolic volume index, 200±65 vs. 102±31 ml per square meter; P = 0.006) and more frequent ST-segment elevation (50 percent vs. 12 percent, P = 0.006) and pathologic Q waves (88 percent vs. 41 percent, P = 0.04). Stepwise multiple regression of the life-table data demonstrated that congestive heart failure (P = 0.0002) and the presence of either left ventricular aneurysm or left ventricular dysfunction (P = 0.003) were the only independent predictors of subsequent death.
Nine patients in whom sustained ventricular tachycardia or ventricular fibrillation could be induced were treated with invasively guided antiarrhythmic therapy, an implantable cardioverter defibrillator, or left ventricular aneurysmectomy. There was only one death in this group, a sudden death in a patient with severe left ventricular dysfunction without an aneurysm who had refractory ventricular arrhythmias. Two patients had inducible monomorphic ventricular tachycardia that terminated spontaneously; one of them died suddenly. Two patients had no inducible arrhythmia and were treated with empirical or noninvasively guided antiarrhythmic therapy; both died suddenly.
Nine patients received pacemakers for symptomatic second- or third-degree atrioventricular block. Left ventricular aneurysm and dysfunction were no more frequent in these patients than in those who did not receive pacemakers; nor were congestive heart failure, arrhythmic events, and death more frequent in the patients with pacemakers. Proarrhythmic effects of antiarrhythmic agents were documented in three patients.
Patients Who Did Not Undergo Angiography
The 17 patients who did not undergo coronary arteriography were classified as probably having Chagas' disease, and the findings for them are shown in Tables 1 and 2. The mean age in this group of patients was 51±13 years. The patients were less likely to have presented with serious arrhythmias; pathologic Q waves and ventricular ectopic beats were also less common. This group was less likely than the other patients to have left ventricular aneurysm or dysfunction (47 percent vs. 80 percent, P = 0.02), and there was a nonsignificant trend in this group toward better survival (75 percent vs. 56 percent at four years, P = 0.29). Fifteen were women. None had risk factors for coronary artery disease. Sixteen had no symptoms suggestive of coronary heart disease; one with chest pain had a normal thallium stress scan. Only one patient in this group had a left ventricular aneurysm; it was very small and located at the apex. In the group without angiography and the total group, four-year survival was 75±13 percent and 63±9 percent, respectively. The predictors of death in the total group were the same as in the angiography group.
Discussion
This study of patients with Chagas' heart disease in the United States describes the presentation of the disease, its varied manifestations, and its natural history outside the areas in which the disease is endemic. Though rarer than other forms of heart disease, Chagas' heart disease occurs in the southwestern United States among persons who emigrate from areas of endemic disease. The greater number of patients receiving diagnoses after 1986 than in earlier years reflects both increased awareness of the disease and an increase in the number of patients from areas where the disease is endemic. Chagas' disease commonly presents with atrioventricular block, congestive heart failure, anginal chest pain, conduction abnormality on electrocardiogram, sudden death averted by resuscitation, or ventricular tachycardia. The clinical picture mimics that of coronary artery disease as well as idiopathic dilated cardiomyopathy. The prognosis is poor for patients with heart failure and left ventricular aneurysm or global systolic dysfunction.
Chagas' disease is widespread in Central and South America. It is the most common cause of dilated cardiomyopathy in countries where the disease is endemic19 and is responsible for over 30 percent of deaths from any cause and nearly all deaths from cardiovascular causes in areas where the disease is endemic.20 The spectrum of Chagas' heart disease in these areas is much broader than in our series, possibly because we may have failed to recognize many subtle cases. In affected areas, large numbers of patients have mild forms of disease, such as isolated conduction abnormalities; the outcome in these patients may be more benign.6 , 19 , 20 Those infected may remain free of end-organ disease for life.21 Acute Chagas' disease characterized by a febrile illness, sometimes associated with facial or unilateral palpebral edema (Romaña's sign), is uncommon. Acute myocarditis develops in a small minority and is fatal in about 10 percent.3 Late manifestations of the disease, usually cardiac disease but also megacolon or achalasia caused by autonomic denervation of these organs,22 develop after a latency period of 15 to 20 years or more4 in up to 30 to 40 percent of those infected.3 Because there is no effective antiparasitic treatment for the chronic stage of Chagas' disease,23 preventive measures to protect the public health are of particular importance.24
The late cardiac involvement in Chagas' disease presents a unique pathological picture, characterized by chronic myocarditis, focal and diffuse loss of myocytes, fibrosis, and focal atrophy, in which areas of thin-walled fibrous tissue are left behind.25 , 26 The process is most commonly evident in the conduction system and the left ventricular apex. Involvement of the conduction system always accompanies cardiac involvement,27 producing right bundle-branch block, left anterior fascicular block, or both in up to 80 percent of patients,28 with possible progression to complete atrioventricular block. Myocardial involvement leads to the formation of the typical narrow-necked left ventricular aneurysm at the apex or, less commonly, adjacent to the mitral annulus. Localized areas of akinesia or dyskinesia commonly occur.29 When myocardial involvement is diffuse, a picture typical of dilated cardiomyopathy develops. The pathogenesis of this process is poorly understood, but it is chronic and progressive. Autoimmunity,30 microvascular dysfunction,31 and autonomic denervation have been implicated.32 , 33
Life-threatening ventricular arrhythmias and sudden death are frequent in patients with a left ventricular aneurysm or global dysfunction,34 and they may be the first manifestation of the disease.35 In our series, 24 percent of patients in the angiography group presented with sudden death averted by resuscitation or sustained ventricular tachycardia, and sustained ventricular tachycardia or sudden death occurred subsequently in 40 percent of the patients with left ventricular aneurysm or dysfunction. Programmed ventricular stimulation in selected patients revealed a high incidence of inducible sustained ventricular tachycardia. Sudden death, presumably from an arrhythmia, was the most frequent cause of death even when programmed ventricular stimulation did not induce sustained arrhythmias.
In this study, chronic congestive heart failure, left ventricular dysfunction, and left ventricular aneurysm were strong predictors of death and arrhythmic events. The relation of left ventricular abnormalities to clinical events and prognosis in our patients is an important finding and has not been assessed in most longitudinal studies of Chagas' heart disease. Congestive heart failure was the strongest predictor of death in this series as well as in others.36 The degree of left ventricular dysfunction and the mortality rate were similar among the patients who required a pacemaker and among those who did not.
Our study provides useful clinical information on the presentation, clinical features, and outcome of the disease; furthermore, our sample comprised a case mix comparable to that likely to be seen among patients from areas of endemic disease who reside in the United States.
Presented in part at the Annual Scientific Session of the American College of Cardiology, New Orleans, March 18 to 22, 1990.
We are indebted to the large number of physicians who over a period of 16 years performed clinically indicated laboratory testing in our patients.
Source Information
From the Division of Cardiology, Department of Medicine, Los Angeles County—University of Southern California Medical Center and University of Southern California School of Medicine, Los Angeles. Address reprint requests to Dr. Rahimtoola at the Division of Cardiology, University of Southern California, 2025 Zonal Ave., Los Angeles, CA 90033.
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