Chagas Cardiomyopathy—Where Do We Stand After a Hundred Years?
Section snippets
Epidemiology and natural history
Chagas disease has a wide distribution in Central and Latin America; epidemiologic studies carried out in 1980 to 1985 estimated a prevalence of 16 to 18 million persons infected and 100 million at risk.3 Fortunately, successful vector-control strategies reduced the transmission of Chagas disease in several Latin American countries; and therefore, its incidence was reduced by more than 65% in 2000. Initially a disease of rural areas in endemic countries, the disease has spread to cities with
Pathogenesis
The pathogenesis of Chagas cardiomyopathy is not completely understood, partially because disease progression depends on complex host-parasite interactions. Four main pathogenetic mechanisms have been described: direct parasite damage to the myocardium, immunologic mechanisms, dysautonomia, and microvascular disturbances.11, 12
Etiologic diagnosis
The diagnosis of T cruzi infection is usually established by the detection of the parasite using parasitologic tests, during acute infection, or by immunodiagnosis, through detection of circulating antibodies against T cruzi antigens, in the chronic phase of disease. In the acute phase of disease, laboratory confirmation is based on the detection of parasites using the fresh-blood test, the more sensitive and preferred one, or by smear and thick drop tests. Concentration tests should be
Clinical manifestations and clinical assessment
Chagas cardiomyopathy is the most important clinical presentation of Chagas disease and comprises a wide range of manifestations, including heart failure, arrhythmias, heart blocks, sudden death, thromboembolism, and stroke.48 Clinical presentation typically varies widely according to the degree of myocardial damage; and most patients present a mild form of heart disease, frequently characterized only by the presence of asymptomatic abnormalities on the ECG or in other complimentary
Diagnostic evaluation
The ECG is the single most important examination in Chagas cardiomyopathy. Numerous epidemiologic studies have shown that patients with a normal ECG have an excellent medium-term survival. 49, 50, 51 Moreover, severe global left ventricular dysfunction, the main prognostic marker in Chagas disease, is rare in such patients. The greater the number and severity of ECG alterations registered in a same tracing, the more advanced the myocardial damage possibly is, and the worse the prognosis should
Staging and prognosis
Several classification systems were developed in Chagas cardiomyopathy to take into account the great clinical pleomorphism of this disease and to aid in its clinical management. The Kuschnir et al112 and Los Andes64 classification systems are frequently used in longitudinal studies.87, 90, 113, 114 More recently, a Brazilian committee of experts proposed another staging system,45 based mainly on international heart failure guidelines (Table 2).115, 116 The main virtue of this new
Treatment of Chagas cardiomyopathy
The main focus of the management of Chagas cardiomyopathy relies on the treatment of the 3 main syndromes: heart failure, arrhythmias, and thromboembolism. There are, however, clinical features characteristically Chagas related that deserve special attention in regard to therapeutic approaches. At the present time, there is limited evidence-based clinical data to support specific antiparasitic therapy; but few data and an increasingly comprehensive understanding of physiopathologic aspects
Treatment of cardiomyopathy (heart failure, arrhythmias, thromboembolism)
Traditional therapeutic strategies for heart failure such as angiotensin-converting enzyme (ACE) inhibitors and β-blockers are likely as important in Chagas cardiomyopathy as in other heart failure syndromes. However, there are very poor evidence-based strategies focusing on Chagas disease specifically. Small studies have pointed similar beneficial effects of ACE inhibitors in Chagas cardiomyopathy. In fact, both captopril and enalapril have been shown to improve functional class and left
Antiarrhythmic strategies
Treatment of ventricular arrhythmia in Chagas cardiomyopathy is essentially empirical and not supported by large randomized controlled trials. This is to say that there are no properly designed prospective trials in larger groups of patients with Chagas disease to ascertain whether pharmacologic or device therapy for ventricular arrhythmias prevents sudden cardiac death. Thus, clinical management may be subject to large variations in different settings; and recommendations are mainly empirical.
Heart transplantation
Chagas disease may account for important portions of the population referred for heart transplantation in areas where the disease is endemic. In certain parts of the world, it is the leading referring cause and in Brazil is the third indication for heart transplantation.149, 150 A number of uncertainties surround the context of transplanting patients with Chagas cardiomyopathy, the important ones being when to refer for transplantation, fear of reactivation of the parasitic infestation, higher
Preventing disease
Prevention in Chagas disease is 3-fold. Primary prevention aims to limit spread at the vectorial level, and blood transfusion and organ donation from infected donors. Secondary prevention aims to limit early and asymptomatic disease from progressing into fully developed syndrome. Tertiary prevention aims to limit, whenever possible, further organ damage and improve clinical outcome once the complete cardiomyopathy is established.160
Upcoming challenges
Globalization has made Chagas disease a less geographically restricted health condition. In fact, growing migration involving rural to urban areas in Latin American countries and also to large metropolitan areas outside Latin America is slowly transforming the reality worldwide. It is worth noting that there has been an impressive increase in positive test results for T cruzi in screened blood bank across the United States in the last decade, which enhanced the level of awareness of health
Future perspectives
Although the number of new cases of Chagas disease has dropped markedly in the last few years because of effective control programs, there is a large population of individuals who will clearly benefit from adequate clinical management. For instance, it would be desirable to have a comprehensive knowledge about some neglected clinical manifestations such as embolic stroke and chest pain. The identification of early markers of worse prognosis would be also an important advance, helping identify a
Statement of Conflict of Interest
All authors declare that there are no conflicts of interest.
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Statement of Conflict of Interest: see page 311.