Criteria
Introduction
There have been many attempts to define a classification system that allows patients to be placed into well-defined subgroups in relation to prognosis; however, there has been no clear consensus on these systems, and it is important to recognize the diversity across diagnostic criteria in order to avoid a misleading diagnosis.
The nomenclature used across different classification systems is identical and uses the letters A, B, C, and D; however, the classification may refer specifically to chronic cardiac forms of the disease (as with the Brazilian consensus classification), or all patients with chronic disease, including the indeterminate form (as with the American College of Cardiology/American Heart Association, modified Los Andes, and modified Kuschnir classifications). Groups in each classification may correlate with groups in other classifications.
Chronic Chagas disease: American College of Cardiology/American Heart Association classification[2]
A: patients at risk for developing heart failure; positive serology for Trypanosoma cruzi; neither structural cardiomyopathy or heart failure symptoms; normal ECG; no digestive changes (indeterminate form)
B1: patients with structural cardiomyopathy evidenced by electrocardiographic or echocardiographic changes, but with normal ventricular function and neither current or previous signs and symptoms of heart failure
B2: patients with structural cardiomyopathy characterized by global ventricular dysfunction and neither current or previous signs and symptoms of heart failure
C: patients with ventricular dysfunction and current or previous symptoms of heart failure (New York Heart Association functional class I, II, III, or IV)
D: patients with refractory symptoms of heart failure at rest despite optimised clinical treatment requiring specialized interventions.
Note: arrhythmias and conduction disease can occur from category B1 through to category D. Categories B1 through D are classified as Chagas cardiomyopathy, while categories B2 through D are also classified as Chagas dilated cardiomyopathy/heart failure.
Chagas cardiomyopathy: Brazilian consensus classification[13][161]
Only used for patients with Chagas cardiomyopathy. Patients with the chronic indeterminate form are not present in this classification because they have an excellent prognosis, similar to people without Chagas disease.
A: abnormal ECG findings, normal echocardiogram findings, no signs of congestive heart failure (CHF)
B1: abnormal ECG findings, abnormal echocardiogram findings with left ventricular ejection fraction (LVEF) >45%, no signs of CHF
B2: abnormal ECG findings, abnormal echocardiogram findings with LVEF <45%, no signs of CHF
C: abnormal ECG findings, abnormal echocardiogram findings, compensated CHF
D: abnormal ECG findings, abnormal echocardiogram findings, refractory CHF.
Chagas cardiomyopathy: modified Los Andes classification[162]
In this system, group IA represents patients with the chronic indeterminate form of the disease. This classification differs to the others in that it contains a subgroup of patients with normal ECG, but with minimal changes in the echocardiogram. There is considerable overlapping of prognosis between some groups.
IA: normal ECG findings, normal echocardiogram findings, no signs of CHF
IB: normal ECG findings, abnormal echocardiogram findings, no signs of CHF
II: abnormal ECG findings, abnormal echocardiogram findings, no signs of CHF
III: abnormal ECG findings, abnormal echocardiogram findings, CHF.
Chronic Chagas disease: modified Kuschnir classification[163]
Similar to the American College of Cardiology/American Heart Association classification. An important limitation is the evaluation of heart size based on chest radiography, rather than echocardiogram.
0: normal ECG findings and normal heart size (usually based on chest radiography)
I: abnormal ECG findings and normal heart size (usually based on chest radiography)
II: left ventricular enlargement
III: congestive heart failure.
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