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Ten-Year Incidence of Chagas Cardiomyopathy Among Asymptomatic, T. Cruzi Seropositive Former Blood Donors
Study Questions:
What is the natural history of clinical Chagas disease in T. cruzi seropositive blood donors?
Methods:
The investigators performed a retrospective cohort study among initially healthy blood donors with an index T. cruzi seropositive donation and age, gender-matched, and period-matched seronegatives in 1996-2002 in the cities of Sao Paulo and Montes Claros, Brazil. In 2008-2010, all subjects underwent medical history, physical examination, electrocardiograms (ECGs), and echocardiograms. ECG and echo results were classified by blinded core laboratories, and records with abnormal results were reviewed by a blinded panel of three cardiologists who adjudicated the outcome of Chagas cardiomyopathy. Associations with Chagas cardiomyopathy were tested with multivariate logistic regression.
Results:
Mean follow-up time between index donation and outcome assessment was 10.5 years for the seropositives and 11.1 years for the seronegatives. Among 499 T. cruzi seropositives, 120 (24%) had definite Chagas cardiomyopathy, and among 488 T. cruzi seronegatives, 24 (5%) had cardiomyopathy, for an incidence difference of 1.85 per 100 person-years attributable to T. cruzi infection. Of the 120 seropositives classified as having Chagas cardiomyopathy, only 31 (26%) presented with ejection fraction below 50, and only 11 (9%) were classified as New York Heart Association class II or higher. Chagas cardiomyopathy was associated (p < 0.01) with male sex, a past history of abnormal ECG, and the presence of an S3 heart sound.
Conclusions:
The authors concluded that there is a substantial annual incidence of Chagas cardiomyopathy among initially asymptomatic T. cruzi seropositive blood donors, although the disease was mild at diagnosis.
Perspective:
This 10-year retrospective cohort study provides strong evidence for a moderate rate of progression to cardiomyopathy (1.85% per year) among persons infected with T. cruzi, but without cardiomyopathy at baseline. Prognostic factors for cardiomyopathy, including male sex, a past history of ECG abnormalities, and S3 gallop, may be useful in deciding which seropositives are at highest risk of cardiomyopathy and potentially eligible for treatment. The false-positive diagnoses of Chagas-like cardiomyopathy among 5% of T. cruzi seronegatives illustrate the difficulty of distinguishing Chagas from other cardiac disease, leading to overestimation of Chagas disease incidence in uncontrolled seropositive cohorts, but the inclusion of a T. cruzi seronegative comparison cohort in this study allowed measurement and elimination of competing morbidity due to other cardiovascular disease.
Keywords: Chagas Disease, Follow-Up Studies, Electrocardiography, New York, Heart Diseases, Incidence, Brazil, Biomarkers, Heart Failure, Cardiovascular Diseases, Chagas Cardiomyopathy, Physical Examination, Echocardiography
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