Key result
Low T. cruzi parasitaemia was associated with a higher risk of mortality, cardiac transplantation, or LVAD implantation compared to undetectable parasitaemia (HR 3.66; 95% CI 1.11-12.21).
Why the study?
The study was conducted to analyse the effect of serum Trypanosoma cruzi parasite load assessed by RT-qPCR on the prognosis of patients with chronic Chagas cardiomyopathy.
Does circulating Trypanosoma cruzi load predict major cardiovascular outcomes in patients with chronic Chagas cardiomyopathy?
Cohort (n=100)
Does circulating Trypanosoma cruzi load predict major cardiovascular outcomes in patients with chronic Chagas cardiomyopathy?
Hazard Ratio: 3.66 (95% CI 1.11–12.21)
In patients with chronic Chagas cardiomyopathy, low parasitaemia is paradoxically associated with a higher risk of major cardiovascular outcomes and severity markers of myocardial injury compared to undetectable parasitaemia.
May identify higher-risk Chagas cardiomyopathy patients; hypothesis-generating and should not yet change practice.
OBJECTIVES: To analyse the effect of parasite load assessed by quantitative reverse transcription PCR (RT-qPCR) in serum on the prognosis of patients with chronic Chagas cardiomyopathy (CCM) after a 2-year follow-up. METHODS: Prospective cohort study conducted between 2015 and 2017. One hundred patients with CCM were included. Basal parasitaemia levels of Trypanosoma cruzi (T. cruzi) were measured using a quantitative polymerase chain reaction (qPCR) test. The primary composite outcome (CO) was all-cause mortality, cardiac transplantation and implantation of a left ventricular assist device. Secondary outcomes were the baseline levels of serum biomarkers and echocardiographic variables. RESULTS: After a 2 years of follow-up, the primary CO rate was 16%. A positive qPCR was not associated with a higher risk of the CO. However, when parasitaemia was evaluated by comparing tertiles (tertile 1: undetectable parasitaemia, tertile 2: low parasitaemia and tertile 3: high parasitaemia), a higher risk of the CO (HR 3.66; 95% CI 1.11-12.21) was evidenced in tertile 2. Moreover, patients in tertile 2 had significantly higher levels of high-sensitivity troponin T and cystatin C and more frequently exhibited an ejection fraction <50%. CONCLUSION: Low parasitaemia was associated with severity markers of myocardial injury and a higher risk of the composite outcome when compared with undetectable parasitaemia. This finding could be hypothetically explained by a more vigorous immune response in patients with low parasitaemia that could decrease T. cruzi load more efficiently, but be associated with increased myocardial damage. Additional studies with a larger number of patients and cytokine measurement are required to support this hypothesis.
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Echeverría et al. (2020) conducted a cohort in Chronic Chagas cardiomyopathy (n=100). Low parasitaemia (tertile 2) vs. Undetectable parasitaemia (tertile 1) was evaluated on All-cause mortality, cardiac transplantation and implantation of a left ventricular assist device (HR 3.66, 95% CI 1.11-12.21). Low T. cruzi parasitaemia was associated with a higher risk of mortality, cardiac transplantation, or LVAD implantation compared to undetectable parasitaemia (HR 3.66; 95% CI 1.11-12.21).
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