NEW YORK (Reuters Health) – Chronic Chagas disease in the elderly doubles their risk of dying from a stroke, and the risk is increased further in those with high B-type natriuretic peptide (BNP) levels and atrial fibrillation, Brazilian researchers report in the November issue of Stroke.

Dr. Maria Fernanda Lima-Costa told Reuters Health by email, “Parasitic infections are generally seen as a health problem for young individuals, and that their effects in the elderly are negligible. Our study showed that Chagas disease is a risk factor for stroke in the elderly, independently of conventional cardiovascular risk factors.”

She and her colleagues observe that about 30% of those chronically infected develop chagasic cardiomyopathy with heart failure, heart block, ventricular arrhythmias, and cardioembolic phenomena. In the last decade, evidence for increased risk of stroke has also emerged.

To investigate further, Dr. Lima-Costa of Fundacao Oswaldo Cruz, Belo Horizonte and her team studied 1398 residents of Bambui City, also in southeast Brazil, an area endemic for Chagas disease. All the subjects were aged 60 years or more.

In earlier work the researchers established that Trypanosoma cruzi infection disease was a strong predictor of 10-year mortality in this cohort. In the current study, they examined stroke risk in particular.

The baseline prevalence of T. cruzi infection was 37.5% and the overall mortality rate from stroke was 4.62 per 1000 person-years. However, the risk was twice as high in those infected (adjusted hazard ratio, 2.35).

BNP levels in the top quartile in this group were a strong predictor of mortality (adjusted hazard ratio, 2.85). In infected participants with both high BNP and electrocardiographic atrial fibrillation, the hazard ratio increased to 11.49.

The findings, the researchers point out, “add to previous studies by showing that first, high BNP levels predicted death from stroke in T. cruzi chronically infected elderly; and second, the presence of both BNP and atrial fibrillation increased substantially the risk of stroke mortality.”

“The results,” Dr. Lima-costa concluded, “provide evidence supporting the need for measures to reduce the burden of this parasitic disease in this growing segment of the population.”

Reference:
Chagas Disease Predicts 10-Year Stroke Mortality in Community-Dwelling Elderly. The Bambu