Young Native Americans had increased left ventricular thickness and left ventricular hypertrophy after being exposed to arsenic, and had a greater risk if they showed signs of prehypertension or hypertension, according to recent research.
Dr. Gernot Pichler
“The stronger association in subjects with elevated blood pressure suggests that individuals with preclinical heart disease might be more prone to the toxic effects of arsenic on the heart,” Gernot Pichler, MD, PhD, a cardiologist at Hospital Hietzing/Heart Center Clinic Floridsdorf in Vienna, stated in a press release.
Dr. Pichler and colleagues evaluated 1,337 individuals (mean age, 31 years; 61% female) in the Strong Heart Family Study, an extension of the Strong Heart Study that was designed to study cardiovascular disease in Native Americans. The researchers noted that, while the studies were not originally intended to evaluate arsenic exposure in these populations, “the importance of studying arsenic was recognized overtime as increasing evidence supported the role of arsenic in cardiovascular disease and the relatively high arsenic exposure in tribal communities, compared to other general populations in the United States.”
Arsenic exposure was determined through the sum of inorganic and methylated arsenic concentrations in urine, and researchers used transthoracic ECG at baseline and follow-up to compare left ventricular geometry and function. The mean follow-up was 5.6 years and baseline median sum of inorganic and methylated arsenic concentrations in urine was 4.24 (interquartile range, 2.82-6.90) mcg/g creatinine.
Prevalence of left ventricular hypertrophy was 4.6% overall, and the odds ratio of left ventricular hypertrophy per 100% increase in arsenic in the urine was 1.47 (95% confidence interval, 1.05-2.08) overall and 1.58 for individuals with prehypertension or hypertension (95% CI, 1.04-2.41).
“People drinking water from private wells, which are not regulated, need to be aware that arsenic may increase the risk for cardiovascular disease,” said Dr. Pichler. “Testing those wells is a critical first step to take action and prevent exposure.”
Prospective and cross-sectional analyses both showed changes in left ventricular geometry – such as in the left atrial systolic diameter, interventricular septum, and left ventricular posterior wall thickness and mass index – were associated with exposure to arsenic. In addition, left ventricular function factors such as isovolumic relaxation time and stroke volume were also affected by arsenic exposure. However, the researchers noted that their study was limited by a single method of arsenic exposure and having no long-term follow-up for participants.
“The study raises the question of whether the changes in heart structure are reversible if exposure is reduced. Some changes have occurred in water sources in the study communities, and it will be important to check the potential health impact of reducing arsenic exposure,” said Dr. Pichler.
This study was funded by the National Institute of Health Sciences and grants from the National Heart, Lung, and Blood Institute. The authors reported no relevant conflicts of interest.
SOURCE: Pichler G et al. Circ Cardiovasc Imaging. 2019 May 1. doi: 10.1161/CIRCIMAGING.119.009018.