From the Journals

Arsenic exposure increases risk of left ventricular hypertrophy

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Uncertainties remain in link between arsenic and CVD

The results from Pichler et al. show the effects of recent arsenic exposure on left ventricular (LV) hypertrophy, but other questions remain as to the long-term effects of arsenic and its interactions with other environmental metals, Rajiv Chowdhury, MBBS, PhD, and Kim van Daalen, BSc, MPhil, wrote in a related editorial.

It has been established that chronic, low to moderate inorganic arsenic exposure may be linked to cardiovascular disease (CVD) and risk factors such as hypertension and diabetes, but it is unclear how different exposure pathways contribute as well as what pathophysiological mechanisms contribute to CVD, and whether arsenic directly or indirectly contributes to cardiac functioning or a worse cardiometabolic profile, respectively, they wrote.

While the results contribute to the understanding of arsenic exposure through drinking water and its relationship to LV function and geometry, urinary arsenic reflects recent exposure and cannot measure arsenic exposure over a period of time. The study also does not account for an individual’s CVD risk or LV functioning/geometry with daily exposure to co-occurring environmental metals, particularly heavy metals, together with arsenic. Factors such as genetics, age, gender, and nutrition also impact an individual’s reaction to arsenic, and studies should be able to differentiate inorganic arsenic obtained from food and other sources.

While “this elegant analysis ... helps to clarify the observational associations of [arsenic] with LV geometry and function, it stimulates further complimentary work,” they wrote. “Such studies would be essential since CVD remains the single leading cause of adult premature death worldwide, and millions of individuals globally are exposed to arsenic and other metal contaminants.”

Dr. Chowdhury and Dr. Daalen are from the cardiovascular epidemiology unit in the department of public health and primary care at the University of Cambridge (England).


 

FROM CIRCULATION: CARDIOVASCULAR IMAGING

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 of Hospital Hietzing/Heart Center Clinic Floridsdorf in Vienna, Austria

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.

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