Relationship was stronger in participants with pre-hypertension or hypertension
Elevated arsenic exposure was linked with left ventricular (LV) hypertrophy and LV wall thickness, an analysis of the longitudinal, population-based Strong Heart Family cohort found.
Taking into account two times more arsenic found in urine, the investigators found a 47% greater risk of thickening of the heart's primary pumping chamber across the entire cohort, reported Gernot Pichler, MD, PhD, of the Institute for Biomedical Research Hospital Clinic de Valencia in Spain, and colleagues.
There was also a 58% increased chance of thickening of the left ventricle in pre-hypertension and hypertension patients, the investigators reported in Circulation: Cardiovascular Imaging.
The continuous measures of LV geometry consisting of left atrial systolic diameter, interventricular septum, LV mass index, and LV posterior wall thickness were significantly and positively associated with arsenic exposure in both prospective and cross-sectional analyses. Among measures of LV function, isovolumic relaxation time and stroke volume were significantly related to arsenic exposure, they added.
LV hypertrophy (LVH), LV diastolic, and LV systolic dysfunction are considered effective surrogate markers for clinical cardiovascular disease (CVD), and outcomes contribute useful prognostic data on these events, noted Rajiv Chowdhury, MBBS, PhD, and Kim van Daalen, MPhil, both of the University of Cambridge in England, in an accompanying editorial.
"Moreover, identification of abnormal transthoracic echocardiography (TTE) measurements, such as LVH, in asymptomatic patients can favorably affect adverse trends through efficient primary and secondary preventative interventions. Despite this, experimental and epidemiological evidence of cardiac anatomical and functional alterations in populations with arsenic exposure is limited and non-existent in adult human populations," they continued.
The present investigation sheds light on the observational links between LV function and geometry and inorganic arsenic, but further investigation is required, the editorialists noted. "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," they wrote.
The researchers evaluated 1,337 American Indians from the Strong Heart Family Studyover a mean follow-up of 5.6 years. The cohort was 61% female and had a mean age of 30.7 years. All participants were ages ≤50 and had a relatively low burden of cardiovascular risk factors. Participants were from Oklahoma, South and North Dakota, and Arizona and had been exposed to drinking water with moderate-to-low amounts of arsenic.
Exclusion criteria were lacking urine arsenic data at phase IV, incomplete baseline information on TTE-measured variables at phase IV, inadequate information on co-variables of interest, and outlier levels of TTE variables as indicated by values of ≥2*percentile 99th.
The investigators used the sum of methylated and inorganic arsenic concentrations in urine (ΣAs) found at baseline as a biomarker of arsenic exposure. LV functioning and geometry were evaluated using transthoracic end-cardiographs at baseline and during the follow-up period.
The authors reported that the median of ΣAs was 6.9 μg/g creatinine, and that increased arsenic exposure was associated with prevalent LVH, with an odds ratio per a two-fold increase in ΣAs of 1.47 (95% CI 1.05, 2.08) in all participants, and an OR 1.58 (9% CI 1.04, 2.41) among pre-hypertensive or hypertensive individuals, but not with incident LVH.
The editorialists pointed out several "minor" limitations of the study -- urine arsenic is often from recent exposure the day before, and individuals may encounter arsenic from a number of external sources, including food, as well as from co-occurring environmental metals on a daily basis.
"One major limitation of the present study is that measures of urinary arsenic were available at baseline but not at follow-up," the investigators acknowledged. "Further research is needed to elucidate the causal pathways underlying this relationship and whether these associations are reversible after arsenic exposure is removed from drinking water."
The study was supported by the National Institute of Health Sciences and National Heart, Lung, and Blood Institute.
Pichler and co-authors disclosed no relevant relationships with industry.
Circulation: Cardiovascular Imaging
Source Reference: Pichler G, et al "The association of arsenic exposure with cardiac geometry and left ventricular function in young adults: evidence from the strong heart family study" Circ Cardiovasc Imaging 2019; DOI: 10.1161/CIRCIMAGING.119.009018.
Circulation: Cardiovascular Imaging
Source Reference: Chowdhury R and van Daalen K "Arsenic: a metal that might break your heart" Circ Cardiovasc Imaging 2019; DOI: 10.1161/CIRCIMAGING.119.009185.
Read the original article on Medpage Today: LV Hypertrophy Tied to Arsenic-Laced Water