Anemia linked to heart muscle thickening in adults in Tanzania and Haiti

A new cross-sectional analysis of more than 4,000 adults in Tanzania and Haiti reports that moderate to severe anemia is strongly associated with thicker heart muscle and other echocardiographic signs of a high-output cardiac state, even in people whose blood pressure is normal or low. The findings, published in BMC Global and Public Health, position anemia as a potentially modifiable cardiovascular risk factor in settings where it is highly prevalent and often goes undiagnosed.

The research drew on two separate cohorts. In Mwanza, Tanzania, 999 adults aged 30 or older underwent echocardiography as part of the Mwanza HIV&CVD Cohort, which included 500 people with HIV and 499 people without HIV recruited from publicly funded HIV clinics between 2022 and 2023. In Port-au-Prince, Haiti, the Haiti Cardiovascular Disease Cohort enrolled 3,005 adults using multistage random sampling between 2019 and 2021; because echocardiography in Haiti was performed only in participants with hypertension or cardiovascular symptoms, the association analysis was restricted to the 1,162 participants who received the scan, with inverse probability weighting applied to account for the non-random selection.

The primary outcome was left ventricular mass index, calculated with the Devereux equation and indexed to body surface area, with left ventricular hypertrophy defined as a mass index above 115 g/m2 in men and above 95 g/m2 in women. Anemia was classified by World Health Organization criteria: hemoglobin below 13 g/dL in men and below 12 g/dL in women, with moderate anemia defined as hemoglobin 8 to 11 g/dL and severe anemia as hemoglobin below 8 g/dL.

Anemia was common in both settings. Its prevalence was 22.9 percent in Tanzania, where 3.5 percent of participants had severe anemia, 10.9 percent moderate and 8.5 percent mild, and 31.9 percent in Haiti, where 1.5 percent had severe anemia, 10.3 percent moderate and 20.1 percent mild. Most anemic participants were women, 92 percent in Tanzania and 76 percent in Haiti, and in the Tanzanian cohort most were people with HIV, accounting for 146 of the anemic participants, or 63.8 percent.

In both cohorts, blood pressure and body mass index fell stepwise with increasing anemia severity, and the prevalence of reduced kidney function was similar across anemia categories. Yet when the team modeled the relationship between anemia and left ventricular mass index, adjusting for age, sex, systolic blood pressure, HIV status and body mass index, moderate and severe anemia emerged as independent predictors of a heavier left ventricle. In Tanzania, moderate anemia was associated with an increase of 4.6 g/m2 and severe anemia with 20.3 g/m2, while in Haiti the corresponding figures were 9.5 g/m2 and 33.5 g/m2. Mild anemia showed no significant difference from no anemia.

In the combined analysis of both countries, which additionally adjusted for cohort differences, moderate anemia was associated with a left ventricular mass index increase of 8.4 g/m2 and severe anemia with an increase of 29.7 g/m2, both statistically significant. The authors note that this magnitude is clinically meaningful: each 10 g/m2 incremental increase in left ventricular mass index has been independently associated with a 33 percent increased risk of cardiovascular disease in prior research. The association was consistent across the two geographically and demographically distinct populations, which the investigators interpret as evidence of generalizability across diverse low- and middle-income settings.

The pattern of echocardiographic changes pointed to a specific cardiac phenotype. Beyond the higher left ventricular mass index, anemia was associated with significantly higher cardiac index, stroke volume index, left ventricular end diastolic volume index, left ventricular internal dimension in diastole, average E/e′, a measure of left ventricular filling pressure, and left atrial volume index, the last available only in the Tanzanian cohort. There was no association with heart rate, ejection fraction or relative wall thickness. Taken together, the investigators describe this as high-output cardiac hypertrophy: elevated stroke volume and cardiac output with ventricular dilation and eccentric remodeling, a pattern consistent with chronic volume overload from anemia. The elevated average E/e′ and left atrial volume suggest a possible progression toward diastolic dysfunction, though the authors caution that longitudinal studies are needed to confirm whether this phenotype progresses to clinical heart failure.

The population-level stakes were quantified using the population attributable fraction, estimated with multivariate models that fitted anemia and hypertension simultaneously. In Tanzania, 39.8 percent of left ventricular hypertrophy cases were associated with hypertension and 18.2 percent with moderate to severe anemia. In Haiti, the corresponding figures were 24.3 percent and 9.1 percent. Among people with HIV in the Tanzanian cohort, the picture reversed: 34.4 percent of left ventricular hypertrophy was associated with moderate or severe anemia, exceeding the 25.9 percent attributed to hypertension. In analyses restricted to women, 20.8 percent of hypertrophy in Tanzania and 11.9 percent in Haiti were associated with moderate to severe anemia.

The findings carry particular weight for two groups. Women in low- and middle-income countries bear a disproportionate burden of anemia, driven by iron loss and demand from menstruation, pregnancy and childbirth, and the authors note that anemia might contribute to peripartum cardiomyopathy when the cardiac stress of pregnancy compounds chronic volume overload. For people with HIV, who face roughly a two-fold higher risk of cardiovascular disease even after accounting for traditional risk factors, anemia was common in this study despite nearly all participants being on stable antiretroviral therapy with integrase-inhibitor-based regimens and 97.2 percent being virologically suppressed. The authors suggest anemia-induced hypertrophy may help explain elevated cardiovascular rates in people with HIV who lack conventional risk factors such as hypertension.

The study has clear limits. Its cross-sectional design cannot establish that anemia causes the cardiac changes, and the cause of anemia in the participants, whether iron deficiency, chronic inflammation from HIV infection or something else, was not determined, with different etiologies potentially producing distinct cardiac remodeling. The Haiti echocardiography subset was selected toward more severe cardiac and vascular pathology, and although probability weighting was used, the generalizability of the Haitian estimates may be constrained relative to an unselected cohort. The authors call for longitudinal observational studies and clinical trials to determine whether improved anemia detection and treatment can prevent symptomatic heart failure. In the meantime, they argue that screening for anemia alongside traditional cardiovascular risk factors, particularly in women and people with HIV, and integrating anemia care into platforms such as routine HIV and antenatal services, deserves consideration from clinicians and policymakers in affected regions.

Subject of Research: The association between anemia severity and high-output cardiac hypertrophy among adults in Tanzania and Haiti

Article Title: Anemia and high-output cardiac hypertrophy in Tanzania and Haiti: a cross-sectional analysis

Article References: Rouzier, V., Ruselu, G., Willkens, M., Yan, L. D., Cichowitz, C., Ogyu, A., Garbindi, A., Kisigo, G., Issarow, B., Sufra, R., Etyang, A., Pape, J. W., Devereux, R. B., McNairy, M., Kapiga, S., Peck, R., & Lee, M. H. (2026). Anemia and high-output cardiac hypertrophy in Tanzania and Haiti: a cross-sectional analysis. BMC Global and Public Health, 4(1), Article 107. https://doi.org/10.1186/s44263-026-00330-6

Image Credits: AI Generated

DOI: 10.1186/s44263-026-00330-6

Keywords: anemia, left ventricular hypertrophy, echocardiography, cardiovascular disease, Tanzania, Haiti, HIV, high-output cardiac state, low- and middle-income countries, cross-sectional study, population attributable fraction, modifiable risk factor