Publications

STUDY OBJECTIVE

Infarct size is a strong predictor of outcomes after ST elevation myocardial infarction (STEMI). Circulating fibrocytes are bone marrow-derived progenitor cells associated with fibrotic processes. We tested whether fibrocytes correlate with infarct size in STEMI patients treated with primary percutaneous coronary intervention (PCI).

DESIGN

Prospective observational study.

SETTING

Academic medical center.

PARTICIPANTS

Subjects with STEMI treated with primary PCI.

INTERVENTIONS

Peripheral blood draw and cardiac magnetic resonance imaging (CMR).

MAIN OUTCOME MEASURE

Correlation of fibrocyte levels with infarct size.

METHODS

Peripheral blood fibrocytes were quantified at discharge from STEMI hospitalization and at 6 months follow-up using flow cytometry. Infarct size was determined within 2 weeks of discharge and at 6 months follow-up using late gadolinium enhancement on CMR.

RESULTS

Among 14 patients (median age 54 years, 79% men) with STEMI, there was a statistically significant positive correlation between fibrocyte levels at 6 months and 6-month infarct size on CMR (r = 0.58, p = 0.031). In addition, there was positive correlation between peak troponin I level (r = 0.85, p < 0.001), and white blood cell count (r = 0.55, p = 0.042) during the hospital stay and 6-month infarct size on CMR.

CONCLUSIONS

Circulating fibrocytes measured 6 months after STEMI positively correlate with 6-month infarct size assessed by CMR.

South Africa is a middle-income country with high levels of income inequality and a rapidly aging population and increasing dementia prevalence. Little is known about which risk factors for dementia are important and how they differ by social determinants of health as well as key demographic characteristics such as sex and wealth. We sought to calculate the population attributable risks (PARs) for established potentially modifiable risk factors for dementia among these different groups. We obtained risk factor prevalence from population-based surveys for established dementia risk factors (diabetes, midlife hypertension, midlife obesity, physical inactivity, depression, smoking, low educational attainment, social isolation). We used relative risk estimates reported in previous meta-analyses and estimated PARs using Levin's formula and accounting for communality. We tested for one-way and two-way interactions by sex and wealth using Pearson's χ2. In stratified analyses, we performed tests for trend using logistic regression. The prevalence of established risk factors for dementia ranged from 5% for depression to 64% for low education. After accounting for communality, the risk factors contributing the greatest PAR were low education (weighted PAR 12%, 95% CI 7% to 18%), physical inactivity (9, 5-14%), and midlife hypertension (6, 5-14%). Together, 45% of dementia cases may be attributable to modifiable risk factors (95% CI 25-59%). We found significant interactions ( < 0.005) between sex, wealth, or both (sex wealth) and each risk factor except social isolation and physical activity. Low education was inversely associated with wealth in both male and female. The PAR for midlife hypertension, obesity, and diabetes was associated with increasing wealth, and was higher in female. In contrast, the PAR for smoking was higher in male (8% vs. 2%) and was associated with increasing wealth among female only. We found that either a strategy of large reductions in selected risk factors with the highest PAR (midlife hypertension, smoking, physical inactivity) or small reductions across all risk factors could potentially reduce dementia cases by as many as 250,000 by 2050. The potential impact on dementia risk by decreasing exposure to established dementia risk factors is large and differs by sex and social determinants of health like wealth. Risk factor PAR should inform national and local health policy dementia initiatives in South Africa including which risk factors to target in the whole population and which to target in high-risk groups for maximum public health benefit.