July 18, 2018Open Access
Prognostic implication of monocytes in atrial fibrillation: The West Birmingham Atrial Fibrillation Project
Key Result
The highest quartile of monocyte counts (≥580 per μL) was independently associated with an increased risk of all-cause death (HR 1.64) and major adverse cardiovascular events (HR 1.58) in patients with atrial fibrillation.
Study Design
Type
Observational (n=881)
Multicenter
Yes
Structured PICO
Do high monocyte counts predict mortality, MACE, SSE, and major bleeding in patients with atrial fibrillation?
P
Population
881 patients with atrial fibrillation (AF)
I
Intervention
High monocyte counts (highest quartile, ≥580 μL)
C
Comparator
Lower monocyte counts (other quartiles, <580 μL)
O
Outcome
All-cause death, major adverse cardiovascular events (MACE), stroke, TIA or other systemic embolism (SSE), and major bleedinghard clinical
High monocyte counts (≥580 μL) independently predict increased long-term risk of mortality, MACE, and major bleeding in patients with atrial fibrillation.
Main Result
Effect estimate: HR 1.64 (95% CI 1.31-2.05)
p-value: p=<0.001
Limitations
- Possible effects of various co-morbidities affecting monocyte counts have not been analysed.
- Observational analysis without mechanistic insights into molecular mechanisms.
- Possible selection bias due to exclusion of patients with no full blood count tested during routine assessment.
- Medication modifications during follow-up may not have been fully captured.
Abstract
BACKGROUND AND OBJECTIVES: High monocyte counts are related to adverse outcomes in cardiovascular disease. Their role in prognostication in patients with atrial fibrillation (AF) is unknown. We investigated whether monocyte counts are useful as a marker of prognosis in patients with AF. METHODS: Monocyte counts were obtained from blood samples in 881 AF patients. Study outcomes were (i) all-cause death; (ii) major adverse cardiovascular events; (iii) stroke, TIA or other systemic embolism (SSE); and (iv) major bleeding. RESULTS: Median follow up was 7.2 years; 44% of patients died, 48% developed MACE; 9% had SSE and 5% had major bleeding. On Cox regression, after adjustment for CHA2DS2-VASc score, the highest quartile of monocyte counts (i.e., ≥580 μL vs. other quartiles) was associated with increased risk of death (hazard ratio HR 1.64, 95% confidence interval CI 1.31-2.05, p<0.001) and MACE (HR 1.58, 95% CI 1.28-1.96, p<0.001). Persistent monocyte levels ≥580 per μL during follow up were associated with further increase in risk of death (HR 1.52, 95% CI 1.10-2.11, p = 0.01) and MACE (HR 1.54, 95% CI 1.13-2.09, p = 0.006). Persistent monocyte levels ≥580 per μL during were associated with a significant increase in major bleeding events (HR 2.77, 95% CI 1.36-5.67, p = 0.005, after adjustment for HAS-BLED score). CONCLUSION: High monocyte counts independently predict the occurrence of MACE, major bleeding and mortality, but not SSE. Understanding the pathophysiological mechanisms involved would help understand the relationships between monocytes, and adverse thrombotic and bleeding outcomes in AF patients.