Abstract 9416: Monocyte Subsets and Exercise Capacity in Patients With Atrial Fibrillation With Preserved Left Ventricular Function

Introduction: Monocytes play important roles in inflammation, angiogenesis and tissue repair in cardiovascular disease. This study examined differences in monocyte subset numbers, subsequent markers of inflammation and cardiac fibrosis in patients with permanent atrial fibrillation and preserved left ventricular function with regards to peak exercise capacity (cardiopulmonary exercise testing and 6 minute walk test), quality of life and hospitalisation. Furthermore, the effects of spironolactone vs placebo on the quantitative measurement of these potential biomarkers were assessed in a double blind randomised study over a 2 year period. Methods: Three monocyte subsets [CD14++CD16-CCR2+ (Mon1), CD14++CD16+CCR2+ (Mon2) and CD14+CD16++CCR2- (Mon3)] were analysed by flow cytometry and ELISA to quantify makers of fibrosis in the form of Galectin 3, Type III Procollagen Peptide and Type I Procollagen Peptide. SPSS software was used to carry out statistical analysis of all 250 patients in the study cohort using stepwise multivariant linear regression analysis. Independent samples T testing between spironolactone and placebo groups were carried out. Results: Monocyte subsets CD16 Mon3 (p=0.001) and CD42 MPA3 (p=0.030) were found to be predictors of peak VO 2 . Comparison of monocyte subsets at end of study showed no differences between Mon1 (p=0.86), Mon2 (p=0.66) or Mon3 (p=0.81) subsets and their subsequent makers of inflammation and fibrosis between the treatment and placebo control group. This held true for further markers of cardiac fibrosis with regards to 6 minute walk test , quality of life assessment and hospitalisation. Conclusions: This study shows that monocyte subsets can be potential biomarkers of exercise capacity which in the form of cardiopulmonary testing is known to have morbidity and mortality implications. CD16 Mon3 were significantly related to beneficial outcomes with regards to a peak exercise capacity in respect to VO 2 max (higher CD16 Mon3 count associated with higher peak VO 2 performance). Spironolactone has no impact on primary or secondary outcome in this study.