Body composition in elderly with myocardial infarction

Abstract

Abstract Background Body mass index may differ significantly from true fatness and cannot distinguish between excess body fat (BF) and an increase in fat-free mass (FFM) (a surrogate for skeletal muscle mass). Both FFM and BF have been shown to influence prognosis. Greater skeletal muscle strength enables better mobility and cardiorespiratory fitness, both of which are known prognostic factors for better outcome. There are no data on a possible association between body composition and prognosis in the elderly with myocardial infarction. Purpose We aimed to evaluate the effects of FFM and BF on 30-day and one-year all-cause mortality in patients ≥ 65 years of age with MI who underwent PCI. Methods This retrospective study was conducted at a tertiary referral hospital with a 24/7 PCI service. We screened 8348 MI patients, of whom 3946 were ≥ 65 years old. We formed four groups of patients with different body composition: HighFFM-LowBF (22 patients), HighFFM-HighBF (2165 patients), LowFFM-LowBF (1165 patients), and LowFFM-HighBF (594 patients). These groups were compared. Data were analyzed using descriptive statistics. Results The lowest mortality was observed in the HighFFM-LowBF group (4.5%), followed by the HighFFM-HighBF group (9.3%), LowFFM-LowBF and LowFFM-HighBF (13.0% and 13.1%, respectively; p=0.002 (Figure 1). After one year, mortality was 18.2% in the HighFFM-LowBF group, 16.1% in the HighFFM-HighBF group, 22.6% in the LowFFM-LowBF group, and 26.4% in the LowFFM-HighBF group; p< 0.0001. (Figure 2). After adjustment for confounders, body composition groups were not associated with 30-day mortality (p=0.14), but were independently associated with one-year mortality risk (p=0.012). Conclusion Our result suggests that body composition is important in elderly patients with MI. We found that elderly patients with greater FFM (≈ muscle mass) survived better. The highest mortality was observed in sarcopenic obese elderly (low muscle mass and high body fat percentage).All-cause mortality in 30 daysOne-year all-cause mortality