Key result
Coronary flow reserve was independently associated with peak oxygen uptake (standardized coefficient 1.98, p=0.05) in heart failure patients, suggesting it partly mediates the link between insulin resistance and exercise intolerance.
Cross-Sectional (n=39)
No
Effect estimate: SC 1.98
p-value: p=0.05
This study suggests that the association between insulin resistance and exercise intolerance in heart failure patients is partly mediated by reduced coronary flow reserve.
CFR may mediate insulin resistance effects on exercise capacity in HF; leaves open causal role and need for interventional confirmation.
BACKGROUND: Insulin resistance has been linked to exercise intolerance in heart failure patients. The aim of this study was to assess the potential role of coronary flow reserve (CFR), endothelial function and arterial stiffness in explaining this linkage. METHODS: 39 patients with LVEF < 35% (median LV ejection fraction (LVEF) 31 (interquartile range (IQ) 26-34), 23/39 of ischemic origin) underwent echocardiography with measurement of CFR. Peak coronary flow velocity (CFV) was measured in the LAD and coronary flow reserve was calculated as the ratio between CFV at rest and during a 2 minutes adenosine infusion. All patients performed a maximal symptom limited exercise test with measurement of peak oxygen uptake (VO(2)peak), digital measurement of endothelial function and arterial stiffness (augmentation index), dual X-ray absorptiometry scan (DEXA) for body composition and insulin sensitivity by a 2 hr hyperinsulinemic (40 mU/min/m(2)) isoglycemic clamp. RESULTS: Fat free mass adjusted insulin sensitivity was significantly correlated to VO(2)peak (r = 0.43, p = 0.007). Median CFR was 1.77 (IQ 1.26-2.42) and was correlated to insulin sensitivity (r 0.43, p = 0.008). CFR (r = 0.48, p = 0.002), and arterial stiffness (r = -0.35, p = 0.04) were correlated to VO(2)peak whereas endothelial function and LVEF were not (all p > 0.15). In multivariable linear regression adjusting for age, CFR remained independently associated with VO2peak (standardized coefficient (SC) 1.98, p = 0.05) whereas insulin sensitivity (SC 1.75, p = 0.09) and arterial stiffness (SC -1.17, p = 0.29) were no longer associated with VO2peak. CONCLUSIONS: The study confirms that insulin resistance is associated with exercise intolerance in heart failure patients and suggests that this is partly through reduced CFR. This is the first study to our knowledge that shows an association between CFR and exercise capacity in heart failure patients and links the relationship between insulin resistance and exercise capacity to CFR.
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Snoer et al. (2012) conducted a cross-sectional in Heart failure (n=39). Coronary flow reserve and insulin sensitivity was evaluated on Association between coronary flow reserve and peak oxygen uptake (VO2peak) (SC 1.98, p=0.05). Coronary flow reserve was independently associated with peak oxygen uptake (standardized coefficient 1.98, p=0.05) in heart failure patients, suggesting it partly mediates the link between insulin resistance and exercise intolerance.
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