Impaired Exercise Capacity in Diabetic Patients after Coronary Bypass Surgery: Effects of Diastolic and Endothelial Function

Abstract

Objectives: The aims of this study were to clarify the influence of cardiac diastolic and peripheral vascular function on the exercise capacity of patients with coronary bypass surgery (CABG) and diabetes mellitus (DM) by tissue Doppler imaging (TDI) and flow-mediated vasodilatation (FMD), and to investigate interrelations between exercise capacity and LV diastolic function, endothelial function and biochemical parameters. Methods: We analyzed the exercise capacity, TDI at the mitral annulus and FMD in 51 uncomplicated first-time CABG survivors (23 DM) at an average interval of 21.6 ± 12.2 months after surgery. Results: Diabetics had lower E’, A’, VO₂peak, (a-v)O₂ difference, and higher E/E’ ratios (p < 0.05) than non-DM patients, but not FMD (p = 0.17). The A and E/E’ ratios correlated negatively with VO₂peak after age adjustment (r = –0.336, p = 0.024). In addition, HbA_1c, and triglyceride also correlated negatively with VO₂peak (r = –0.377, –0.307, respectively, p < 0.05). Conclusions: Diabetics after CABG had more advanced diastolic dysfunction and oxygen extraction impairment than non-DM. It suggests these factors could contribute to lower exercise capacity, risk of developing heart failure despite preserved systolic function and poorer long-term survival of diabetic patients after CABG.

Diastolic Heart Failure in Diabetics

“…The increased risk that diabetes poses for CHF in women compared with men was confirmed in the recent Heart and Estrogen Replacement Study [7] in which diabetes emerged as the strongest risk factor for CHF in women with coronary disease. This has not been shown in the study by Wu et al [1] . Thus, females suffer more often from CHF when compared with male diabetics.…”

“…In their study 'Impaired exercise capacity in diabetic patients after coronary bypass surgery: effects of diastolic and endothelial function', Wu et al [1] have demonstrated that diabetics after coronary artery bypass graft (CABG) had more advanced diastolic dysfunction and oxygen extraction impairment than non-diabetic patients.…”

Cardiovascular Phenotype in HFpEF Patients With or Without Diabetes

“…Decreased O 2 delivery may occur in diabetic patients with HFpEF due to a greater prevalence of anemia (a trend was seen in our data) or less vasodilator reserve due to autonomic dysfunction, an increased prevalence of peripheral vascular disease, or impaired endothelial function from oxidative stress, inflammation, and vasoconstriction (consistent with the biomarker elevations we observed in diabetic patients with HFpEF). Abnormalities in oxygen delivery and extraction have been observed in diabetic patients (28,29). …”

Continuous, non-invasive measurement of the haemodynamic response to submaximal exercise in patients with diabetes mellitus: evidence of impaired cardiac reserve and peripheral vascular response

“…Limitations on cardiac reserve and cardiac contractile function thus restrict the supply from meeting the demand imposed by exercise. In addition, microcirculatory deficits coupled with altered energetics limit the ability to meet the demand in exercising skeletal muscle in diabetics 15 16. Endothelial dysfunction and functional alterations of the microcirculation, on the other hand, precede morphological changes and contribute to an increased vascular permeability17 and an impaired endothelial vasodilatory response.…”