Does Metabolic Syndrome Influence Outcome Following Percutaneous Coronary Intervention?

In this issue of Angiology, Hu et al report the relationship between metabolic syndrome (MetS) and the outcome following drug-eluting stent (DES) implantation in Chinese patients (n 1⁄4 1224) with coronary heart disease (CHD). After a mean follow-up of 35.4 months, patients with MetS had a significantly higher incidence of all-cause death and major adverse cardiovascular events (MACE) compared with patients without MetS (P < .001). Dysglycemia at the time of stenting predicted increased all-cause mortality, while hypertension and dysglycemia predicted increased incidence of MACE. Furthermore, the combination of type 2 diabetes mellitus (T2DM) with MetS was associated with a worse prognosis than MetS alone. Patients with T2DM have a greater risk of vascular events and poor outcome following coronary revascularization with stenting using bare metal stents (BMS) compared with patients who do not have T2DM. However, this interpretation has been challenged by the use of DES instead of BMS. Similarly, an increased vascular risk has been linked with MetS, but the outcome after coronary stenting for CHD is not well documented. Therefore, Hu et al provide useful information regarding both the role of MetS and glycemia following coronary stenting using DES. There are several topics of interest in this field that we will address in this editorial. The results of any study involving MetS will undoubtedly depend on which definition of this syndrome is used. We reported significant differences in the prevalence of MetS and associated vascular disease as well as in the calculated vascular risk depending on the definition used. We also showed, in agreement with Hu et al, that MetS þ T2DM was associated with more vascular disease than MetS alone. Agreement between studies may improve if the 2009 consensus definition of MetS becomes widely accepted. There is emerging evidence supporting the use of ‘‘statin loading’’ pre-percutaneous coronary intervention (PCI). This does not seem to have been carried out by Hu et al probably because it is not currently a universally implemented procedure. There is also evidence that ‘‘getting to low-density lipoprotein cholesterol (LDL-C) target’’ is important for statin treatment. The mean LDL-C levels of 112 mg/dL (2.9 mmol/L) reported in the study by Hu et al is above target for high-risk patients (ie, 70-100 mg/dL; 1.8-2.6 mmol/L). However, this may be because the diagnosis of CHD was only confirmed after angiography. Whether similar adverse effects of MetS and/or T2DM are valid for interventions involving other arteries (eg, carotid and renal artery stenting or radial catheterization) remains to be established. In this context, there is evidence that patients with MetS undergoing carotid or renal artery stenting have a worse outcome than those without Mets. Furthermore, ‘‘statin loading’’ has been proposed to counter the inflammatory response after radial catheterization for coronary angiography. Clearly, there is a need to assess whether PCI is inferior to coronary artery bypass grafting (CABG) not only in patients with T2DM but also those with MetS without T2DM. DES use as well as other measures (eg, statin loading,, achieving LDL-C targets, aggressive antiplatelet therapy, control of hypertension, and smoking cessation) may further improve outcomes after stenting in these patients.