Relationships among Cynical Hostility, Metabolic Syndrome, and Cardiac Structure and Function in Multi-Ethnic Post-Myocardial Infarction Patients: A Structural Modeling Approach

of a dissertation at the University of Miami. Dissertation supervised by Neil Schneiderman, Ph.D. No. of pages in text (184) BACKGROUND: Risk factors associated with Metabolic Syndrome (MetS) have been implicated in cardiovascular disease (CVD) development and outcomes in both healthy and diseased populations. Few studies have investigated the relationships between psychological variables, MetS factors, and indices of cardiac structure and function among healthy individuals in a single conceptual model. No studies to date have analyzed these relationships in a single model among patients with extant CVD. METHODS: The present study examined associations between cynical hostility (CynHo), MetS factors, and cardiac structure and function in 186 multi-ethnic (81.7% Hispanic) post-myocardial infarction (MI) patients (69.4% men) with a mean age of 53.3 (SD=8.8) years. Structural equation modeling (SEM) was used to specify and test a model of MetS that had both good statistical fit and was based on theory, empirical evidence, and logical grounds. Primary MetS variables included waist circumference (WC), the homeostatic model of insulin resistance (HOMA-IR), glucose area under the curve (G-AUC), triglycerides (TRIG), high-density lipoprotein cholesterol (HDL-C), and diastolic blood pressures (DBP). Secondary MetS variables included plasminogen activator inhibitor-1 (PAI-1), a measure of fibrinolysis, and a latent inflammation variable comprised of C-reactive protein and interleukin-6. Cardiac function variables were fractional shortening (FS), a measure of cardiac contractility, E/A ratio, a measure of cardiac compliance, and rate-pressure product (RPP), a measure of myocardial oxygen demand. Cardiac structure variables were left ventricular mass index (LVMI), left ventricular posterior wall thickness at diastole (LVPWTd), and interventricular septal thickness at diastole (IVSTd) which together constituted the latent variable cardiac mass (CM). Cynical hostility (CynHo) was measured using a 13-item cynicism subscale of the Cook-Medley hostility scale. RESULTS: The final structural model had good model fit (χ (102)=100.65, p=0.52, CFI=1.00, RMSEA=0.00, and SRMR=0.04). In this model, direct paths were supported between WC and CM and all MetS factors except TRIG and G-AUC. WC was indirectly associated with DBP via CM. In addition, WC demonstrated indirect relationships with the cardiac function measures. The model supported positive direct paths between HOMA-IR and G-AUC, TRIG, and PAI-1, but not inflammation or HDL-C. With respect to cardiac function, HOMA-IR demonstrated a direct positive association with RPP and direct inverse associations with FS and E/A ratio. No direct paths were supported between other MetS variables except one between TRIG and HDL-C. CynHo had a direct positive relationship with HOMA-IR but none with WC. CONCLUSIONS: The relationships observed suggest that, similar to findings in healthy individuals, central adiposity and insulin resistance play a primary role in cardiac structural and functional impairment in post-MI patients. Unlike findings in healthy individuals, however, mediating relationships between other MetS factors and cardiac structural and functional impairment were not supported. Possible reasons underlying these findings are discussed. With respect to CynHo, our findings suggest that CynHo could promote the progression of metabolic dysfunction and cardiac disease via factors that influence the efficiency of glucose metabolism. Potential factors are discussed. Taken together, interventions for post-MI patients should take into account both direct and indirect effects of CynHo, central obesity, and IR on the progression of CVD in this population to reduce adverse outcomes and improve quality of life.