P5.28 THE EFFECT OF INSULIN RESISTANCE ON VENTRICULAR-ARTERIAL COUPLING; INSIGHTS FROM SEPARATED WAVE ANALYSIS IN YOUNG WOMEN WITH AND WITHOUT PCOS

Abstract

Objective: Polycystic ovary syndrome (PCOS) is characterised by obesity and a high prevalence of insulin resistance (IR) but this may not translate into increased cardiovascular events. The energy and timing of waves in large arteries may be quantified by separated wave analysis from wave intensity (WI) signals. This study characterised ventricular-arterial coupling (VAC) in three groups of young women (i) control (ii) IR (iii) PCOS+IR. Method: 143 women (16–45y) free from cardiovascular disease and diabetes were studied. IR was diagnosed if HOMA-IR was ≥2. PCOS was diagnosed using the Rotterdam criteria. WI was assessed by simultaneous recording of diameter-derived pressure and flow velocity signals from the CCA. Local wave speed (by water-hammer equation) was used to separate forward and backward waves as previously described. Backward waves were indexed by the integral of the preceding forward wave to characterise reflections independently of energy originating in the LV. Other key measures included central pulse wave velocity (PWV) from radial applanation tonometry and LV systolic and diastolic function by echo. Results: There were no between group differences in age, height, central PWV or echo measures of LV function. Control (n=44) IR (n=41) Control vs. IR p-value PCOS+IR (n=58) IR vs. PCOS+IR p-value Waist (cm) 78.6 90.2 <.001 97.8 .012 HOMA-IR 1.2 3.5 <.001 4.0 .020 Testosterone (nmol/L) 1.0 1.1 .370 1.6 .002 Heart rate (bpm) 67.0 72.9 .012 75.8 .163 FCW (W/m2) 11.4 14.7 <.001 13.1 .089 BCW/FCWint. (W/m2) 40.9 46.1 .037 39.8 .005 FEW (W/m2) 2.3 2.9 .002 2.5 .020 FEW duration (ms) 71.7 84.4 .031 76.8 .256 Time to FEW (ms) 333.1 305.3 .001 319.6 .073 Conclusion: In those without PCOS, IR was associated with increased amplitude forward compression (FCW) and expansion (FEW) waves actively generated by the LV and proportionally greater amplitude reflected waves (BCW/FCWint.). Proposed mechanisms include enhanced sympathetic nervous system activity by elevated endogenous insulin levels or obesity. PCOS+IR subjects had waves with amplitudes that more closely approximated control values, despite a worse risk profile.