RELATIONSHIP BETWEEN AGE AND DIASTOLIC BLOOD PRESSURE TO CHANGES IN MYOCARDIAL OXYGENATION AS ASSESSED BY CARDIOVASCULAR MAGNETIC RESONANCE

Abstract

myocardial apoptosis, necrosis, collagen deposition and interstitial fibrosis. These may result in myocardial stiffness and alteration of myocardial extracellular volume fraction (ECV). In this pilot study, we hypothesize that CMR-determined LV diastolic dysfunction in diabetic patients is associated with increased ECV measured by T1 mapping. METHODS: 17 DM patients (6 males, age 63 10 years old) without macrovascular diseases were examined on a 1.5T MR system. LV systolic and diastolic function was determined using a short-axis SSFP stack, T1 map and average LV myocardium T1 at preand post-contrast was derived from a T1 prep or a modified Look-Locker sequence performed in a mid-LV level. Post-contrast late gadolinium enhancement (LGE) CMR was performed 15 minutes post injection of GdDTPA. LV systolic function and LGE determination used commercial software CMR42. LV diastolic functional parameters including peak filling rate (PFR) and time to peak filling rate (TPFR) were calculated using MASS software and were blinded to T1 analysis. T1 calculation used CMR42 or a customized Matlab code. Myocardial ECV 1⁄4 (1-haematocrit) (DR1myocardium/DR1blood). Increased ECV was defined as ECV > 30%. RESULTS: The average LV functional parameters in 17 subjects were in the normal range (LVEF1⁄461 6%, LVESV1⁄445 17 ml, LVEDV1⁄4113 33 ml, LVSV1⁄468 19 ml, LVM1⁄4103 25 g). No focal LGE was observed in this patient cohort. 8 of 17 subjects had ECV> 30% (ECV1⁄438 9%) and the other 7 subjects had ECV 0.05) in LV systolic functional parameters of LVEF, LVESV, LVEDV, LVSV and LVM between the increased ECV and normal ECV group. However, a statistically significant difference (P<0.05) was observed among diastolic functional parameters of TPFR and PFR, with significantly longer TPFR (344 148 vs.156 32 ms) and lower PFR (220 50 vs. 295 74 ml/s) observed in the increased ECV group. Also a statistically significant difference (P<0.05) was observed in pre-contrast T1 measurements. CONCLUSION: Increased ECV was observed in diabetic patients with preserved systolic function and this was associated with altered LV diastolic function. The increased ECV may indicate the presence of diffuse interstitial fibrosis and myocardial stiffness, thus limiting the LV diastolic relaxation.