Increased extracellular volume and altered mechanics are associated with LVH in hypertensive heart disease, not hypertension alone

Abstract

Objectives: The goal of this study was to assess the relationship among extracellular volume (ECV), native T1, and systolic strain in hypertensive patients with left ventricular hypertrophy (HTN LVH), hypertensive patients without LVH (HTN non-LVH), and normotensive controls.

Background: Diffuse myocardial fibrosis in HTN LVH patients, as reflected by increased ECV and native T1, may be an underlying mechanism contributing to increased cardiovascular risk compared with HTN non-LVH subjects and controls. Furthermore, increased diffuse fibrosis in HTN LVH subjects may be associated with reduced peak systolic and early diastolic strain rate compared with the other 2 groups.

Methods: T1 mapping was performed in 20 HTN LVH (mean age, 55 ± 11 years), 23 HTN non-LVH (mean age, 61 ± 12 years), and 22 control subjects (mean age, 54 ± 7 years) on a Siemens 1.5-T Avanto (Siemens Healthcare, Erlangen, Germany) using a previously validated modified look-locker inversion-recovery pulse sequence. T1 was measured pre-contrast and 10, 15, and 20 min after injection of 0.15 mmol/kg gadopentetate dimeglumine, and the mean ECV and native T1 were determined for each subject. Measurement of circumferential strain parameters were performed using cine displacement encoding with stimulated echoes.

Results: HTN LVH subjects had higher native T1 compared with controls (p < 0.05). HTN LVH subjects had higher ECV compared with HTN non-LVH subjects and controls (p < 0.05). Peak systolic circumferential strain and early diastolic strain rates were reduced in HTN LVH subjects compared with HTN non-LVH subjects and controls (p < 0.05). Increased levels of ECV and native T1 were associated with reduced peak systolic and early diastolic circumferential strain rate across all subjects.

Conclusions: HTN LVH patients had higher ECV, longer native T1 and associated reduction in peak systolic circumferential strain, and early diastolic strain rate compared with HTN non-LVH and control subjects. Measurement of ECV and native T1 provide a noninvasive assessment of diffuse fibrosis in hypertensive heart disease.

Keywords: T1 mapping; cardiac magnetic resonance; extracellular volume; hypertension; hypertensive heart disease; left ventricular hypertrophy; myocardial fibrosis.

Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1. Example of a T1 map

T1 maps pre-contrast (left) and post-contrast (right). T1 maps are generated from a collection of T1 images obtained at different inversion times during the same phase of the cardiac cycle.

Figure 2. Extracellular Volume of Gadolinium (ECV) among the three groups

Box-plot demonstrating the distribution of ECV among the three study groups. Boxes represent the 25th to 75th percentiles, and horizontal lines within the boxes represent the median values. HTN = Hypertension; LVH = Left ventricular hypertrophy; LVMI = Left ventricular mass index.

Figure 3. Correlation between ECV, Native T1 and LVMI

(a) Extracellular Volume vs. Left Ventricular Mass Index. Spearman correlation shows a positive association (Spearman rho = 0.26, p = 0.03) between ECV and LVMI. (b) Native T1 and Left Ventricular Mass Index. Spearman correlation shows a positive association (Spearman rho = 0.36, p = 0.03) between native T1 levels and LVMI. ECV= Extracellular Volume; HTN = Hypertension; LVH = Left ventricular hypertrophy; LVMI = Left ventricular mass index.

Figure 3. Correlation between ECV, Native T1 and LVMI

(a) Extracellular Volume vs. Left Ventricular Mass Index. Spearman correlation shows a positive association (Spearman rho = 0.26, p = 0.03) between ECV and LVMI. (b) Native T1 and Left Ventricular Mass Index. Spearman correlation shows a positive association (Spearman rho = 0.36, p = 0.03) between native T1 levels and LVMI. ECV= Extracellular Volume; HTN = Hypertension; LVH = Left ventricular hypertrophy; LVMI = Left ventricular mass index.

Figure 4. Circumferential strain and strain rates in the three groups

(a) Circumferential Strain Curves (b) Circumferential strain rates in the three study groups. Average circumferential and circumferential strain rates for the three groups are demonstrated. HTN = Hypertension; LVH = Left ventricular hypertrophy; Ecc = circumferential strain;

Figure 4. Circumferential strain and strain rates in the three groups

(a) Circumferential Strain Curves (b) Circumferential strain rates in the three study groups. Average circumferential and circumferential strain rates for the three groups are demonstrated. HTN = Hypertension; LVH = Left ventricular hypertrophy; Ecc = circumferential strain;

Figure 5. Correlation between ECV and Circumferential Strain, Strain Rate

(a) Peak Circumferential Strain vs. ECV. Pearson’s correlation shows a linear association between ECV and Peak circumferential strain (Pearson’s correlation coefficient of 0.26, p =0.05) (b) Average Early Diastolic Circumferential Strain Rate vs. ECV. Pearson’s correlation shows a linear association between ECV and Peak circumferential strain rate (Pearson’s correlation coefficient of −0.34, p =0.01). ECV = Extracellular Volume. Ave e′SR = Average Early Diastolic Circumferential Strain Rate.

Figure 5. Correlation between ECV and Circumferential Strain, Strain Rate

(a) Peak Circumferential Strain vs. ECV. Pearson’s correlation shows a linear association between ECV and Peak circumferential strain (Pearson’s correlation coefficient of 0.26, p =0.05) (b) Average Early Diastolic Circumferential Strain Rate vs. ECV. Pearson’s correlation shows a linear association between ECV and Peak circumferential strain rate (Pearson’s correlation coefficient of −0.34, p =0.01). ECV = Extracellular Volume. Ave e′SR = Average Early Diastolic Circumferential Strain Rate.

Figure 6. Correlation between Native T1 and Circumferential Strain, Strain Rate

(a) Peak Circumferential Strain vs. Native T1. Pearson’s correlation shows a linear association between native T1 levels and Peak circumferential strain (Pearson’s correlation coefficient of 0.44, p

Figure 6. Correlation between Native T1 and Circumferential Strain, Strain Rate

(a) Peak Circumferential Strain vs. Native T1. Pearson’s correlation shows a linear association between native T1 levels and Peak circumferential strain (Pearson’s correlation coefficient of 0.44, p