Magnetic resonance imaging detects significant sex differences in human myocardial strain

Abstract

Background: The pathophysiology responsible for the significant outcome disparities between men and women with cardiac disease is largely unknown. Further investigation into basic cardiac physiological differences between the sexes is needed. This study utilized magnetic resonance imaging (MRI)-based multiparametric strain analysis to search for sex-based differences in regional myocardial contractile function.

Methods: End-systolic strain (circumferential, longitudinal, and radial) was interpolated from MRI-based radiofrequency tissue tagging grid point displacements in each of 60 normal adult volunteers (32 females).

Results: The average global left ventricular (LV) strain among normal female volunteers (n = 32) was significantly larger in absolute value (functionally better) than in normal male volunteers (n = 28) in both the circumferential direction (Male/Female = -0.19 ± 0.02 vs. -0.21 ± 0.02; p = 0.025) and longitudinal direction (Male/Female = -0.14 ± 0.03 vs. -0.16 ± 0.02; p = 0.007).

Conclusions: The finding of significantly larger circumferential and longitudinal LV strain among normal female volunteers suggests that baseline contractile differences between the sexes may contribute to the well-recognized divergence in cardiovascular disease outcomes. Further work is needed in order to determine the pathologic changes that occur in LV strain between women and men with the onset of cardiovascular disease.

Figure 1

MRI Motion Tracking. Tagged MRI images of the left ventricle are shown at end-diastole, mid-systole, and end-systole. Images are acquired approximately every 30 ms throughout the complete heart cycle. Tag lines are semi-automatically tracked through systole, and displacements are computed using a previously described and validated method [20].

Figure 2

Regional Circumferential Strain Comparison between Men and Women. Circumferential strain means with standard deviation bars of men and women are demonstrated. Adjusted p-values are as follows: Posteroseptal, p = .224; Anteroseptal, p = .002; Anterior, p = .027; Anterolateral, p = .439; Posterolateral, p = .394; Posterior, p = .542; Full LV, p = .025. Circumferential strain values were significantly greater in women than men both globally and in the anterior and anteroseptal walls.

Figure 3

Regional Longitudinal Strain Comparison between Men and Women. Longitudinal strain means (with standard deviation bars) of men and women are demonstrated. Adjusted p-values are as follows: Posteroseptal, p = .500 Anteroseptal, p = .237; Anterior, p = .004; Anterolateral, p = .005; Posterolateral, p = .006; Posterior, p = .041; Full LV, p = .007. Significant differences in longitudinal strain between the sexes were found globally and in the anterior, anterolateral and posterolateral walls.

Figure 4

Regional Radial Strain Comparison between Men and Women. Radial strain means (with standard deviation bars) of men and women are demonstrated. Adjusted p-values are as follows: Posteroseptal, p = .964; Anteroseptal, p = .140; Anterior, p = .995; Anterolateral, p = .966; Posterolateral, p = .968; Posterior, p = 1.000; Full LV, p = .789. No significant differences in regional or global radial strain values were observed between men and women.

Figure 5

Circumferential Strain Contour Plots in Men and Women. This left ventricular color contour plot graphically demonstrates the differences in circumferential strain between men and women. Average strain values for both groups were computed for a grid of 15,300 points within the ventricle. The differences between the male and female average values at corresponding points were used to generate the contour plot in this figure. All shades of blue in the plot indicate regions where strain values were larger (in absolute value) in women, while yellow and red colors indicate regions where strain values were larger in men.

Figure 6

Longitudinal Strain Contour Plots in Men and Women. This left ventricular color contour plot graphically demonstrates the differences in longitudinal strain between men and women. Average strain values for both groups were computed for a grid of 15,300 points within the ventricle. The differences between the male and female average values at corresponding points were used to generate the contour plot in this figure. All shades of blue in the plot indicate regions where strain values were larger (in absolute value) in women, while yellow and red colors indicate regions where strain values were larger in men.

Figure 7

Radial Strain Contour Plots in Men and Women. This left ventricular color contour plot graphically demonstrates the differences in radial strain between men and women. Average strain values for both groups were computed for a grid of 15,300 points within the ventricle. The differences between the male and female average values at corresponding points were used to generate the contour plot in this figure. All shades of blue in the plot indicate regions where radial strain values were larger in women, while yellow and red colors indicate regions where radial strain values in men exceeded those in women. There is no statistically significant difference in radial strain between men and women when compared on a regional or global left ventricular basis.

Figure 8

Mean Circumferential Maps in Men and Women. These left ventricular color contour plots graphically demonstrate circumferential strain averaged across the 28 males (left), and 32 females (right).

Figure 9

Mean Longitudinal Strain Maps in Men and Women. These left ventricular color contour plots graphically demonstrate longitudinal strain averaged across the 28 males (left), and 32 females (right).

Figure 10

Mean Radial Strain Maps in Men and Women. These left ventricular color contour plots graphically demonstrate radial strain averaged across the 28 males (left), and 32 females (right).