Quantification of circumferential, longitudinal, and radial global fractional shortening using steady-state free precession cines: a comparison with tissue-tracking strain and application in Fabry disease

Integration of longitudinal and circumferential strain predicts volumetric change across the cardiac cycle and differentiates patients along the heart failure continuum

BACKGROUND

Left ventricular (LV) circumferential and longitudinal strain provide important insight into LV mechanics and function, each contributing to volumetric changes throughout the cardiac cycle. We sought to explore this strain-volume relationship in more detail, by mathematically integrating circumferential and longitudinal strain and strain rate to predict LV volume and volumetric rates of change.

METHODS

Cardiac magnetic resonance (CMR) imaging from 229 participants from the Alberta HEART Study (46 healthy controls, 77 individuals at risk for developing heart failure [HF], 70 patients with diagnosed HF with preserved ejection fraction [HFpEF], and 36 patients with diagnosed HF with reduced ejection fraction [HFrEF]) were evaluated. LV volume was assessed by the method of disks and strain/strain rate were assessed by CMR feature tracking.

RESULTS

Integrating endocardial circumferential and longitudinal strain provided a close approximation of LV ejection fraction (EFStrain), when compared to gold-standard volumetric assessment (EFVolume: r = 0.94, P < 0.0001). Likewise, integrating circumferential and longitudinal strain rate provided a close approximation of peak ejection and peak filling rates (PERStrain and PFRStrain, respectively) compared to their gold-standard volume-time equivalents (PERVolume, r = 0.73, P < 0.0001 and PFRVolume, r = 0.78, P < 0.0001, respectively). Moreover, each integrated strain measure differentiated patients across the HF continuum (all P < 0.01), with the HFrEF group having worse EFStrain, PERStrain, and PFRStrain compared to all other groups, and HFpEF having less favorable EFStrain and PFRStrain compared to both at-risk and control groups.

CONCLUSIONS

The data herein establish the theoretical framework for integrating discrete strain components into volumetric measurements across the cardiac cycle, and highlight the potential benefit of this approach for differentiating patients along the heart failure continuum.

Left ventricular circumferential strain and coronary microvascular dysfunction: A report from the Women's Ischemia Syndrome Evaluation Coronary Vascular Dysfunction (WISE-CVD) Project

AIMS

Women with ischemia but no obstructive coronary artery disease (INOCA) often have coronary microvascular dysfunction (CMD). Left ventricular (LV) circumferential strain (CS) is often lower in INOCA compared to healthy controls; however, it remains unclear whether CS differs between INOCA women with and without CMD. We hypothesized that CS would be lower in women with CMD, consistent with CMD-induced LV mechanical dysfunction.

METHODS AND RESULTS

Cardiac magnetic resonance (cMR) images were examined from women enrolled in the Women's Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction Project. CS by feature tracking in INOCA women with CMD, defined as myocardial perfusion reserve index (MPRI) <1.84 during adenosine-stress perfusion cMR, was compared with CS in women without CMD. In a subset who had invasive coronary function testing (CFT), the relationship between CS and CFT metrics, LV ejection fraction (LVEF) and cardiovascular risk factors was investigated. Among 317 women with INOCA, 174 (55%) had CMD measured by MPRI. CS was greater in women with CMD compared to those without CMD (23.2 ± 2.5% vs. 22.1 ± 3.0%, respectively, P = 0.001). In the subset with CFT (n = 153), greater CS was associated with increased likelihood of reduced vasodilator capacity (OR = 1.33, 95%CI = 1.02-1.72, p = 0.03) and discriminated abnormal vs. normal coronary vascular function compared to CAD risk factors, LVEF and LV concentricity (AUC: 0.82 [0.73-0.96 95%CI] vs. 0.65 [0.60-0.71 95%CI], respectively, P = 0.007).

CONCLUSION

The data indicate that LV circumferential strain is related to and predicts CMD, although in a direction contrary with our hypothesis, which may represent an early sign of LV mechanical dysfunction in CMD.

Left ventricular diastolic dysfunction and exercise intolerance in obese heart failure with preserved ejection fraction

This study tested the hypothesis that early left ventricular (LV) relaxation is impaired in older obese patients with heart failure with preserved ejection fraction (HFpEF), and related to decreased peak exercise oxygen uptake (peak V̇o₂). LV strain and strain rate were measured by feature tracking of magnetic resonance cine images in 79 older obese patients with HFpEF (mean age: 66 yr; mean body mass index: 38 kg/m²) and 54 healthy control participants. LV diastolic strain rates were indexed to cardiac preload as estimated by echocardiography derived diastolic filling pressures (E/e'), and correlated to peak V̇o₂. LV circumferential early diastolic strain rate was impaired in HFpEF compared with controls (0.93 ± 0.05/s vs. 1.20 ± 0.07/s, P = 0.014); however, we observed no group differences in early LV radial or longitudinal diastolic strain rates. Isolating myocardial relaxation by indexing all three early LV diastolic strain rates (i.e. circumferential, radial, and longitudinal) to E/e' amplified the group difference in early LV diastolic circumferential strain rate (0.08 ± 0.03 vs. 0.13 ± 0.05, P < 0.0001), and unmasked differences in early radial and longitudinal diastolic strain rate. Moreover, when indexing to E/e', early LV diastolic strain rates from all three principal strains, were modestly related with peak V̇o₂ (R = 0.36, -0.27, and 0.35, respectively, all P < 0.01); this response, however, was almost entirely driven by E/e' itself, (R = -0.52, P < 0.001). Taken together, we found that although LV relaxation is impaired in older obese patients with HFpEF, and modestly correlates with their severely reduced peak exercise V̇o₂, LV filling pressures appear to play a much more important role in determining exercise intolerance.NEW & NOTEWORTHY Using a multimodal imaging approach to uncouple tissue deformation from atrial pressure, we found that left ventricular (LV) relaxation is impaired in older obese patients with HFpEF, but only modestly correlates with their severely reduced peak V̇o₂. In contrast, the data show a much stronger relationship between elevated LV filling pressures and exercise intolerance, refocusing future therapeutic priorities.

Loss of base-to-apex circumferential strain gradient assessed by cardiovascular magnetic resonance in Fabry disease: relationship to T1 mapping, late gadolinium enhancement and hypertrophy

BACKGROUND

Cardiac involvement is common and is the leading cause of mortality in Fabry disease (FD). We explored the association between cardiovascular magnetic resonance (CMR) myocardial strain, T1 mapping, late gadolinium enhancement (LGE) and left ventricular hypertrophy (LVH) in patients with FD.

METHODS

In this prospective study, 38 FD patients (45.0 ± 14.5 years, 37% male) and 8 healthy controls (40.1 ± 13.7 years, 63% male) underwent 3 T CMR including cine balanced steady-state free precession (bSSFP), LGE and modified Look-Locker Inversion recovery (MOLLI) T1 mapping. Global longitudinal (GLS) and circumferential (GCS) strain and base-to-apex longitudinal strain (LS) and circumferential strain (CS) gradients were derived from cine bSSFP images using feature tracking analysis.

RESULTS

Among FD patients, 8 had LVH (FD LVH+, 21%) and 17 had LGE (FD LGE+, 45%). Nineteen FD patients (50%) had neither LVH nor LGE (FD LVH- LGE-). None of the healthy controls had LVH or LGE. FD patients and healthy controls did not differ significantly with respect to GLS (- 15.3 ± 3.5% vs. - 16.3 ± 1.5%, p = 0.45), GCS (- 19.4 ± 3.0% vs. -19.5 ± 2.9%, p = 0.84) or base-to-apex LS gradient (7.5 ± 3.8% vs. 9.3 ± 3.5%, p = 0.24). FD patients had significantly lower base-to-apex CS gradient (2.1 ± 3.7% vs. 6.5 ± 2.2%, p = 0.002) and native T1 (1170.2 ± 37.5 ms vs. 1239.0 ± 18.0 ms, p < 0.001). Base-to-apex CS gradient differentiated FD LVH- LGE- patients from healthy controls (OR 0.42, 95% CI: 0.20 to 0.86, p = 0.019), even after controlling for native T1 (OR 0.24, 95% CI: 0.06 to 0.99, p = 0.049). In a nested logistic regression model with native T1, model fit was significantly improved by the addition of base-to-apex CS gradient (χ2(df = 1) = 11.04, p < 0.001). Intra- and inter-observer agreement were moderate to good for myocardial strain parameters: GLS (ICC 0.849 and 0.774, respectively), GCS (ICC 0.831 and 0.833, respectively), and base-to-apex CS gradient (ICC 0.737 and 0.613, respectively).

CONCLUSIONS

CMR reproducibly identifies myocardial strain abnormalities in FD. Loss of base-to-apex CS gradient may be an early marker of cardiac involvement in FD, with independent and incremental value beyond native T1.

Elevated Inflammatory Plasma Biomarkers in Patients With Fabry Disease: A Critical Link to Heart Failure With Preserved Ejection Fraction

Background Because systemic inflammation and endothelial dysfunction lead to heart failure with preserved ejection fraction, we characterized plasma levels of inflammatory and cardiac remodeling biomarkers in patients with Fabry disease ( FD ). Methods and Results Plasma biomarkers were studied in multicenter cohorts of patients with FD (n=68) and healthy controls (n=40). Plasma levels of the following markers of inflammation and cardiac remodeling were determined: tumor necrosis factor ( TNF ), TNF receptor 1 ( TNFR 1) and 2 ( TNFR 2), interleukin-6, matrix metalloprotease-2 ( MMP -2), MMP -8, MMP -9, galectin-1, galectin-3, B-type natriuretic peptide ( BNP ), midregional pro-atrial natriuretic peptide ( MR -pro ANP ), and globotriaosylsphingosine. Clinical profile, cardiac magnetic resonance imaging, and echocardiogram were reviewed and correlated with biomarkers. Patients with FD had elevated plasma levels of BNP , MR -pro ANP , MMP -2, MMP -9, TNF , TNFR 1, TNFR 2, interleukin-6, galectin-1, globotriaosylsphingosine, and analogues. Plasma TNFR 2, TNF , interleukin-6, MMP -2, and globotriaosylsphingosine were elevated in FD patients with left ventricular hypertrophy, whereas diastolic dysfunction correlated with higher BNP , MR -pro ANP , and MMP -2 levels. Patients with late gadolinium enhancement on cardiac magnetic resonance imaging had greater levels of BNP , MR -pro ANP , TNFR 1, TNFR 2, and MMP -2. Plasma BNP , MR -pro ANP , MMP -2, MMP -8, TNF , TNFR 1, TNFR 2, galectin-1, and galectin-3 were elevated in patients with renal dysfunction. Patients undergoing enzyme replacement therapy who have more severe disease had higher MMP -2, TNF , TNFR 1, TNFR 2, and globotriaosylsphingosine analogue levels. Conclusions Inflammatory and cardiac remodeling biomarkers are elevated in FD patients and correlate with disease progression. These features are consistent with a phenotype dominated by heart failure with preserved ejection fraction and suggest a key pathogenic role of systemic inflammation in FD .

Comparison of Cardiac Magnetic Resonance Imaging and Echocardiography in Assessment of Left Ventricular Hypertrophy in Fabry Disease

BACKGROUND

Cardiac hypertrophy in Fabry disease can be assessed using the left ventricular mass index (LVMI) with either echocardiography (LVMI-ECHO) or magnetic resonance imaging (LVMI-CMR).

METHODS

A retrospective case series of patients with Fabry disease in Alberta involved a cross-sectional analysis of 32 patients and a longitudinal analysis of 14 of these patients with at least 4 serial CMR measurements.

RESULTS

The cross-sectional analysis showed the mean LVMI-ECHO was 97.8 ± 26.0 g/m², which was higher compared with LVMI-CMR at 81.1 ± 26.9 g/m² with a mean bias of 16.7 g/m² (P < 0.001). In the longitudinal analysis, LVMI-ECHO was higher, with an estimated marginal mean of 96.21 ± 6.13 (mean ± standard error of the mean [SEM]) compared with 71.18 ± 5.99 for LVMI-CMR (P < 0.01; generalized estimating equations). There was an association between an increase in LVMI-CMR over time with the presence of cardiac fibrosis, and patients treated with enzyme replacement therapy (ERT) had slower increases than those without therapy. LVMI-ECHO failed to detect these associations owing to the higher variability and tendency to overestimate the LVMI.

CONCLUSIONS

We propose the preferred method for measuring LVMI is CMR in patients with Fabry disease.

Evaluation of left ventricular strain in patients with dilated cardiomyopathy

Objective Dilated cardiomyopathy (DCM) can cause structural and functional changes in the left ventricle (LV). In this study, we evaluated whether cardiac magnetic resonance tissue-tracking (MR-TT) can be applied to the detection of LV abnormalities in patients with DCM. Methods We used MR-TT to analyze the global peak radial strain (GPRS), global peak circumferential strain (GPCS), and global peak longitudinal strain (GPLS) in every segment of the LV in 23 patients with DCM and 25 controls. The LV ejection fraction was also measured as a function indicator. Results Compared with the controls, the GPRS, GPCS, and GPLS were significantly reduced in patients with DCM, indicating global LV function impairment in all directions. We also identified a significant linear correlation between the GPRS, GPCS, and GPLS and the LV ejection fraction, indicating that LV function relies on coordinated wall motion from all directions. Moreover, we found that patients with DCM had a significantly reduced magnitude of the PRS, PCS, and PLS in most segments at different levels, indicating impaired myocardial function in most LV regions. Conclusions Our results demonstrate that LV myocardial strain in patients with DCM can be sensitively detected by MR-TT (not only the global LV function changes but also the segmental strain), which can help to identify the injured segment at an early stage and guide clinical treatment.

Increased left ventricular extracellular volume and enhanced twist function in type 1 diabetic individuals

Individuals with type 1 diabetes (T1D) characteristically have high glycemic levels that over time can result in reactive fibrosis and abnormalities in myocardial function. T₁ mapping with magnetic resonance imaging (MRI) can estimate the extent of reactive fibrosis by measurement of the extracellular volume fraction (ECV). The extent of alterations in the ECV and associated changes in left ventricular (LV) function and morphology in individuals with T1D is unknown. Fourteen individuals with long-term T1D and 14 sex-, age-, and body mass index-matched controls without diabetes underwent MRI measurement of myocardial T₁ and ECV values as well as LV function and morphology. Ventricular mass, volumes, and global function (LVEF and circumferential/longitudinal/radial strain) were similar in those with T1D and controls. However, those with T1D had larger myocardial ECV (22.1 ± 1.8 vs. 20.1 ± 2.1, P = 0.008) and increased native (noncontrast) myocardial T₁ values (1,211 ± 44 vs. 1,172 ± 43 ms, P < 0.001) as compared with controls. Both the ECV and native T₁ values significantly correlated with several components of torsion and circumferential-longitudinal shear strain (E_cl, the shear strain component associated with twist). Individuals with T1D had increased systolic torsion (P = 0.035), systolic torsion rate (P = 0.032), peak E_cl (P = 0.001), and rates of change of systolic (P = 0.007) and diastolic (P = 0.007) E_cl Individuals with T1D, with normal structure, LVEF, and strain, have increased extracellular volume and increased native T₁ values with associated augmented torsion and E_cl These measures may be useful in detecting the early stages of diabetic cardiomyopathy and warrant larger prospective studies.NEW & NOTEWORTHY Individuals with type 1 diabetes, with normal left ventricular structure and function (ejection fraction and strain), have signs of interstitial fibrosis, measured with MRI as increased extracellular volume fraction and increased native myocardial T₁, which significantly correlated with a number of measures of augmented left ventricular twist function. These measures may be useful in detecting the early stages of diabetic cardiomyopathy.

The Relationship Between Left Ventricular Wall Thickness, Myocardial Shortening, and Ejection Fraction in Hypertensive Heart Disease: Insights From Cardiac Magnetic Resonance Imaging

Hypertensive heart disease is often associated with a preserved left ventricular ejection fraction despite impaired myocardial shortening. The authors investigated this paradox in 55 hypertensive patients (52±13 years, 58% male) and 32 age- and sex-matched normotensive control patients (49±11 years, 56% male) who underwent cardiac magnetic resonance imaging at 1.5T. Long-axis shortening (R=0.62), midwall fractional shortening (R=0.68), and radial strain (R=0.48) all decreased (P<.001) as end-diastolic wall thickness increased. However, absolute wall thickening (defined as end-systolic minus end-diastolic wall thickness) was maintained, despite the reduced myocardial shortening. Absolute wall thickening correlated with ejection fraction (R=0.70, P<.0001). In multiple linear regression analysis, increasing wall thickness by 1 mm independently increased ejection fraction by 3.43 percentage points (adjusted β-coefficient: 3.43 [2.60-4.26], P<.0001). Increasing end-diastolic wall thickness augments ejection fraction through preservation of absolute wall thickening. Left ventricular ejection fraction should not be used in patients with hypertensive heart disease without correction for degree of hypertrophy.

Reduced Right Ventricular Native Myocardial T1 in Anderson-Fabry Disease: Comparison to Pulmonary Hypertension and Healthy Controls

AIMS

Anderson-Fabry disease (AFD) is characterized by progressive multiorgan accumulation of intracellular sphingolipids due to α-galactosidase A enzyme deficiency, resulting in progressive ventricular hypertrophy, heart failure, arrhythmias, and death. Decreased native (non-contrast) left ventricular (LV) T1 (longitudinal relaxation time) with MRI discriminates AFD from healthy controls or other presentations of concentric hypertrophy, but the right ventricle (RV) has not been studied. The aims of the current study were to evaluate native RV T1 values in AFD, with a goal of better understanding the pathophysiology of RV involvement.

METHODS AND RESULTS

Native T1 values were measured in the inferior RV wall (RVI), interventricular septum (IVS), and inferior LV (LVI) in patients with AFD, patients with pulmonary hypertension, who provided an alternative RV pathological process for comparison, and healthy controls. A minimum wall thickness of 4 mm was selected to minimize partial volume errors in tissue T1 analysis. T1 analysis was performed in 6 subjects with AFD, 6 subjects with PH, and 21 controls. Native T1 values were shorter (adjusted p<0.05 for all comparisons), independent of location, in subjects with AFD (RVI-T1 = 1096±49 ms, IVS-T1 = 1053±41 ms, LVI-T1 = 1072±44 ms) compared to both PH (RVI-T1 = 1239±41 ms, IVS-T1 = 1280±123 ms, LVI-T1 = 1274±57 ms) and HC (IVS-T1 = 1180±60 ms, LVI-T1 = 1183±45 ms). RVI measurements were not possible in controls due to insufficient wall thickness.

CONCLUSION

Native T1 values appear similarly reduced in the left and right ventricles of individuals with AFD and RV wall thickening, suggesting a common pathology. In contrast, individuals with PH and thickened RVs showed increased native T1 values in both ventricles, suggestive of fibrosis.

Normal left-atrial structure and function despite concentric left-ventricular remodelling in a cohort of patients with Anderson-Fabry disease

AIMS

Anderson-Fabry Disease (AFD) is an important cause of cardiomyopathy characterized by concentric left-ventricular hypertrophy (LVH). We evaluated the extent of left-atrial (LA) structural and functional remodelling in this group of patients given that LA remodelling is a marker of adverse outcomes in the presence of LVH.

METHODS AND RESULTS

Clinical profiles were obtained and cardiac MRI was performed in cohorts of patients with AFD (n = 31), healthy controls (n = 23), and a positive control cohort with known concentric remodelling and LVH (CR/H, n = 21). Of patients with AFD, 58% were on enzyme-replacement therapy (ERT), 84% were on renin-angiotensin system antagonism, and 65% were on statins. Despite a similar increase in LV mass index in the AFD when compared with the CR/H cohort, mean LA volumes for the AFD group were similar to those seen in the healthy control group. Following from this, we observed that the percentage contribution to LV stroke volume due to elastic/passive and active LA emptying was similar in the AFD and healthy control groups, while passive emptying was significantly lower in the CR/H group. The consequences of LVH in the AFD cohort were manifested in atrioventricular uncoupling, whereby the extent of elastic/passive and active LA emptying was not a function of the extent of longitudinal movement of the mitral annular plane, as it was in healthy control subjects.

CONCLUSION

Left-atrial structure and function were relatively normal in our cohort of patients with AFD, who were also judiciously treated with a contemporary strategy that includes renin-angiotensin system antagonism, statins, and ERT.