Assessment of Right-Sided Heart Failure in Patients with Dilated Cardiomyopathy using Magnetic Resonance Relaxometry of the Liver

Hepatic Tissue Alterations in ST-Elevation Myocardial Infarction: Determinants and Prognostic Implications

BACKGROUND

The presence and clinical significance of hepatic tissue alterations as assessed by cardiac magnetic resonance imaging in patients with ST-segment-elevation myocardial infarction (STEMI), are unclear. This study aimed to investigate associations of hepatic T1 patterns with myocardial tissue damage and clinical outcomes in patients suffering from STEMI.

METHODS

We analyzed 485 patients with STEMI treated with percutaneous coronary intervention who were enrolled in the prospective MARINA STEMI study (Magnetic Resonance Imaging In Acute ST-Elevation Myocardial Infarction). Myocardial function and left and right ventricular (RV) infarct characteristics were assessed by cardiac magnetic resonance within the first week after STEMI. Native hepatic T1 times and extracellular volume were evaluated from standard cardiac T1 maps at baseline and 4 months thereafter.

RESULTS

Median hepatic T1 times were 559 ms (interquartile range, 514-605) at baseline and decreased to 542 ms (interquartile range, 507-577) at 4 months (P<0.001). Hepatic T1 times at baseline were independently associated with female sex (β 0.116; P=0.008), hyperlipidemia (β -0.116; P=0.008), and myocardial tissue damage (infarct size: β 0.178; P<0.001; microvascular obstruction: β 0.193; P<0.001; RV infarction: β 0.161; P<0.001). Determinants of hepatic T1 times at 4 months were female sex (β 0.123; P=0.002), multivessel disease (β 0.121; P=0.002), N-terminal pro-B-type natriuretic peptide (β 0.101; P=0.010), RV infarction (β 0.501; P<0.001), and RV end-systolic volume index (β 0.087; P=0.031). Patients without a decrease exhibited a higher frequency of major adverse cardiovascular events (13% versus 5%; P=0.003). Hepatic T1 times at baseline (hazard ratio, 1.87 [95% CI, 1.40-2.50]; P<0.001), 4 months (hazard ratio, 2.69 [95% CI, 2.15-3.36]; P<0.001), and hepatic extracellular volume at 4 months (hazard ratio, 1.59 [95% CI, 1.33-1.90]; P<0.001) were associated with major adverse cardiovascular events. After adjustment for univariable associates, only hepatic T1 times at 4 months were independently associated with adverse outcomes (hazard ratio, 2.86 [95% CI, 1.99-4.12]; P<0.001).

CONCLUSIONS

Hepatic tissue alterations determined by T1 mapping were associated with female sex, hyperlipidemia, multivessel disease, N-terminal pro-B-type natriuretic peptide, and left and RV myocardial tissue damage. These alterations can persist into the chronic phase after STEMI and indicate a worse clinical outcome.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT04113356.

T1 Mapping of the Abdomen, From the AJR "How We Do It" Special Series

By exploiting different tissues' characteristic T1 relaxation times, T1-weighted images help distinguish normal and abnormal tissues, aiding assessment of diffuse and local pathologies. However, such images do not provide quantitative T1 values. Advances in abdominal MRI techniques have enabled measurement of abdominal organs' T1 relaxation times, which can be used to create color-coded quantitative maps. T1 mapping is sensitive to tissue microenvironments including inflammation and fibrosis and has received substantial interest for noninvasive imaging of abdominal organ pathology. In particular, quantitative mapping provides a powerful tool for evaluation of diffuse disease by making apparent changes in T1 occurring across organs that may otherwise be difficult to identify. Quantitative measurement also facilitates sensitive monitoring of longitudinal T1 changes. Increased T1 in liver helps to predict parenchymal fibro-inflammation, in pancreas is associated with reduced exocrine function from chronic or autoimmune pancreatitis, and in kidney is associated with impaired renal function and aids diagnosis of chronic kidney disease. In this review, we describe the acquisition, postprocessing, and analysis of T1 maps in the abdomen and explore applications in liver, spleen, pancreas, and kidney. We highlight practical aspects of implementation and standardization, technical pitfalls and confounding factors, and areas of likely greatest clinical impact.

Native hepatic T1-time as a non-invasive predictor of diastolic dysfunction and a monitoring tool for disease progression and treatment response in patients with pulmonary hypertension

AIMS

Hepatic T1-time derived from cardiac magnetic resonance imaging (cMRI) reflects venous congestion and may provide a simple alternative to invasive end-diastolic elastance (Eed) for assessment of right ventricular (RV) diastolic function. We investigated the association of native hepatic T1-time with single-beat Eed and the value of hepatic T1-time for longitudinal monitoring in pulmonary hypertension (PH).

METHODS AND RESULTS

We retrospectively enrolled 85 patients with suspected PH (59% female; 78 with PH diagnosed; 7 with PH excluded) who underwent standard right heart catheterization and cMRI within 24 h between 2015 and 2020. Hepatic T1-time showed moderate to strong correlations (rho >0.3, P ≤ 0.002) with pulmonary vascular resistance, native myocardial T1-time, Eed, RV size and function, brain natriuretic peptide (BNP) level, and 6-min walk distance, and a significant association with functional class (Kruskal-Wallis P < 0.001). Eed, myocardial T1-time, and BNP were independently linked to hepatic T1-time in multivariable regression. Hepatic T1-time > 598 ms predicted elevated Eed with 72.9% sensitivity and 82.1% specificity. Hepatic T1-time was superior to Eed in predicting clinical worsening. In 16 patients with follow-up assessments, those with decreasing hepatic T1-time (7 patients) showed significant hemodynamic improvements, whereas those with increasing hepatic T1-time (9 patients) did not. In a second retrospective cohort of 27 patients with chronic thromboembolic PH undergoing balloon pulmonary angioplasty, hepatic T1-time decreased significantly and hemodynamics improved after the procedure.

CONCLUSIONS

Hepatic T1-time predicts RV diastolic dysfunction and prognosis, and may be useful for monitoring disease progression and treatment response in PH.

Liver T1 Mapping Derived From Cardiac Magnetic Resonance Imaging: A Potential Prognostic Marker in Idiopathic Dilated Cardiomyopathy

BACKGROUND

Hepatic alterations are common aftereffects of heart failure (HF) and ventricular dysfunction. The prognostic value of liver injury markers derived from cardiac MRI studies in nonischemic dilated cardiomyopathy (DCM) patients is unclear.

PURPOSE

Evaluate the prognostic performance of liver injury markers derived from cardiac MRI studies in DCM patients.

STUDY TYPE

Prospective.

POPULATION

Three hundred fifty-six consecutive DCM patients diagnosed according to ESC guidelines (age 48.7 ± 14.2 years, males 72.6%).

FIELD STRENGTH/SEQUENCE

Steady-state free precession, modified Look-Locker inversion recovery T1 mapping and phase sensitive inversion recovery late gadolinium enhancement (LGE) sequences at 3 T.

ASSESSMENT

Clinical characteristics, conventional MRI parameters (ventricular volumes, function, mass), native myocardial and liver T1, liver extracellular volume (ECV), and myocardial LGE presence were assessed. Patients were followed up for a median duration of 48.3 months (interquartile range 42.0-69.9 months). Primary endpoints included HF death, sudden cardiac death, heart transplantation, and HF readmission; secondary endpoints included HF death, sudden cardiac death, and heart transplantation. Models were developed to predict endpoints and the incremental value of including liver parameters assessed.

STATISTICAL TESTS

Optimal cut-off value was determined using receiver operating characteristic curve and Youden method. Survival analysis was performed using Kaplan-Meier and Cox proportional hazard. Discriminative power of models was compared using net reclassification improvement and integrated discriminatory index. P value <0.05 was considered statistically significant.

RESULTS

47.2% patients reached primary endpoints; 25.8% patients reached secondary endpoints. Patients with elevated liver ECV (cut-off 34.4%) had significantly higher risk reaching primary and secondary endpoints. Cox regression showed liver ECV was an independent prognostic predictor, and showed independent prognostic value for primary endpoints and long-term HF readmission compared to conventional clinical and cardiac MRI parameters.

DATA CONCLUSIONS

Liver ECV is an independent prognostic predictor and may serve as an innovative approach for risk stratification for DCM.

EVIDENCE LEVEL

1 TECHNICAL EFFICACY: Stage 2.

Use of Real-Time Cine MRI to Assess the Respirophasic Variation of the Inferior Vena Cava-Proof-of-Concept and Validation Against Transthoracic Echocardiography

BACKGROUND

In clinical practice, the right heart filling status is assessed using the respirophasic variation of the inferior vena cava (IVC) assessed by transthoracic echocardiography (TTE) showing moderate correlations with the catheter-based reference standard.

PURPOSE

To develop and validate a similar approach using MRI.

STUDY TYPE

Prospective.

POPULATION

37 male elite cyclists (mean age 26 ± 4 years).

FIELD STRENGTH/SEQUENCE

Real-time balanced steady-state free-precession cine sequence at 1.5 Tesla.

ASSESSMENT

Respirophasic variation included assessment of expiratory size of the upper hepatic part of the IVC and degree of inspiratory collapse expressed as collapsibility index (CI). The IVC was studied either in long-axis direction (TTE) or using two transverse slices, separated by 30 mm (MRI) during operator-guided deep breathing. For MRI, in addition to the TTE-like diameter, IVC area and major and minor axis diameters were also assessed, together with the corresponding CIs.

STATISTICAL TESTS

Repeated measures ANOVA test with Bonferroni correction. Intraclass correlation coefficient (ICC) and Bland-Altman analysis for intrareader and inter-reader agreement. A P value <0.05 was considered statistically significant.

RESULTS

No significant differences in expiratory IVC diameter were found between TTE and MRI, i.e., 25 ± 4 mm vs. 25 ± 3 mm (P = 0.242), but MRI showed a higher CI, i.e., 76% ± 14% vs. 66% ± 14% (P < 0.05). As the IVC presented a noncircular shape, i.e., major and minor expiratory diameter of 28 ± 4 mm and 21 ± 4 mm, respectively, the CI varied according to the orientation, i.e., 63% ± 27% vs. 75% ± 16%, respectively. Alternatively, expiratory IVC area was 4.3 ± 1.1 cm2 and showed a significantly higher CI, i.e., 86% ± 14% than diameter-based CI (P < 0.05). All participants showed a CI >50% with MRI versus 35/37 (94%) with TTE. ICC values ranged 0.546-0.841 for MRI and 0.545-0.704 for TTE.

CONCLUSION

Assessment of the respirophasic IVC variation is feasible with MRI. Adding this biomarker may be of particular use in evaluating heart failure patients.

LEVEL OF EVIDENCE

1 TECHNICAL EFFICACY STAGE: 2.

VEZF1 loss-of-function mutation underlying familial dilated cardiomyopathy

Dilated cardiomyopathy (DCM), characteristic of left ventricular or biventricular dilation with systolic dysfunction, is the most common form of cardiomyopathy, and a leading cause of heart failure and sudden cardiac death. Aggregating evidence highlights the underlying genetic basis of DCM, and mutations in over 100 genes have been causally linked to DCM. Nevertheless, due to pronounced genetic heterogeneity, the genetic defects underpinning DCM in most cases remain obscure. Hence, this study was sought to identify novel genetic determinants of DCM. In this investigation, whole-exome sequencing and bioinformatics analyses were conducted in a family suffering from DCM, and a novel heterozygous mutation in the VEZF1 gene (coding for a zinc finger-containing transcription factor critical for cardiovascular development and structural remodeling), NM_007146.3: c.490A > T; p.(Lys164*), was identified. The nonsense mutation was validated by Sanger sequencing and segregated with autosome-dominant DCM in the family with complete penetrance. The mutation was neither detected in another cohort of 200 unrelated DCM patients nor observed in 400 unrelated healthy individuals nor retrieved in the Single Nucleotide Polymorphism database, the Human Gene Mutation Database and the Genome Aggregation Database. Biological analyses by utilizing a dual-luciferase reporter assay system revealed that the mutant VEZF1 protein failed to transactivate the promoters of MYH7 and ET1, two genes that have been associated with DCM. The findings indicate VEZF1 as a new gene responsible for DCM, which provides novel insight into the molecular pathogenesis of DCM, implying potential implications for personalized precisive medical management of the patients affected with DCM.

Identification of BMP10 as a Novel Gene Contributing to Dilated Cardiomyopathy

Dilated cardiomyopathy (DCM), characterized by left ventricular or biventricular enlargement with systolic dysfunction, is the most common type of cardiac muscle disease. It is a major cause of congestive heart failure and the most frequent indication for heart transplantation. Aggregating evidence has convincingly demonstrated that DCM has an underlying genetic basis, though the genetic defects responsible for DCM in a larger proportion of cases remain elusive, motivating the ongoing research for new DCM-causative genes. In the current investigation, a multigenerational family affected with autosomal-dominant DCM was recruited from the Chinese Han population. By whole-exome sequencing and Sanger sequencing analyses of the DNAs from the family members, a new BMP10 variation, NM_014482.3:c.166C > T;p.(Gln56*), was discovered and verified to be in co-segregation with the DCM phenotype in the entire family. The heterozygous BMP10 variant was not detected in 268 healthy volunteers enrolled as control subjects. The functional measurement via dual-luciferase reporter assay revealed that Gln56*-mutant BMP10 lost the ability to transactivate its target genes NKX2.5 and TBX20, two genes that had been causally linked to DCM. The findings strongly indicate BMP10 as a new gene contributing to DCM in humans and support BMP10 haploinsufficiency as an alternative pathogenic mechanism underpinning DCM, implying potential implications for the early genetic diagnosis and precision prophylaxis of DCM.

Prognostic Value of Hepatic Native T1 and Extracellular Volume Fraction in Patients with Pulmonary Arterial Hypertension

Background

Right heart failure may lead to impaired liver perfusion and venous congestion, resulting in different extents of liver fibrosis. However, whether hepatic tissue deterioration determined by native T1 mapping and extracellular volume fraction using cardiac magnetic resonance imaging is associated with poor outcomes in patients with pulmonary arterial hypertension remains unclear.

Methods and Results

A total of 131 participants with pulmonary arterial hypertension (mean age, 36±13 years) and 64 healthy controls (mean age, 44±18) between October 2013 and December 2019 were prospectively enrolled. Hepatic native T1 and extracellular volume fraction values were measured using modified Look–Locker inversion recovery T1 mapping sequences. The primary end point was all‐cause mortality; the secondary end point was all‐cause mortality and repeat hospitalization attributable to heart failure. Cox regression models and Kaplan–Meier survival analysis were used to identify the association between variables and clinical outcome. During a median follow‐up of 34.5 months (interquartile range: 25.3–50.8), hepatic native T1 (hazard ratio per 30‐ms increase, 1.22 [95% CI, 1.07–1.39]; P =0.003) and extracellular volume fraction (hazard ratio per 3% increase, 1.18 [95% CI, 1.04–1.34]; P =0.010) values were associated with a higher risk of death. In the multivariate Cox model, hepatic native T1 value (hazard ratio per 30‐ms increase, 1.15 [95% CI, 1.04–1.27]; P =0.009) remained as an independent prognostic factor for the secondary end point.

Conclusions

Hepatic T1 mapping values were predictors of adverse cardiovascular events in participants with pulmonary arterial hypertension and could be novel imaging biomarkers for poor prognosis recognition.

Magnetic resonance relaxometry of the liver - a new imaging biomarker to assess right heart failure in pulmonary hypertension

BACKGROUND

Right heart failure (RHF) in pulmonary hypertension (PH) patients is manifested by increased right atrial (RA) pressure. We hypothesized liver relaxation times measured at cardiovascular magnetic resonance (CMR) can be used to noninvasively assess increased right-sided filling pressure.

METHODS

Forty-five consecutive patients, that is, 37 PH patients and 8 chronic thromboembolic pulmonary disease patients without PH underwent right heart catheterization and CMR. CMR findings were compared to 40 control subjects. Native T1, T2, and extracellular volume (ECV) liver values were measured on the cardiac maps.

RESULTS

Patients with increased RA pressure (i.e.,≥8 mm Hg)(n = 19, RA+ group) showed higher NT-proBNP and CRP values, lower LVEF, MAPSE values, larger atrial size, and higher native T1 and T2 values of the myocardium than patients with normal RA pressure (RA- group, n = 26). Liver T1, T2 and ECV was significantly higher in RA+ than RA- patients and controls, that is, T1: 684 ± 129 ms vs 563 ± 72 ms and 540 ± 34 ms; T2: 60 ± 10 ms vs 49 ± 6 ms and 46 ± 4 ms; ECV: 36 ± 8% vs 29 ± 4% and 30 ± 3%. A positive correlation was found between liver T1, T2 and ECV and RA pressure, that is, r² of 0.61, 0.82, and 0.58, respectively (p < 0.001). ROC analysis to depict increased RA pressure showed an AUC of 0.847, 0.904, 0.816, and 0.645 for liver T1, T2, NT-proNBP and gamma-glutamyl transpeptidase, respectively. Excellent intra- and inter-observer agreement was found for assessment of T1/T2/ECV liver values.

CONCLUSIONS

Assessment of liver relaxation times as part of a comprehensive CMR exam in PH patients may provide valuable information with regard to the presence of passive liver congestion.