The Prognostic Role of Tissue Characterisation using Cardiovascular Magnetic Resonance in Heart Failure

Chronic troponin elevation assessed by myocardial T1 mapping in patients with stable coronary artery disease

BACKGROUND

Cardiac troponin detected with sensitive assays can be chronically elevated, in the absence of unstable coronary syndromes. In patients with chronic coronary artery disease, clinically silent ischemic episodes may cause chronic troponin release. T1 mapping is a cardiovascular magnetic resonance technique useful in quantitative cardiac tissue characterization. We selected patients with anatomically and functionally normal hearts to investigate associations between chronic troponin release and myocardial tissue characteristics assessed by T1 mapping.

METHODS

We investigated the relationship between cardiac troponin I concentrations and cardiovascular magnetic resonance T1 mapping parameters in patients with stable coronary artery disease enrolled in MASS V study before elective revascularization. Participants had no previous myocardial infarction, negative late gadolinium enhancement, normal left ventricular function, chamber dimensions and wall thickness.

RESULTS

A total of 56 patients were analyzed in troponin tertiles: nativeT1 and extracellular volume (ECV) values (expressed as means ± standard deviations) increased across tertiles: nativeT1 (1006 ± 27 ms vs 1016 ± 27 ms vs 1034 ± 37 ms, ptrend = 0.006) and ECV (22 ± 3% vs 23 ± 1.9% vs 25 ± 3%, ptrend = 0.007). Cardiac troponin I concentrations correlated with native T1(R = 0.33, P = .012) and ECV (R = 0.3, P = .025), and were independently associated with nativeT1 (P = .049) and ventricular mass index (P = .041) in multivariable analysis.

CONCLUSION

In patients with chronic coronary artery disease and structurally normal hearts, troponin I concentrations correlated with T1 mapping parameters, suggesting that diffuse edema or fibrosis scattered in normal myocardium might be associated with chronic troponin release.

The Relationship between Extracellular Volume Compartments and Matrix Metalloproteinases-2 in Left Ventricular Remodeling after Myocardial Infarction

BACKGROUND

Matrix metalloproteinases (MMPs) can affect myocardial extracellular volume (ECV) and its compartments, and this can provide more detailed information about the mechanism of adverse left ventricular (LV) remodeling (AR) after acute myocardial infarction (MI).

OBJECTIVES

To investigate the role of changes (Δ) in ECV compartments (matrix volume (MVi) and cell volume (CVi)) in the development of AR after MI, and their relationship with MMP-2 expressions.

METHODS

Ninety-two first MI patients who underwent 3 Tesla cardiovascular magnetic resonance imaging performed 2 weeks (baseline) and 6 months post-MI. We measured T1 mapping with MOLLI sequences. ECV was performed post-gadolinium enhancement. ECV and LV mass were used to calculate MVi and CVi. AR was defined as an increase of ≥ 12% in LV end-diastolic volume in 6 months. MMPs were measured using a bead-based multiplex immunoassay system at first day (baseline) and 2 weeks post-MI. P <0.05 was accepted as statistically significant.

RESULTS

Mean ECV and mean MVi baseline levels were higher in AR group compared to without AR group (42.9±6.4 vs 39.3±8.2%, p= 0.037; 65.2±13.7 vs 56.7±14.7 mL/m2, p=0.010; respectively). CVi levels was similar between groups. A positive correlation was found between baseline levels of MMP-2 and baseline levels of ECV (r=0.535, p<0.001) and MVi (r=0.549, p<0.001). Increased ΔMVi levels was independently predictor of AR (OR=1.03, p=0.010). ΔMVi had superior diagnostic performance compared to ΔECV in predicting AR (ΔAUC: 0.215±0.07, p<0.001).

CONCLUSION

High MVi levels are associated with AR, and ΔMVi was independently predictor of AR. This may be associated with MMP-2 release due to increased inflammatory response.

Abnormalities in Cardiac Structure and Function among Individuals with CKD: The COMBINE Trial

Background

Individuals with CKD have a high burden of cardiovascular disease (CVD). Abnormalities in cardiac structure and function represent subclinical CVD and can be assessed by cardiac magnetic resonance imaging (cMRI).

Methods

We investigated differences in cMRI parameters in 140 individuals with CKD stages 3b-4 who participated in the CKD Optimal Management with BInders and NicotinamidE (COMBINE) trial and in 24 age- and sex-matched healthy volunteers. Among COMBINE participants, we examined the associations of eGFR, urine albumin-creatinine ratio (UACR), phosphate, fibroblast growth factor 23 (FGF23), and parathyroid hormone (PTH) with baseline (N=140) and 12-month change (N=112) in cMRI parameters.

Results

Mean (SD) ages of the COMBINE participants and healthy volunteers were 64.9 (11.9) and 60.4 (7.3) years, respectively. The mean (SD) baseline eGFR values in COMBINE participants were 32.1 (8.0) and 85.9 (16.0) ml/min per 1.73 m² in healthy volunteers. The median (interquartile range [IQR]) UACR in COMBINE participants was 154 (20.3-540.0) mg/g. Individuals with CKD had lower mitral valve E/A ratio compared with healthy volunteers (for CKD versus non-CKD, β estimate, -0.13; 95% CI, -0.24 to -0.012). Among COMBINE participants, multivariable linear regression analyses showed that higher UACR was significantly associated with lower mitral valve E/A ratio (β estimate per 1 unit increase in natural-log UACR, -0.06; 95% CI, -0.09 to -0.03). This finding was preserved among individuals without baseline CVD. UACR was not associated with 12-month change in any cMRI parameter. eGFR, phosphate, FGF23, and PTH were not associated with any cMRI parameter in cross-sectional or change analyses.

Conclusions

Individuals with CKD stages 3b-4 have evidence of cMRI abnormalities. Albuminuria was independently associated with diastolic dysfunction, as assessed by mitral valve E/A ratio, in individuals with CKD with and without clinical CVD. Albuminuria was not associated with change in any cMRI parameter.

Cardiovascular Magnetic Resonance Imaging and Heart Failure

Purpose of Review

The purpose of this review is to summarize the application of cardiac magnetic resonance (CMR) in the diagnostic and prognostic evaluation of patients with heart failure (HF).

Recent Findings

CMR is an important non-invasive imaging modality in the assessment of ventricular volumes and function and in the analysis of myocardial tissue characteristics. The information derived from CMR provides a comprehensive evaluation of HF. Its unique ability of tissue characterization not only helps to reveal the underlying etiologies of HF but also offers incremental prognostic information.

Summary

CMR is a useful non-invasive tool for the diagnosis and assessment of prognosis in patients suffering from heart failure.

Ischemic and non-ischemic patterns of late gadolinium enhancement in heart failure with reduced ejection fraction

BACKGROUND

Late gadolinium enhancement (LGE) by cardiac magnetic resonance (CMR) may reveal myocardial fibrosis which is associated with adverse clinical outcomes in patients undergoing implantable cardioverter-defibrillator (ICD) placement. At the same time, transmural LGE in the posterolateral wall is related to nonresponse to conventional cardiac resynchronization therapy (CRT). Herein, the aim was to assess the presence and determinants of LGE in CMR in heart failure (HF) with reduced ejection fraction.

METHODS

Sixty-seven patients were included (17.9% female, aged 45 [29-60] years), who underwent LGE-CMR and had left ventricular ejection fraction (LVEF) as determined by echocardiography.

RESULTS

In HF patients with LVEF ≤ 35% (n = 29), ischemic and non-ischemic patterns of LGE were observed in 51.7% and 34.5% of patients, respectively. In controls (n = 38), these patterns were noted in 23.7% and 42.1% of patients, respectively. HF patients with LVEF ≤ 35% and transmural LGE in the posterolateral wall (31.0%) were characterized by older age, coronary artery disease (CAD) and previous myocardial infarction (MI) (61 ± 6 vs. 49 ± 16 years, p = 0.008, 100% vs. 40%, p = 0.003 and 78% vs. 25%, p = 0.014, respectively). In patients with LVEF ≤ 35%, LGE of any type, diagnosed in 86.2% of patients, was associated with CAD (68% vs. 0%, p = 0.02), while only trends were observed for its association with older age and previous MI (p = 0.08 and p = 0.12, respectively).

CONCLUSIONS

Among HF patients with LVEF ≤ 35%, clinical factors including older age, CAD, and previous MI are associated with transmural LGE in the posterolateral wall, while CAD is associated with LGE. This data may have potential implications for planning ICD and CRT placement procedures.

Clinical application and technical considerations of T1 & T2(*) mapping in cardiac, liver, and renal imaging

Pathological tissue alterations due to disease processes such as fibrosis, edema and infiltrative disease can be non-invasively visualized and quantified by MRI using T₁ and T₂ relaxation properties. Pixel-wise mapping of T₁ and T₂ image sequences enable direct quantification of T₁, T₂(*), and extracellular volume values of the target organ of interest. Tissue characterization based on T₁ and T₂(*) mapping is currently making the transition from a research tool to a clinical modality, as clinical usefulness has been established for several diseases such as myocarditis, amyloidosis, Anderson-Fabry and iron deposition. Other potential clinical applications besides the heart include, quantification of steatosis, cirrhosis, hepatic siderosis and renal fibrosis. Here, we provide an overview of potential clinical applications of T₁ andT₂(*) mapping for imaging of cardiac, liver and renal disease. Furthermore, we give an overview of important technical considerations necessary for clinical implementation of quantitative parametric imaging, involving data acquisition, data analysis, quality assessment, and interpretation. In order to achieve clinical implementation of these techniques, standardization of T₁ and T₂(*) mapping methodology and validation of impact on clinical decision making is needed.