Myocardial Native T1 Predicts Load-Independent Left Ventricular Chamber Stiffness In Patients With HFpEF

Cardiovascular Magnetic Resonance Radiomics to Identify Components of the Extracellular Matrix in Dilated Cardiomyopathy

BACKGROUND

Current cardiovascular magnetic resonance sequences cannot discriminate between different myocardial extracellular space (ECSs), including collagen, noncollagen, and inflammation. We sought to investigate whether cardiovascular magnetic resonance radiomics analysis can distinguish between noncollagen and inflammation from collagen in dilated cardiomyopathy.

METHODS

We identified data from 132 patients with dilated cardiomyopathy scheduled for an invasive septal biopsy who underwent cardiovascular magnetic resonance at 3 T. Cardiovascular magnetic resonance imaging protocol included native and postcontrast T1 mapping and late gadolinium enhancement (LGE). Radiomic features were computed from the midseptal myocardium, near the biopsy region, on native T1, extracellular volume (ECV) map, and LGE images. Principal component analysis was used to reduce the number of radiomic features to 5 principal radiomics. Moreover, a correlation analysis was conducted to identify radiomic features exhibiting a strong correlation (r>0.9) with the 5 principal radiomics. Biopsy samples were used to quantify ECS, myocardial fibrosis, and inflammation.

RESULTS

Four histopathological phenotypes were identified: low collagen (n=20), noncollagenous ECS expansion (n=49), mild to moderate collagenous ECS expansion (n=42), and severe collagenous ECS expansion (n=21). Noncollagenous expansion was associated with the highest risk of myocardial inflammation (65%). Although native T1 and ECV provided high diagnostic performance in differentiating severe fibrosis (C statistic, 0.90 and 0.90, respectively), their performance in differentiating between noncollagen and mild to moderate collagenous expansion decreased (C statistic: 0.59 and 0.55, respectively). Integration of ECV principal radiomics provided better discrimination and reclassification between noncollagen and mild to moderate collagen (C statistic, 0.79; net reclassification index, 0.83 [95% CI, 0.45-1.22]; P<0.001). There was a similar trend in the addition of native T1 principal radiomics (C statistic, 0.75; net reclassification index, 0.93 [95% CI, 0.56-1.29]; P<0.001) and LGE principal radiomics (C statistic, 0.74; net reclassification index, 0.59 [95% CI, 0.19-0.98]; P=0.004). Five radiomic features per sequence were identified with correlation analysis. They showed a similar improvement in performance for differentiating between noncollagen and mild to moderate collagen (native T1, ECV, LGE C statistic, 0.75, 0.77, and 0.71, respectively). These improvements remained significant when confined to a single radiomic feature (native T1, ECV, LGE C statistic, 0.71, 0.70, and 0.64, respectively).

CONCLUSIONS

Radiomic features extracted from native T1, ECV, and LGE provide incremental information that improves our capability to discriminate noncollagenous expansion from mild to moderate collagen and could be useful for detecting subtle chronic inflammation in patients with dilated cardiomyopathy.

Sudden Cardiac Death Risk Stratification in Heart Failure With Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) poses a significant clinical challenge, with sudden cardiac death (SCD) emerging as one of the leading causes of mortality. Despite advancements in cardiovascular medicine, predicting and preventing SCD in HFpEF remains complex due to multifactorial pathophysiological mechanisms and patient heterogeneity. Unlike heart failure with reduced ejection fraction, where impaired contractility and ventricular remodeling predominate, HFpEF pathophysiology involves heavy burden of comorbidities such as hypertension, obesity, and diabetes. Diverse mechanisms, including diastolic dysfunction, microvascular abnormalities, and inflammation, also contribute to distinct disease and SCD risk profiles. Various parameters such as clinical factors and electrocardiogram features have been proposed in SCD risk assessment. Advanced imaging modalities and biomarkers offer promise in risk prediction, yet comprehensive risk stratification models specific to HFpEF ar0e lacking. This review offers recent evidence on SCD risk factors and discusses current therapeutic strategies aimed at reducing SCD risk in HFpEF.

A comparison of myocardial magnetic resonance extracellular volume mapping at 3 T against histology of tissue collagen in severe aortic valve stenosis and obstructive hypertrophic cardiomyopathy

OBJECTIVE

Quantitative extracellular volume fraction (ECV) mapping with MRI is commonly used to investigate in vivo diffuse myocardial fibrosis. This study aimed to validate ECV measurements against ex vivo histology of myocardial tissue samples from patients with aortic valve stenosis or hypertrophic cardiomyopathy.

MATERIALS AND METHODS

Sixteen patients underwent MRI examination at 3 T to acquire native T1 maps and post-contrast T1 maps after gadobutrol administration, from which hematocrit-corrected ECV maps were estimated. Intra-operatively obtained myocardial tissue samples from the same patients were stained with picrosirius red for quantitative histology of myocardial interstitial fibrosis. Correlations between in vivo ECV and ex vivo myocardial collagen content were evaluated with regression analyses.

RESULTS

Septal ECV was 30.3% ± 4.6% and correlated strongly (n = 16, r = 0.70; p = 0.003) with myocardial collagen content. Myocardial native T1 values (1206 ± 36 ms) did not correlate with septal ECV (r = 0.41; p = 0.111) or with myocardial collagen content (r = 0.32; p = 0.227).

DISCUSSION

We compared myocardial ECV mapping at 3 T against ex vivo histology of myocardial collagen content, adding evidence to the notion that ECV mapping is a surrogate marker for in vivo diffuse myocardial fibrosis.

Relationship Between Results of Pathological Evaluation of Endomyocardial Biopsy and Echocardiographic Indices in Patients With Non-Ischemic Cardiomyopathy

Background: Endomyocardial biopsy (EMB) is a useful modality in diagnosing the origin of cardiomyopathy and the condition of the impaired myocardium. However, the usefulness of obtaining an EMB from the right and left ventricles (RV and LV, respectively), and its associations with echocardiographic parameters, have not been explored. Methods and Results: Ninety-five consecutive patients with non-ischemic cardiomyopathy excluding myocarditis who underwent EMB between July 2017 and May 2019 were studied. Seventy-nine RV and 93 LV biopsy specimens were pathologically analyzed. The relationships among echocardiographic data before EMB and pathologically measured cardiomyocyte diameter (CMD) and interstitial fibrosis (IF) were evaluated. CMD in both LV and RV specimens correlated with echocardiographic LV morphology, but only CMD in the LV was significantly correlated with cardiac function evaluation, including LV ejection fraction, E' and E/E'. In contrast, there were no significant correlations between IF in either the LV or RV and any echocardiographic parameters measured. Furthermore, CMD of both ventricles was significantly correlated with B-type natriuretic peptide (BNP) concentration at EMB, whereas IF of the LV was barely related and IF of the RV was not significantly correlated with BNP concentrations. Conclusions: Pathologically evaluated CMD of EMB specimens of the LV may be more related to functional parameters for heart failure status and LV geometry on echocardiographic examination, than IF.

The role of cardiac magnetic resonance imaging in the assessment of heart failure with preserved ejection fraction

Heart failure (HF) is a major cause of morbidity and mortality worldwide. Current classifications of HF categorize patients with a left ventricular ejection fraction of 50% or greater as HF with preserved ejection fraction or HFpEF. Echocardiography is the first line imaging modality in assessing diastolic function given its practicality, low cost and the utilization of Doppler imaging. However, the last decade has seen cardiac magnetic resonance (CMR) emerge as a valuable test for the sometimes challenging diagnosis of HFpEF. The unique ability of CMR for myocardial tissue characterization coupled with high resolution imaging provides additional information to echocardiography that may help in phenotyping HFpEF and provide prognostication for patients with HF. The precision and accuracy of CMR underlies its use in clinical trials for the assessment of novel and repurposed drugs in HFpEF. Importantly, CMR has powerful diagnostic utility in differentiating acquired and inherited heart muscle diseases presenting as HFpEF such as Fabry disease and amyloidosis with specific treatment options to reverse or halt disease progression. This state of the art review will outline established CMR techniques such as transmitral velocities and strain imaging of the left ventricle and left atrium in assessing diastolic function and their clinical application to HFpEF. Furthermore, it will include a discussion on novel methods and future developments such as stress CMR and MR spectroscopy to assess myocardial energetics, which show promise in unraveling the mechanisms behind HFpEF that may provide targets for much needed therapeutic interventions.

Advances in Multimodality Cardiovascular Imaging in the Diagnosis of Heart Failure With Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) is a syndrome defined by the presence of heart failure symptoms and increased levels of circulating natriuretic peptide (NP) in patients with preserved left ventricular ejection fraction and various degrees of diastolic dysfunction (DD). HFpEF is a complex condition that encompasses a wide range of different etiologies. Cardiovascular imaging plays a pivotal role in diagnosing HFpEF, in identifying specific underlying etiologies, in prognostic stratification, and in therapeutic individualization. Echocardiography is the first line imaging modality with its wide availability; it has high spatial and temporal resolution and can reliably assess systolic and diastolic function. Cardiovascular magnetic resonance (CMR) is the gold standard for cardiac morphology and function assessment, and has superior contrast resolution to look in depth into tissue changes and help to identify specific HFpEF etiologies. Differently, the most important role of nuclear imaging [i.e., planar scintigraphy and/or single photon emission CT (SPECT)] consists in the screening and diagnosis of cardiac transthyretin amyloidosis (ATTR) in patients with HFpEF. Cardiac CT can accurately evaluate coronary artery disease both from an anatomical and functional point of view, but tissue characterization methods have also been developed. The aim of this review is to critically summarize the current uses and future perspectives of echocardiography, nuclear imaging, CT, and CMR in patients with HFpEF.

Myocardial tissue imaging with cardiovascular magnetic resonance

Alteration in myocardial tissue, such as myocardial fibrosis, edema, inflammation, or accumulation with amyloid, lipids, or iron, has an important role in the cardiac remodeling that leads to diastolic and/or systolic dysfunction and the development of chronic heart failure, increasing the risk of adverse cardiovascular events. Thus, the early detection of changes at myocardial tissue level has great diagnostic and prognostic potential. The gold standard technique to assess these myocardial alterations is endomyocardial biopsy. However, this has been limited to a few patients due to the invasive nature, sampling errors, and its inability to assess the entire myocardium. Cardiovascular magnetic resonance (CMR) has emerged as the gold standard imaging not only for assessing cardiac volume, function quantification, and viability but also for noninvasive myocardial tissue characterization over the past decade. Its ability to characterize myocardial tissue composition is unique among noninvasive imaging modalities in cardiovascular disease. Currently, multi-parametric myocardial characterization with T1, T2, and extracellular volume has the potential to identify and track diffuse pathology in various diseases. In this review article, we present the role of established and emerging CMR techniques in myocardial tissue characterization, with an emphasis on T1 and T2 mapping, in clinical practice.

A Radiomic MRI based Nomogram for Prediction of Heart Failure with Preserved Ejection Fraction in Systemic Lupus Erythematosus Patients: Insights From a Three-Center Prospective Study

BACKGROUND

Myocardial T1 and extracellular volume (ECV) fraction values have important roles in the prognostication of heart failure with preserved ejection fraction (HFpEF). However, the traditional mean quantification of intensity levels is not sufficient.

PURPOSE

To evaluate a T1 map-based radiomic nomogram as a long-term prognosticator for HFpEF in systemic lupus erythematosus (SLE) patients.

STUDY TYPE

Prospective.

POPULATION

A total of 115 SLE patients and 50 age- and gender-matched controls.

FIELD STRENGTH/SEQUENCE

A 3.0 T scanner; cine imaging, precontrast and post-contrast T1 mapping and T2 mapping sequences.

ASSESSMENT

A radiomic nomogram was developed based on precontrast T1 mapping. Three independent readers assessed and compared the ECV value and the value of the radiomic nomogram for predicting HFpEF in SLE patients.

STATISTICAL TEST

Cox proportional hazard models, Youden index for determining cut-off values for high HFpEF risk vs. low HFpEF risk classification, Kaplan-Meier analysis, intraclass correlation (ICC), and Uno C statistic test.

RESULTS

During a median follow-up of 27 (interquartile range, 19-37) months, 31 SLE patients developed HFpEF. Patients with elevated ECV (≥31%) and a higher output (≥42.7) from the radiomic feature "S_33_sum average" of the precontrast T1 map had a significantly higher risk of developing HFpEF than those who had lower ECV (<31%) and an output <42.7. Patients with a higher "S_33_sum average" value on precontrast T1 map had a significantly increased risk for HFpEF (hazard ratio, 1.363, 95% CI, 1.130-1.645), after adjusting for covariates including ECV and LVEF. Finally, "S_33_sum average" from precontrast T1 mapping had modest but significantly incremental prognostic value over the mean ECV value (Uno C statistic comparing models, 0.860 vs. 0.835).

DATA CONCLUSION

The precontrast T1 map-based radiomic nomogram, as a measure of diffuse myocardial fibrosis was associated with HFpEF and provided modest prognostic value for predicting HFpEF in SLE patients.

EVIDENCE LEVEL

1 TECHNICAL EFFICACY: Stage 2.

Comparison of haemodynamic response to muscle reflex in heart failure with reduced vs. preserved ejection fraction

Aims

Isometric handgrip (IHG) training reduces the blood pressure in patients with hypertension. It is unclear how IHG exercise affects the haemodynamics and cardiovascular function through the muscle reflex in patients with heart failure (HF) with reduced (HFrEF) and preserved ejection fraction (HFpEF).

Methods and results

Twenty patients (HFrEF: n = 10, HFpEF: n = 10) underwent left ventricular (LV) pressure–volume assessments using a conductance catheter and microtip manometer to evaluate haemodynamics, LV and arterial function, and LV‐arterial coupling during 3 min of IHG at 30% of maximal voluntary contraction (MVC), followed by 3 min of post‐exercise circulatory arrest (PECA). Three minutes of IHG exercise produced significant and modest increases in the heart rate (HR) and LV end‐systolic pressure (LVESP), respectively, in both HFpEF and HFrEF groups. In HFrEF, the increase in LVESP was caused by the variable increase in effective arterial elastance (Ea), which was counterbalanced by the increase in LV end‐systolic elastance (Ees), resulting in a maintained Ees/Ea. In HFpEF, the increase in LVESP was not accompanied by changes in Ea, Ees, Ees/Ea, or LV end‐diastolic pressure. LVESP during PECA was not maintained in HFpEF, suggesting smaller metabo‐reflex activity in HFpEF.

Conclusions

The IHG exercise used in this study may increase the LVESP and LVEDP without detrimental effects on cardiac function or ventricular‐arterial coupling, especially in HFpEF patients. The effects of IHG exercise on haemodynamics and ventricular‐arterial coupling may be affected by the patient background and the type and intensity of the exercise.

Myocardial Tissue Characterization in Heart Failure with Preserved Ejection Fraction: From Histopathology and Cardiac Magnetic Resonance Findings to Therapeutic Targets

Heart failure with preserved ejection fraction (HFpEF) is a complex clinical syndrome responsible for high mortality and morbidity rates. It has an ever growing social and economic impact and a deeper knowledge of molecular and pathophysiological basis is essential for the ideal management of HFpEF patients. The association between HFpEF and traditional cardiovascular risk factors is known. However, myocardial alterations, as well as pathophysiological mechanisms involved are not completely defined. Under the definition of HFpEF there is a wide spectrum of different myocardial structural alterations. Myocardial hypertrophy and fibrosis, coronary microvascular dysfunction, oxidative stress and inflammation are only some of the main pathological detectable processes. Furthermore, there is a lack of effective pharmacological targets to improve HFpEF patients' outcomes and risk factors control is the primary and unique approach to treat those patients. Myocardial tissue characterization, through invasive and non-invasive techniques, such as endomyocardial biopsy and cardiac magnetic resonance respectively, may represent the starting point to understand the genetic, molecular and pathophysiological mechanisms underlying this complex syndrome. The correlation between histopathological findings and imaging aspects may be the future challenge for the earlier and large-scale HFpEF diagnosis, in order to plan a specific and effective treatment able to modify the disease's natural course.

Multiple-Tissue and Multilevel Analysis on Differentially Expressed Genes and Differentially Correlated Gene Pairs for HFpEF

Heart failure with preserved ejection fraction (HFpEF) is a complex disease characterized by dysfunctions in the heart, adipose tissue, and cerebral arteries. The elucidation of the interactions between these three tissues in HFpEF will improve our understanding of the mechanism of HFpEF. In this study, we propose a multilevel comparative framework based on differentially expressed genes (DEGs) and differentially correlated gene pairs (DCGs) to investigate the shared and unique pathological features among the three tissues in HFpEF. At the network level, functional enrichment analysis revealed that the networks of the heart, adipose tissue, and cerebral arteries were enriched in the cell cycle and immune response. The networks of the heart and adipose tissues were enriched in hemostasis, G-protein coupled receptor (GPCR) ligand, and cancer-related pathway. The heart-specific networks were enriched in the inflammatory response and cardiac hypertrophy, while the adipose-tissue-specific networks were enriched in the response to peptides and regulation of cell adhesion. The cerebral-artery-specific networks were enriched in gene expression (transcription). At the module and gene levels, 5 housekeeping DEGs, 2 housekeeping DCGs, 6 modules of merged protein–protein interaction network, 5 tissue-specific hub genes, and 20 shared hub genes were identified through comparative analysis of tissue pairs. Furthermore, the therapeutic drugs for HFpEF-targeting these genes were examined using molecular docking. The combination of multitissue and multilevel comparative frameworks is a potential strategy for the discovery of effective therapy and personalized medicine for HFpEF.

Trajectory of left ventricular geometry and diastolic dysfunction in hereditary transthyretin cardiac amyloidosis

Amyloid transthyretin (ATTR) depositions cause left ventricular (LV) hypertrophy, diastolic dysfunction, and heart failure. The time course of changes in LV geometry and diastolic dysfunction has not been fully reported in patients with ATTR cardiomyopathy. A 79‐year‐old woman with previous myocardial infraction presented with shortness of breath on exertion, and progressive bilateral lower extremity weakness and polyneuropathy. She was diagnosed with Val30Met hereditary ATTR cardiomyopathy by cardiac biopsy and genetic testing. During the past 5 year period, significant LV concentric remodelling with small LV cavity occurred, resulting in an increased LV stiffness and prolonged LV relaxation. This case report highlights the time course of changes in LV geometry and diastolic function and the importance of early diagnosis of ATTR cardiomyopathy.