Late gadolinium enhancement confined to the right ventricular insertion points in hypertrophic cardiomyopathy: an intermediate stage phenotype?

The Role of Multimodality Imaging in Cardiomyopathy

PURPOSE OF REVIEW

There has been increasing use of multimodality imaging in the evaluation of cardiomyopathies.

RECENT FINDINGS

Echocardiography, cardiac magnetic resonance (CMR), cardiac nuclear imaging, and cardiac computed tomography (CCT) play an important role in the diagnosis, risk stratification, and management of patients with cardiomyopathies. Echocardiography is essential in the initial assessment of suspected cardiomyopathy, but a multimodality approach can improve diagnostics and management. CMR allows for accurate measurement of volumes and function, and can easily detect unique pathologic structures. In addition, contrast imaging and parametric mapping enable the characterization of tissue features such as scar, edema, infiltration, and deposition. In non-ischemic cardiomyopathies, metabolic and molecular nuclear imaging is used to diagnose rare but life-threatening conditions such amyloidosis and sarcoidosis. There is an expanding use of CCT for planning electrophysiology procedures such as cardioversion, ablations, and device placement. Furthermore, CCT can evaluate for complications associated with advanced heart failure therapies such as cardiac transplant and mechanical support devices. Innovations in multimodality cardiac imaging should lead to increased volumes and better outcomes.

Subendocardial Involvement as an Underrecognized LGE Subtype Related to Adverse Outcomes in Hypertrophic Cardiomyopathy

BACKGROUND

Late gadolinium enhancement (LGE) has been established as an independent predictor for adverse outcomes in hypertrophic cardiomyopathy (HCM). However, the prevalence and clinical significance of some LGE subtypes have not been well demonstrated.

OBJECTIVES

In this study, the authors sought to investigate the prognostic value of subendocardium-involved LGE pattern and location of right ventricle insertion points (RVIPs) with LGE in HCM patients.

METHODS

In this single-center retrospective study, 497 consecutive HCM patients with LGE confirmed by cardiac magnetic resonance (CMR) were included. Subendocardium-involved LGE was defined as LGE involving subendocardium not corresponding to a coronary vascular distribution. Subjects with ischemic heart disease that would contribute to subendocardial LGE were excluded. Endpoints included a composite of heart failure-related events, arrhythmic events, and stroke.

RESULTS

Of the 497 patients, subendocardium-involved LGE and RVIP LGE were observed in 184 (37.0%) and 414 (83.3%), respectively. Extensive LGE (≥15% of left ventricular mass) was detected in 135 patients. During a median follow-up of 57.9 months, 66 patients (13.3%) experienced composite endpoints. Patients with extensive LGE had a significantly higher annual incidence of adverse events (5.1% vs 1.9% per year; P < 0.001). However, spline analysis showed that the association between LGE extent and HRs for adverse outcomes tended to be nonlinear. The risk of composite endpoint increased with percentage increase in LGE extent in patients with extensive LGE, whereas a similar trend was not observed in patients with nonextensive LGE (<15%). In patients with extensive LGE, LGE extent significantly correlated with composite endpoints (HR: 1.05; P = 0.03) after adjusting for left ventricular ejection fraction <50%, atrial fibrillation, and nonsustained ventricular tachycardia, whereas in patients with nonextensive LGE, subendocardium-involved LGE rather than LGE extent was independently associated with adverse outcomes (HR: 2.12; P = 0.03). RVIP LGE was not significantly associated with poor outcomes.

CONCLUSIONS

In HCM patients with nonextensive LGE, the presence of subendocardium-involved LGE rather than LGE extent is associated with unfavorable outcomes. Given that the prognostic value of extensive LGE has been broadly recognized, subendocardial involvement as an underrecognized LGE pattern shows the potential to improve risk stratification in HCM patients with nonextensive LGE.

Approach to optimal assessment of right ventricular remodelling in heart transplant recipients: insights from myocardial work index, T1 mapping, and endomyocardial biopsy

AIMS

Right ventricular (RV) dysfunction is an important cause of graft failure after heart transplantation (HTx). We sought to investigate relative merits of echocardiographic tools and cardiac magnetic resonance (CMR) with T1 mapping for the assessment of functional adaptation and remodelling of the RV in HTx recipients.

METHODS AND RESULTS

Sixty-one complete data set of echocardiography, CMR, right heart catheterization, and biopsy were obtained. Myocardial work index (MWI) was quantified by integrating longitudinal strain (LS) with invasively measured pulmonary artery pressure. CMR derived RV volumes, T1 time, and extracellular volume (ECV) were quantified. Endomyocardial biopsy findings were used as the reference standard for myocardial microstructural changes. In HTx recipients who never had a previous allograft rejection, longitudinal function parameters were lower than healthy organ donors, while ejection fraction (EF) (52.0 ± 8.7%) and MWI (403.2 ± 77.2 mmHg%) were preserved. Rejection was characterized by significantly reduced LS, MWI, longer T1 time, and increased ECV that improved after recovery, whereas RV volumes and EF did not change MWI was the strongest determinant of rejection related myocardial damage (area under curve: 0.812, P < 0.0001, 95% CI: 0.69-0.94) with good specificity (77%), albeit modest sensitivity. In contrast, T1 time and ECV were sensitive (84%, both) but not specific to detect subclinical RV damage.

CONCLUSION

Subclinical adaptive RV remodelling is characterized by preserved RV EF despite longitudinal function abnormalities, except for MWI. While ultrastructural damage is reflected by MWI, ECV, and T1 time, only MWI has the capability to discriminate functional adaptation from transition to subclinical structural damage.

Major Clinical Issues in Hypertrophic Cardiomyopathy

By actively implementing contemporary management strategies in hypertrophic cardiomyopathy, morbidity and mortality can be substantially reduced. In this review, we discuss the pathophysiology and management of the major clinical issues in hypertrophic cardiomyopathy, including sudden cardiac death, atrial fibrillation and thromboembolism, dynamic left ventricular outflow tract obstruction, and heart failure progression. Although echocardiography and cardiac magnetic resonance imaging currently play an essential and complementary role in the management of hypertrophic cardiomyopathy, further studies are needed to establish how developing techniques such as myocardial deformation and late gadolinium enhancement can provide better risk stratification and guide treatment.

Hypertrophic cardiomyopathy (HCM) is one of the most common inheritable cardiomyopathies. Contemporary management strategies, including the advent of implantable cardioverter-defibrillators and effective anticoagulation, have substantially improved the clinical course of HCM patients; however, the disease burden of HCM is still high in Korea. Sudden cardiac death (SCD), atrial fibrillation and thromboembolic risk, dynamic left ventricular outflow tract (LVOT) obstruction, and heart failure (HF) progression remain important issues in HCM. SCD in HCM can be effectively prevented with implantable cardioverter-defibrillators. However, appropriate patient selection is important for primary prevention, and the 5-year SCD risk score and the presence of major SCD risk factors should be considered. Anticoagulation should be initiated in all HCM patients with atrial fibrillation regardless of the CHA₂DS₂-VASc score, and non-vitamin K antagonist oral anticoagulants are the first option. Symptomatic dynamic LVOT obstruction is first treated medically with negative inotropes, and if symptoms persist, septal reduction therapy is considered. The recently approved myosin inhibitor mavacamten is promising. HF in HCM is usually related to diastolic dysfunction, while about 5% of HCM patients show reduced left ventricular ejection fraction <50%, also referred to as “end-stage” HCM. Myocardial fibrosis plays an important role in the progression to advanced HF in patients with HCM. Patients who do not respond to guideline-directed medical therapy can be considered for heart transplantation. The development of imaging techniques, such as myocardial deformation on echocardiography and late gadolinium enhancement on cardiac magnetic resonance, can provide better risk evaluation and decision-making for management strategies in HCM.

Myocardial Injury and Fibrosis From Acute Carbon Monoxide Poisoning: A Prospective Observational Study

OBJECTIVES

This study sought to evaluate the prevalence and patterns of late gadolinium enhancement (LGE) after carbon monoxide (CO) poisoning using cardiac magnetic resonance (CMR) imaging (CMRI) and transthoracic echocardiography (TTE).

BACKGROUND

In acute CO poisoning, cardiac injury can predict mortality. However, it remains unclear why increased mortality and cardiovascular events occur despite normalization of CO-induced elevated troponin I (TnI) and cardiac dysfunction.

METHODS

Patients with acute CO poisoning with elevated TnI were evaluated. CMRI was performed within 7 days of CO exposure and after 4 to 5 months. Patients were divided into LGE (n = 72; 69.2%) and no-LGE (n = 32; 30.8%) groups.

RESULTS

In the LGE group, 39.4%, 4.8%, and 25.0% of patients exhibited midwall, subendocardial, and right ventricular insertion point injury, respectively. Diffuse injury was observed in 22.1% of patients, and 67.6% of the 37 patients who underwent follow-up CMRI showed no interval change. On TTE, baseline left ventricular ejection fraction and global longitudinal strain were significantly deteriorated in the LGE group; serial TTE within 7 days indicated that only left ventricular global longitudinal strain remained significantly deteriorated. Three cases of mortality occurred in the LGE group during the 1-year follow-up.

CONCLUSIONS

The LGE prevalence in patients with acute CO poisoning with elevated TnI levels, with no underlying cardiovascular diseases and eligible for CMRI, was 69.2%; this proportion primarily comprised patients with a midwall injury. Of the 37 patients who underwent follow-up CMRI, most chronic phase images showed no interval change. Myocardial fibrosis detected on CMR images was related to acute myocardial dysfunction and subacute deterioration of myocardial strain on TTE. (Cardiac Magnetic Resonance Image in Acute Carbon Monoxide Poisoning; NCT04419298).

Associations of inflammatory markers with impaired left ventricular diastolic and systolic function in collagen-induced arthritis

Background

High-grade inflammation may play a pivotal role in the pathogenesis of left ventricular (LV) dysfunction. Evidence to support a role of systemic inflammation in mediating impaired LV function in experimental models of rheumatoid arthritis (RA) remains limited. The aim of the present study was to determine the effects of high-grade systemic inflammation on LV diastolic and systolic function in collagen-induced arthritis (CIA).

Methods

To induce CIA, bovine type-II collagen emulsified in incomplete Freund’s adjuvant was injected at the base of the tail into 21 three-month old Sprague Dawley rats. Nine-weeks after the first immunisation, LV function was assessed by pulsed Doppler, tissue Doppler imaging and Speckle tracking echocardiography. Cardiac collagen content was determined by picrosirius red staining; circulating inflammatory markers were measured using ELISA.

Results

Compared to controls (n = 12), CIA rats had reduced myocardial relaxation as indexed by lateral e’ (early diastolic mitral annular velocity) and e’/a’ (early-to-late diastolic mitral annular velocity) and increased filling pressures as indexed by E/e’. No differences in ejection fraction and LV endocardial fractional shortening between the groups were recorded. LV global radial and circumferential strain and strain rate were reduced in CIA rats compared to controls. Higher concentrations of circulating inflammatory markers were associated with reduced lateral e’, e’/a’, radial and circumferential strain and strain rate. Greater collagen content was associated with increased concentrations of circulating inflammatory markers and E/e’.

Conclusion

High-grade inflammation is associated with impaired LV diastolic function and greater myocardial deformation independent of haemodynamic load in CIA rats.

Potential Value of Native T1 Mapping in Symptomatic Adults with Congenital Heart Disease: A Preliminary Study of 3.0 Tesla Cardiac Magnetic Resonance Imaging

The native T1 value at 3.0 Tesla is a sensitive marker of diffuse myocardial damage. We evaluated the clinical usefulness of native T1 mapping in symptomatic adults with congenital heart disease (CHD), particularly in the systemic right ventricle (RV). Prospectively, 45 consecutive symptomatic adults with CHD were enrolled: 20 with systemic RV and 25 with tetralogy of Fallot underwent cardiac magnetic resonance (CMR) imaging at 3.0 Tesla. The Modified Look-Locker Inversion recovery sequence was used for T1 mapping. Cardiovascular events in the systemic RV were defined as heart failure and tachyarrhythmia. Brain natriuretic peptide (BNP) and indexed systemic ventricular end-diastolic volume were significantly higher in the systemic RV group. The native T1 value and extracellular volume (ECV) of the septal and lateral walls were higher in the systemic RV group, suggesting high impairment of the myocardium in the systemic RV group. There was a strong correlation between the native T1 value and ECV of the septum (r = 0.58, P = 0.03) and lateral wall (r = 0.56, P = 0.046) in the systemic RV group. Seven patients with systemic RV had cardiovascular events. In univariate logistic regression analysis, BNP and native T1 values of the insertion point were important for predicting cardiovascular events. The native T1 value at 3.0 Tesla may be a sensitive, contrast-free, and non-invasive adjunct marker of myocardial damage in CHD and predictive of cardiovascular events in the systemic RV.

Phase analysis of gated PET in the evaluation of mechanical ventricular synchrony: A narrative overview

Noninvasive imaging modalities offer the possibility to dynamically evaluate cardiac motion during the cardiac cycle by means of ECG-gated acquisitions. Such motion characterization along with orientation, segmentation preprocessing, and ultimately, phase analysis, can provide quantitative estimates of ventricular mechanical synchrony. Current evidence on the role of mechanical synchrony evaluation is mainly available for echocardiography and gated single-photon emission computed tomography, but less is known about the utilization of gated positron emission tomography (PET). Although data available are sparse, there is indication that mechanical synchrony evaluation can be of diagnostic and prognostic values in patients with known or suspected coronary artery disease-related myocardial ischemia, prediction of response to cardiac resynchronization therapy, and estimation of risk for adverse cardiac events in patients' heart failure. As such, the evaluation of mechanical ventricular synchrony through phase analysis of gated acquisitions represents a value addition to modern cardiac PET imaging modality, which warrants further research and development in the evaluation of patients with cardiovascular disease.

Prognostic implications of late gadolinium enhancement at the right ventricular insertion point in patients with non-ischemic dilated cardiomyopathy: A multicenter retrospective cohort study

Introduction

The presence of late gadolinium enhancement (LGE) at the right ventricular insertion point (RVIP) on cardiac magnetic resonance (CMR) is generally believed to be nonspecific, but the clinical implication of this unique LGE pattern in patients with non-ischemic dilated cardiomyopathy (NICM) has not been elucidated.

Objectives

We investigated the prognostic significance of RVIP-LGE in NICM patients.

Methods

A total of 360 consecutive NICM patients referred for CMR (102 with no LGE, 50 with RVIP-LGE, 121 with left ventricular [LV]-LGE, and 87 with both an LV and RVIP-LGE) were studied. The primary endpoint was a composite of the all-cause death, hospitalization due to worsening of heart failure, and major arrhythmic events.

Results

During a mean follow-up of 45.2 ± 36.5 months, 149 (41.4%) patients (22 [21.6%] no LGE vs. 16 [32.0%] RVIP-LGE vs. 62 [51.2%] LV-LGE vs. 49 [56.3%] both LV and RVIP-LGE, P < 0.0001) reached the primary endpoint. A Kaplan Meier curve demonstrated that RVIP-LGE patients had an intermediate trend of an event free survival rate for the composite endpoint (log-rank P < 0.0001). In a multivariable Cox regression model, LV-LGE (P = 0.008) and both LV and RVIP-LGE (P = 0.003) were significantly associated with a worse outcome, whereas RVIP-LGE was not (P = 0.101). In addition, RVIP-LGE patients (n = 32) had a more favorable outcome compared to LV-LGE patients (n = 32) even after matching the extent of the LGE (median 3.4% [interquartile range, 3.1–3.8], 8 [25.0%] RVIP-LGE vs. 20 [62.5%] LV-LGE, P = 0.002).

Conclusions

LGE confined to the RVIP among NICM patients did not significantly increase the risk of adverse cardiac events, and also showed a better outcome than the same extent of LGE located in the LV. Identification of this unique LGE distribution may help refine the current risk stratification.

Impact of high-intensity endurance exercise on regional left and right ventricular myocardial mechanics

Aims

Strenuous endurance exercise acutely increases myocardial wall stress and evokes transient functional cardiac perturbations. However, it is unclear whether exercise-induced functional cardiac disturbances are ubiquitous throughout the myocardium or are segment specific. The aim of this study was to examine the influence of high-intensity endurance exercise on global and segmental left (LV) and right (RV) ventricular tissue deformation (strain).

Methods and results

Echocardiography was used to measure strain in 23 active men (age: 28 ± 2 years; VO2 peak: 4.5 ± 0.7 L min-1) at rest and during a standardized low-intensity exercise challenge, before and after a 90-min high-intensity endurance cycling intervention. Following the cycling intervention, LV and RV global strain decreased at rest (LV: -18.4 ± 0.4% vs. -17.7 ± 0.4%, P < 0.05; RV: -27.6 ± 0.7% vs. -26.4 ± 0.6%, P < 0.05) and by a greater extent during the low-intensity exercise challenge (LV: -21.3 ± 0.4% vs. -19.2 ± 0.5%, P < 0.01; RV: -28.4 ± 0.8% vs. -23.5 ± 0.9%, P < 0.01). Reductions in LV strain were unique to regions of RV attachment (e.g. LV septum: -24.4 ± 0.5% vs. -21.4 ± 0.6%, P < 0.01) with lateral (-18.9 ± 0.4% vs. -18.4 ± 0.5%) and posterior segments (-19.5 ± 0.4% vs. -18.8 ± 0.7%) unaffected. Similarly, augmentation of strain from rest to exercise was abolished in the RV free wall (-1.1 ± 1.0% vs. 2.9 ± 1.2%, P < 0.01), reduced in the septum (-4.6 ± 0.4% vs. -2.4 ± 0.5%, P < 0.01), and unchanged in the lateral (-1.2 ± 0.6% vs. -0.9 ± 0.6%) and posterior walls (-1.7 ± 0.6% vs. -1.3 ± 0.7%).

Conclusion

Changes in ventricular strain following high-intensity exercise are more profound in the right ventricle than in the left ventricle. Reductions in LV strain were unique to the septal myocardium and may reflect ventricular interactions secondary to exercise-induced RV dysfunction.

Diffuse Myocardial Interstitial Fibrosis and Dysfunction in Early Chronic Kidney Disease

Patients with chronic kidney disease (CKD) have a disproportionately high risk of cardiovascular (CV) morbidity and mortality from the very early stages of CKD. This excess risk is believed to be the result of myocardial disease commonly termed uremic cardiomyopathy (UC). It has been suggested that interstitial myocardial fibrosis progresses with advancing kidney disease and may be the key mediator of UC. This longitudinal study reports data on the myocardial structure and function of 30 patients with CKD with no known cardiovascular disease and healthy controls. All patients underwent cardiac magnetic resonance imaging including T1 mapping and late gadolinium enhancement (if estimated glomerular filtration rate > 30 ml/min/1.73 m²). Over a mean follow-up period of 2.7 ± 0.8 years, there was no change in left ventricular mass, volumes, ejection fraction, native myocardial T1 times, or extracellular volume with CKD or in healthy controls. Global longitudinal strain (20.6 ± 2.9 s⁻¹ vs 19.8 ± 2.9 s⁻¹, p = 0.03) and mitral annular planar systolic excursion (13 ± 2 mm vs 12 ± 2 mm, p = 0.009) decreased in CKD but were clinically insignificant. Midwall late gadolinium enhancement was present in 4 patients at baseline and was unchanged at follow-up. Renal function was stable in this cohort over follow-up (change in estimated glomerular filtration rate was −3 ml/min/1.73 m²) with no adverse clinical CV events. In conclusion, this study demonstrates that in a cohort of patients with stable CKD, left ventricular mass, native T1 times, and extracellular volume do not increase over a period of 2.7 years.