Quantitative Differentiation of LV Myocardium with and without Layer-Specific Fibrosis Using MRI in Hypertrophic Cardiomyopathy and Layer-Specific Strain TTE Analysis

Predicting Left Ventricular Myocardial Fibrosis in Patients with Hypertrophic Cardiomyopathy by Speckle Tracking Automated Functional Imaging

OBJECTIVE

The study was performed to explore the predictive value of multiple strain parameters for myocardial fibrosis in patients with hypertrophic cardiomyopathy (HCM) by using speckle tracking automated functional imaging (AFI).

METHODS

A total of 61 patients diagnosed with HCM were finally enrolled in this study. All patients completed transthoracic echocardiography and cardiac magnetic resonance late gadolinium enhancement (LGE) within 1 month. Twenty age- and sex-matched healthy participants were included as the control group. Multiple parameters, including segmental longitudinal strain (LS), global longitudinal strain (GLS), post-systolic index and peak strain dispersion, were automatically analyzed by AFI.

RESULTS

A total of 1458 myocardial segments were analyzed according to the left ventricular 18-segment model. Among the 1098 segments from HCM patients, segments with LGE had a lower absolute value of segmental LS than those without LGE (p < 0.05). The cutoff values of segmental LS for predicting positive LGE in the basal, intermediate and apical regions were -12.5%, -11.5% and -14.5%, respectively. GLS could predict significant myocardial fibrosis (≥2 positive LGE segments) at a cutoff value of -16.5% with a sensitivity of 80.9% and specificity of 76.5%. As an independent predictor of significant myocardial fibrosis, GLS was substantially associated with the severity of myocardial fibrosis and 5 years sudden cardiac death risk score in HCM patients.

CONCLUSION

Speckle tracking AFI could efficiently identify left ventricular myocardial fibrosis in patients with HCM by multiple parameters. GLS predicted significant myocardial fibrosis at a cutoff value of -16.5%, which may indicate the adverse clinical outcomes in HCM patients.

Fibrosis in hypertrophic cardiomyopathy: role of novel echo techniques and multi-modality imaging assessment

Hypertrophic cardiomyopathy (HCM) represents one of the primary cardiomyopathies and may lead to heart failure and sudden cardiac death. Among various histologic features of the disease examined, assessment of myocardial fibrosis may offer valuable information, since it may be considered the common nominator for all HCM connected complications. Late gadolinium-enhanced cardiac magnetic resonance (LGE-CMR) has emerged as the reference noninvasive method for visualizing and quantifying myocardial fibrosis in patients with HCM. T1 mapping, a promising new CMR technique, may provide an advantage over conventional LGE-CMR, by permitting a more valid quantification of diffuse fibrosis. On the other hand, echocardiography offers a significantly more portable, affordable, and easily accessible solution for the study of fibrosis. Various echocardiographic techniques ranging from integrated backscatter and contrast-enhanced ultrasound to two- (2D) or three-dimensional (3D) deformation and shear wave imaging may offer new insights into substrate characterization in HCM. The aim of this review is to describe thoroughly all different modalities that may be used in everyday clinical practice for HCM fibrosis evaluation (with special focus on echocardiographic techniques), to concisely present available evidence and to argue in favor of multi-modality imaging application. It is essential to understand that the role of various imaging modalities is not competitive but complementary, since the information provided by each one is necessary to illuminate the complex pathophysiologic pathways of HCM, offering a personalized approach and treatment in every patient.

Evaluation of isolated left ventricular noncompaction using cardiac magnetic resonance tissue tracking in global, regional and layer-specific strains

We used cardiac magnetic resonance tissue tracking (CMR-TT) to quantitatively analyze the global, regional and layer-specific strain of isolated left ventricular noncompaction (ILVNC). Combined with late gadolinium enhancement (LGE), we initially explored the effect of focal myocardial fibrosis on myocardial strain. CMR was performed in 63 patients with ILVNC and 52 patients without ILVNC (i.e., the control group). The ILVNC group was divided into an LGE(+) group (29 patients) and an LGE(−) group (34 patients) according to the presence or absence of late gadalinum enhancement (LGE). CVI42 software was used to measure global and regional (basal, middle, apical) radial strain (RS), circumferential strain (CS), longitudinal strain (LS), subendocardial LS and subepicardial LS. The basal–apical strain gradient was defined as the apical mean strain minus the basal mean strain. We then compared differences between these strain parameters. The subendocardial-subepicardial LS gradient was defined as the maximum subendocardial LS minus the subepicardial LS. Compared with the control group, the global and regional RS, CS, LS and the subendocardial, subepicardial LS of the ILVNC group were significantly diminished (P < 0.01). Compared with the LGE(−) group, the global and regional RS, CS, LS and the subendocardial, subepicardial LS of the LGE(+) group were significantly diminished (P < 0.05). In the ILVNC group, the basal–apical CS and LS gradient, and the subendocardial-subepicardial LS gradient were significantly lower than those in the control group (P < 0.01). There were significant differences in myocardial strain between patients with and without ILVNC. ILVNC revealed a specific pattern in terms of strain change. The myocardial strain of the cardiac apex and endocardium was significantly lower than that of the cardiac base and epicardium, respectively. Myocardial strain reduction was more significant in ILVNC patients with focal myocardial fibrosis.

[Chronic pheochromocytoma-induced myocardial injuries: What should we expect from modern and classical echocardiographic tools?]

INTRODUCTION

Pheochromocytoma is a rare disease, which may manifest as severe cardiac complications. Apart from these situations, the "chronic" cardiac impact is not clearly defined. A cardiac MRI study suggests that these patients are carrying areas of fibrosis and foci of left ventricular myocarditis. Since these abnormalities are usually associated with altered left ventricular longitudinal systolic strain, we hypothesize that this strain is altered in patients with a "chronic" pheochromocytoma.

METHOD

This retrospective case-control study was performed using patients from the Bordeaux University Hospital database, included between 2008 and 2016. We compared the left ventricular global longitudinal strain (GLS), radial and circumferential systolic strain and classic echocardiographic parameters between patients with pheochromocytoma and controls matched for age, sex, body mass index and systolic blood pressure.

RESULTS

The analysis included 47 patients and 47 correctly matched controls. There were no statistically significant differences between the 2 groups in terms of GLS (-20.7±2.4% vs. -20.2±2.7%, P=0.40), radial strain, left ventricular mass or diastolic function. Left ventricular ejection fraction and circumferential strain were significantly higher in patients than in controls, with a significantly lower telediastolic diameter.

CONCLUSION

No significant changes in GLS were observed in our pheochromocytoma patients, compared with controls. Several hypotheses may explain these results. The presence of fibrosis foci and areas of left ventricular myocarditis being associated with a poor cardiological prognosis, a systematic cardiac MRI could be discussed in these patients, until further studies are performed.

Assessment of left ventricular systolic function in hypertrophic cardiomyopathy patients with myocardial injury: a study based on layer-specific speckle tracking echocardiaography

We conducted this study to investigate left ventricle (LV) systolic function in endocardial, mid-myocardial, and epicardial layers by two-dimensional (2D) speckle tracking echocardiography (STE) in hypertrophic cardiomyopathy (HCM) patients with myocardial injury indexed by elevated serum cardiac troponin I (cTnI). Twenty-nine HCM patients with myocardial injury, thirty-five HCM patients without myocardial injury, and ninty-one healthy controls were enrolled in this study. Serum cTnI > 0.026 ng/mL was defined as myocardial injury. LV longitudinal and circumferential strain (LS and CS) were assessed in endocardial, mid-myocardial and epicardial layers. Layer-specific LS and CS differed significantly (all P < 0.001) among all three groups in all three layers, in a descending order from healthy controls to HCM patients without myocardial injury to HCM patients with myocardial injury. Layer-specific LS and CS were decreased the most in HCM patients with myocardial injury indexed by elevated seum cTnI (all P < 0.05). In HCM patients with myocardial injury, layer-specific LS and CS were significantly lower in the segments with greater hypertrophy (segmental thickness ≥ 15 mm) (all P < 0.001) except for endocardial CS (P > 0.05). Layer-specific evaluation of LV strain may improve understanding of impaired LV systolic function in HCM patients with myocardial injury, thus preventing further damage.

Strain Analysis of Left Ventricular Function in the Association of Hypertrophic Cardiomyopathy and Systemic Arterial Hypertension

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is the most common heart disease of genetic origin in the world population, with a prevalence of at least 1/500. The association with systemic arterial hypertension (SAH) is not uncommon, as it affects approximately 25% of the world population. Most studies aim at the differential diagnosis between these diseases, but little is known about the magnitude of this association.

OBJECTIVE

To compare left ventricular global longitudinal strain (GLS) in HCM patients with and without associated SAH.

METHODS

Retrospective cross-sectional study that included 45 patients with HCM and preserved ejection fraction, with diagnosis confirmed by magnetic resonance imaging, including 14 hypertensive patients. Transthoracic echocardiography was performed, with emphasis on left ventricular myocardial strain analysis using GLS. In this study, p < 0.05 was considered statistically significant.

RESULTS

Left ventricular strain was significantly lower in hypertensive individuals compared to normotensive individuals (-10.29 ± 2.46 vs. -12.35% ± 3.55%, p = 0.0303), indicating greater impairment of ventricular function in that group. Mean age was also significantly higher in hypertensive patients (56.1 ± 13.9 vs. 40.2 ± 12.7 years, p = 0.0001). Diastolic dysfunction was better characterized in hypertensive patients (p = 0.0242).

CONCLUSION

Myocardial strain was significantly lower in the group of patients with HCM and SAH, suggesting greater impairment of ventricular function. This finding may be related to a worse prognosis with early evolution to heart failure. Prospective studies are required to confirm this hypothesis.

Early Assessment of Left Ventricular Function by Layer-Specific Strain and Its Relationship to Pulsatile Arterial Load in Patients with Coronary Slow Flow

Previous studies reported a controversial left ventricular (LV) function impairment and pathophysiology in patients with coronary slow flow (CSF). Greater arterial load has been shown to increase aortic impedance and endothelial shear stress, potentially affecting coronary anatomy and function. We investigated LV systolic function by a new layer-specific strain technology and assessed the association between pulsatile arterial load and contractility.A total of 70 patients with CSF and 50 controls with normal coronary angiography were included in the study. Layer-specific longitudinal and circumferential strains were assessed from endocardium, mid-myocardium, and epicardium (global longitudinal strain (GLS)-endo, GLS-mid, GLS-epi and GCS-endo, GCS-mid, GCS-epi) by two-dimensional speckle tracking imaging (2D-STI). Pulsatile arterial load was estimated by indexed arterial compliance (ACI). Layer-specific GLS showed a decreasing gradient from the endocardium to the epicardium in both the controls and CSF group. GLS-endo and GLS-mid in the CSF group were significantly lower than the control group (all P < 0.05). Layer-specific longitudinal strain showed a good correlation with the number of affected coronary arteries (all P < 0.05) and the mean thrombolysis in the myocardial infarction frame count (TFC) (all P < 0.05). ACI was lower in patients with CSF (P = 0.005), and ACI was correlated negatively with layer-specific GLS (all P < 0.05).Layer-specific evaluation of the LV provides an understanding of the layer-specific properties of the LV wall and the possible process of the LV impairment in patients with CSF. Greater pulsatile arterial load, as manifested by a lower ACI, is coupled with worse LV longitudinal function in patients with CSF.