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

Abstract

SummaryTo achieve further risk stratification in hypertrophic cardiomyopathy (HCM) patients, we localized and quantified layer-specific LVM fibrosis on MRI in HCM patients using regional layer-specific peak longitudinal strain (PLS) and peak circumferential strain (PCS) in LV myocardium (LVM) on speckle tracking transthoracic echocardiography (TTE). A total of 18 HCM patients (14 males; 58 ± 17 years) underwent 1.5T-MRI and TTE. PLS and PCS in each layer of the LVM (endocardium, epicardium, and whole-layer myocardium) were calculated for 17 AHA-defined lesions. MRI assessment showed that fibrosis was classified as endocardial, epicardial, or whole-layer (= either or both of these). Regional PLS was smaller in fibrotic endocardial lesions than in non-fibrotic endocardial lesions (P = 0.004). To detect LV endocardial lesions with fibrosis, ROC curves of regional PLS revealed an area under the curve (AUC) of 0.609 and a best cut-off point of 13.5%, with sensitivity of 65.3% and specificity of 54.3%. Regional PLS was also smaller in fibrotic epicardial lesions than in nonfibrotic epicardial lesions (P < 0.001). To detect LV epicardial lesions with fibrosis, ROC curves of PLS revealed an AUC of 0.684 and a best cut-off point of 9.5%, with sensitivity of 73.5% and specificity of 55.5%. Using whole-layer myocardium analysis, PLS was smaller in fibrotic lesions than in non-fibrotic lesions (P < 0.001). To detect whole-layer LV lesions with fibrosis, ROC curves of regional PLS revealed an AUC of 0.674 and a best cut-off point of 12.5%, with sensitivity of 79.0% and specificity of 50.7%. There were no significant differences in PCS of LV myocardium (endocardium, epicardium, and whole-layer) between fibrotic and nonfibrotic lesions. Quantitative regional PLS but not PCS in LV endocardium, epicardium, and whole-layer myocardium provides useful non-invasive information for layer-specific localization of fibrosis in HCM patients.(Int Heart J 2018; 59: 523-530) Key words: Left ventricular myocardium, Layer-specific peak longitudinal strain, Speckle tracking transthoracic echocardiography, Magnetic resonance imaging R isk stratification for major adverse cardiac events (MACE) including sudden death is important for the management of patients with hypertrophic cardiomyopathy (HCM) because it has been established that implantable cardioverter defibrillators for preventing sudden cardiac death are effective. 1)Occurrence of non-sustained ventricular tachycardia (VT)2) and detection of late enhancement (LE) in left ventricular (LV) myocardium suggesting the presence of myocardial fibrosis, by T1 weighted cardiac magnetic resonance imaging (MRI), 3,4) are very useful predictors for MACE in HCM patients as well as non-dilated LV size and mitral regurgitation 5) and dilated phase HCM. 6) Furthermore, the genetic variation in the SCN10A gene might be associated with cardiac conduction abnormalities in HCM patients.7) However, current stratification algorithms remain incomplete and novel non-invasive strategies are needed in order to ef...

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

“…These regional strain abnormalities may be related to areas with higher percentage of fibrosis on magnetic resonance imaging, being a potential substrate for the development of arrhythmias. 23,24 Diastolic dysfunction was more evident in hypertensive patients in this sample. Hypertensive patients had a higher percentage of grade I or II dysfunction and a lower percentage of undetermined cases, according to the latest recommendations for diastolic function evaluation.…”

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

“…8) Tissue doppler imaging and magnetic resonance imaging have been used to obtain insight into layer-specific differences in myocardial function. [9][10][11][12] However, most of these techniques are not widely available and their application is time consuming.…”