Myocardial Scar by Pulse-Cancellation Echocardiography Is Independently Associated with Appropriate Defibrillator Intervention for Primary Prevention after Myocardial Infarction

Post-myocardial infarction fibrosis: Pathophysiology, examination, and intervention

Cardiac fibrosis plays an indispensable role in cardiac tissue homeostasis and repair after myocardial infarction (MI). The cardiac fibroblast-to-myofibroblast differentiation and extracellular matrix collagen deposition are the hallmarks of cardiac fibrosis, which are modulated by multiple signaling pathways and various types of cells in time-dependent manners. Our understanding of the development of cardiac fibrosis after MI has evolved in basic and clinical researches, and the regulation of fibrotic remodeling may facilitate novel diagnostic and therapeutic strategies, and finally improve outcomes. Here, we aim to elaborate pathophysiology, examination and intervention of cardiac fibrosis after MI.

Power Modulation Echocardiography to Detect and Quantify Myocardial Scar

BACKGROUND

Myocardial scar correlates with clinical outcomes. Traditionally, late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) is used to detect and quantify scar. In this prospective study using LGE CMR as reference, the authors hypothesized that nonlinear ultrasound imaging, namely, power modulation, can detect and quantify myocardial scar in selected patients with previous myocardial infarction. In addition, given the different histopathology between ischemic and nonischemic scar, a further aim was to test the diagnostic performance of this echocardiographic technique in unselected consecutive individuals with ischemic and nonischemic LGE or no LGE on CMR.

METHODS

Seventy-one patients with previous myocardial infarction underwent power modulation echocardiography following CMR imaging (group A). Subsequently, 101 consecutive patients with or without LGE on CMR, including individuals with nonischemic LGE, were scanned using power modulation echocardiography (group B).

RESULTS

In group A, echocardiography detected myocardial scar in all 71 patients, with good scar volume agreement with CMR (bias = -1.9 cm³; limits of agreement [LOA], -8.0 to 4.2 cm³). On a per-segment basis, sensitivity was 82%, specificity 97%, and accuracy 92%. Sensitivity was higher in the inferior and posterior segments and lower in the anterior and lateral walls. In group B, on a per-subject basis, the sensitivity of echocardiography was 62% (91% for ischemic and 30% for nonischemic LGE), with specificity and accuracy of 89% and 72%, respectively. The bias for scar volume between modalities was 5.9 cm³, with LOA of 34.6 to 22.9 cm³ (bias = -1.9 cm³ [LOA, -11.4 to 7.6 cm³] for ischemic LGE, and bias = 18.9 cm³ [LOA, -67.4 to 29.7.6 cm³] for nonischemic LGE).

CONCLUSIONS

Power modulation echocardiography can detect myocardial scar in both selected and unselected individuals with previous myocardial infarction and has good agreement for scar volume quantification with CMR. In an unselected cohort with nonischemic LGE, sensitivity is low.

Echocardiographic Advances in Dilated Cardiomyopathy

Although the overall survival of patients with dilated cardiomyopathy (DCM) has improved significantly in the last decades, a non-negligible proportion of DCM patients still shows an unfavorable prognosis. DCM patients not only need imaging techniques that are effective in diagnosis, but also suitable for long-term follow-up with frequent re-evaluations. The exponential growth of echocardiography’s technology and performance in recent years has resulted in improved diagnostic accuracy, stratification, management and follow-up of patients with DCM. This review summarizes some new developments in echocardiography and their promising applications in DCM. Although nowadays cardiac magnetic resonance (CMR) remains the gold standard technique in DCM, the echocardiographic advances and novelties proposed in the manuscript, if properly integrated into clinical practice, could bring echocardiography closer to CMR in terms of accuracy and may certify ultrasound as the technique of choice in the follow-up of DCM patients. The application in DCM patients of novel echocardiographic techniques represents an interesting emergent research area for scholars in the near future.

Magnetic Resonance Assessment of Ejection Fraction Versus Echocardiography for Cardioverter-Defibrillator Implantation Eligibility

Simple Summary

Nonischemic cardiomyopathies with low left ventricular ejection fractions (LVEF) are eligible for an implantable cardioverter defibrillator. However, the guidelines do not specify which method should be used to assess LVEF. In our study we investigated the potential impact of performing two-dimensional echocardiography (2DE) compared to cardiovascular magnetic resonance (CMR) for LVEF regarding ICD eligibility. We found that 2DE both overestimated and especially underestimated the need for implantation, which can have serious implications in the quality of life and the prevention of death events.

Abstract

Background: The aim of this study was to investigate the potential impact of performing two-dimensional echocardiography (2DE) compared to cardiovascular magnetic resonance (CMR) for left ventricular ejection fraction (LVEF) on implantable cardioverter defibrillator (ICD) eligibility. Methods: A prospective cohort of 166 consecutive patients with nonischemic cardiomyopathy (NICM) was designed to compare transthoracic 2DE and CMR imaging. Results: Echocardiography measurements have important differences and large limits of agreement compared to CMR, especially when assessing ventricle volumes, and smaller but relevant differences when assessing LVEF. The agreement between CMR and 2DE regarding the identification of subjects with EF <= 35, respectively <= 30, and thus eligible for an ICD measured by Cohen’s Kappa was 0.78 (95% CI: 0.68–0.88), p < 0.001, respectively 0.65 (95% CI: 0.52–0.78), p < 0.001. The disagreement represented 7.9%/11.3% of the subjects who had EF < 35%/< 30% as observed by CMR, who would have been classified as eligible for an ICD, resulting in an additional need to use an ICD. Moreover, 2.6%/3.3% would have been deemed eligible by echocardiography for an ICD. Conclusions: These measurement problems result in incorrect assignments of eligibility that may have serious implications on the quality of life and the prevention of death events for patients assessed for eligibility of an ICD.

Pulse-Cancellation Echocardiography for Clinical Evaluation of Myocardial Scar Burden

PURPOSE OF REVIEW

Echocardiography has been completely abandoned as far as myocardial tissue characterization is concerned, but recently, the possibility to detect scarred myocardial tissue has been revived. We review the most recent studies aiming to assess the presence of myocardial fibrosis or scar using echocardiography.

RECENT FINDINGS

The use of a simple and clinically available ultrasound, such as method pulse-cancellation, is a promising add-on to standard echocardiography for the detection of scarred myocardial tissue, mostly, but not only, in the setting of post-myocardial infarction patients. Pulse-cancellation technique, available since at least 20 years ago on commercial ultrasound machines, is reasonably accurate to detect myocardial scar tissue caused by recent or prior myocardial infarction, the accuracy varying depending on the spatial distribution of myocardial scars in the left ventricle. Severe myocardial fibers disarray, as found in hypertrophic cardiomyopathy, can also be detected by this ultrasound method.