Power Modulation Echocardiography to Detect and Quantify Myocardial Scar

Abstract

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.

Keywords: CMR imaging; Cardiovascular magnetic resonance imaging; Ischemic LGE; Myocardial scar; Nonischemic LGE; Power modulation echocardiography.