Echocardiographic parameters of cardiac structure and function in the diagnosis of acute myocarditis in adult patients: A systematic review and meta-analysis

Abstract

Background: Transthoracic echocardiography (TTE) plays a key role in the initial work-up of myocarditis where the identification of pathologic structural and functional changes may assist in its diagnosis and management. The aim of this systematic review was to appraise the evidence for the utility of echocardiographic parameters of cardiac structure and function in the diagnosis of myocarditis in adult populations.

Methods: A systematic literature search of medical databases was performed using PRISMA principles to identify all relevant studies assessing TTE parameters in adult patients with myocarditis (1995-2020; English only; PROSPERO registration CRD42021243598). Data for a range of structural and functional TTE parameters were individually extracted and those with low heterogeneity were then meta-analyzed using a random-effects model for effect size, and assessed through standardized mean difference (SMD).

Results: Available data from six studies (with a pooled total of 269 myocarditis patients and 240 controls) revealed that myocarditis can be reliably differentiated from healthy controls using echocardiographic measures of left ventricular (LV) size and systolic function, in particular LV end-diastolic diameter, LV ejection fraction (LVEF) and LV global longitudinal strain (LV-GLS) (p ≤ .01 for all). LV-GLS demonstrated the highest overall effect size, followed by LVEF and LVEDD (SMD: |0.46-1.98|). Two studies also demonstrated that impairment in LV-GLS was associated with adverse cardiovascular outcomes in this population, irrespective of LVEF.

Conclusions: LV-GLS demonstrated the greatest overall effect size and therefore ability to differentiate myocarditis populations from healthy controls. GLS was also shown to be a predictor of adverse cardiovascular outcomes, in this population.

Hightlights: What is already known on this subject? Myocarditis is a disease process that is often a diagnosis of exclusion, as it frequently mimics other acute cardiac pathologies. Transthoracic echocardiography is traditionally the initial imaging modality used for noninvasive structural assessment in populations with myocarditis. What might this study add? This study demonstrates that left ventricular (LV) global longitudinal strain, LV ejection fraction and LV end-diastolic diameter can differentiate between myocarditis patients and healthy controls. LV-GLS demonstrated the greatest overall effect size when comparing these two populations, in comparison to the other measures. How might this impact on clinical practice? This study demonstrates that assessment of myocardial deformation indices allows for sensitive discrimination between myocarditis patients from healthy controls. Routine assessment of LV-GLS may serve as an important diagnostic tool in the acute care setting.

Keywords: LV-GLS; LVEDD; LVEF; myocarditis; non-invasive cardiac imaging; speckle tracking echocardiography; transthoracic echocardiography.