Incremental Prognostic Value of Left Atrial Strain in Patients With Suspected Myocarditis and Preserved Left Ventricular Ejection Fraction

Abstract

Background: Analysis of left atrial (LA) strain and left atrioventricular coupling index (LACI) have prognostic value in cardiovascular diseases. However, the prognostic value of LA strain and LACI in patients with suspected myocarditis and preserved left ventricular ejection fraction (LVEF) is unclear.

Purpose: To investigate the prognostic value of LA strain and LACI in patients with suspected myocarditis and preserved LVEF in comparison with conventional MRI outcome predictors.

Study type: Retrospective.

Population: One hundred sixty-five patients with clinically suspected myocarditis and preserved LVEF with available follow-up data.

Field strength/sequence: Steady-state free precession cine and phase-sensitive inversion recovery segmented gradient echo late gadolinium enhancement sequences at 3.0 T.

Assessment: Left ventricular (LV) and LA strain were evaluated using feature tracking. LACI was calculated as the ratio of LA and LV volumes at LV end-diastole. Patients were followed-up with the primary endpoint being major adverse cardiovascular events (MACE).

Statistical tests: Independent-samples t-test and Mann-Whitney U test to compare patients with and without MACE, receiver operating characteristic (ROC) curve analysis to define high/low risk groups, Kaplan-Meier survival analysis and Cox proportional hazards regression to assess prognosis. A P value of <0.05 was considered statistically significant.

Results: The associations of LV strain parameters (including global radial, circumferential, and longitudinal strain) and LACI with MACE were not significant (P = 0.511, 0.108, 0.148, and 0.847, respectively). An optimal LA conduit strain (Ԑe) cutoff value of 10.4% was identified to best classify patients into low- and high-risk groups. Only Ԑe was significantly associated with MACE in both univariable (hazards ratio [HR] 0.936, 95% confidence interval [CI] 0.884-0.991) and multivariable Cox survival analyses (HR 0.937, 95% CI 0.884-0.994).

Data conclusion: LA conduit strain has prognostic value in patients with suspected myocarditis and preserved LVEF, incremental to conventional MRI outcome predictors, whereas LACI was not associated with MACE occurrence.

Evidence level: 3 TECHNICAL EFFICACY: Stage 2.

Keywords: feature tracking; left atrial strain; myocarditis.