Prognostic value of left atrial strain analysis in patients with chronic myocarditis

BACKGROUND: Left atrial (LA) strain and left atrioventricular coupling index (LACI) independently predict prognosis in multiple cardiovascular diseases, but their prognostic value in chronic myocarditis remains unclear. This study aimed to evaluate the prognostic value of CMR-derived LA strain and LACI in patients with chronic myocarditis. METHODS: This single-center retrospective study included patients suspected of chronic myocarditis who underwent CMR from June 2019 to October 2024. CMR-derived LA functional parameters, LACI, as well as clinical characteristics and outcomes were collected. Composite endpoints included major adverse cardiovascular events and arrhythmia (including ventricular premature beats and intraventricular conduction block). Multivariable Cox regression identified predictive parameters. RESULTS: A total of 113 patients (mean age 50 ± 12 years; 62 males) were enrolled. After a median follow-up of 24 months, 17 (15.0%) patients experienced composite events. Multivariable Cox regression showed that LA reservoir strain (adjusted HR = 0.770, 95%CI: 0.631-0.894, P = 0.003) and LA conduit strain (adjusted HR = 0.770, 95%CI: 0.615-0.911, P = 0.007) were independent predictors of composite events. LA reservoir strain and LA conduit strain had high negative predictive values (98.6% and 97.5%, respectively) and sensitivities (94.1% and 88.2%, respectively) for ruling out composite events, with statistical significance. The integrated model incorporating traditional CMR parameters, LARS, and LACS exhibited the best predictive performance (AUC=0.906, 95% CI: 0.788-0.973). CONCLUSION: CMR-derived LA reservoir and conduit strains are independent predictors of adverse clinical outcomes in patients with chronic myocarditis, serving as reliable "rule-out" tools for composite events. Additionally, the combined model of these two strains exhibits excellent predictive performance for composite events.