Predictive Value of Left Atrial Strain for Thrombotic Events in Hypertrophic Cardiomyopathy without Atrial Fibrillation.

Purpose To assess the predictive value of left atrial (LA) fast long-axis strain derived from cardiac MRI for thrombotic events (TEs) in individuals with hypertrophic cardiomyopathy (HCM). Materials and Methods This secondary analysis of an ongoing prospective trial (Chinese Clinical Trial Registry: ChiCTR1900024094) included consecutive participants with HCM without atrial fibrillation (AF) who underwent cardiac MRI from January 2012 to December 2020. The LA fast long-axis strain was obtained by semiautomatically tracking the distance between the atrioventricular junction and the midposterior LA wall. The primary end point was the occurrence of TEs, including ischemic stroke, transient ischemic attack, and systemic thromboembolism. The predictive value of LA strain was determined with Cox analysis. Results Overall, 714 participants with HCM (mean age ± SD, 50.1 years ± 14.3; 441 men, 273 women; obstructive HCM, n = 289; apical HCM, n = 144) were included (median follow-up: 51 months). Twenty-eight (3.9%) participants with HCM experienced TEs, 60% (17 of 28) of whom had no new-onset AF. Those who experienced TEs had lower LA reservoir and conduit strains (16.2% ± 7.3 vs 21.8% ± 8.3, P = .001; 5.9% ± 3.5 vs 9.7% ± 5.5, P = .01, respectively), with no evidence of a difference in LA booster strain between groups. LA reservoir and conduit strain were independent predictors of TEs in different multivariable models, even after adjusting for age, diabetes, and left ventricular ejection fraction (adjusted hazard ratios: reservoir strain [per 5% decrease], 1.29-1.34 [95% CI: 1.05, 1.50]; conduit strain [per 5% decrease], 1.42-1.47 [95% CI: 1.04, 1.67]). Conclusion Cardiac MRI-derived LA reservoir and conduit strain were independent predictors for the occurrence of TEs in individuals with HCM without AF. Keywords: MR-Imaging, Left Atrium, Cardiomyopathies, Hypertrophic Cardiomyopathy, Thromboembolism, Cardiac Magnetic Resonance Chinese Clinical Trial Registry no. ChiCTR1900024094 Supplemental material is available for this article. © RSNA, 2025.