Left Atrial Strain Prediction of New-Onset Atrial Fibrillation in Apical Hypertrophic Cardiomyopathy with Cardiac MRI.

Purpose To evaluate the predictive value of cardiac MRI-derived left atrial strain (LAS) for new-onset atrial fibrillation (AF) in apical hypertrophic cardiomyopathy (AHCM). Materials and Methods This retrospective study included patients with AHCM with no prior history of AF who underwent 3.0-T cardiac MRI between May 2016 and December 2023. LAS parameters-reservoir strain (εs), conduit strain (εe), and booster pump strain (εa)-and minimum left atrial volume index (LAVImin) were measured. The clinical end point was new-onset AF as confirmed with electrocardiography, Holter monitoring, or implantable cardiac devices. Cox proportional hazards models and time-dependent receiver operating characteristic (ROC) analyses were performed to evaluate associations and discriminatory performance for new-onset AF. Results A total of 156 patients (mean age, 51.0 years ± 11.5 [SD]; 113 male) were included. During a median follow-up of 33 months, AF occurred in 21 patients. In multivariable Cox models adjusted for age, body mass index, and LAVImin, LAS parameters were independently associated with incident AF (εs: hazard ratio [HR], 0.79 [95% CI: 0.69, 0.90], P < .001; εa: HR, 0.65 [95% CI: 0.50, 0.83], P < .001; and εe: HR, 0.79 [95% CI: 0.65, 0.95], P = .01). In the nested Cox models, adding LAS to a baseline clinical-volumetric model improved model fit and discrimination, with the χ2 value improving from 36.22 to 54.90 and the concordance index value improving from 0.846 to 0.930 (P < .001 for both). The LAVImin provided complementary prognostic information, with its contribution varying across strain-specific models. Time-dependent ROC analyses demonstrated that LAS identified the development of AF well across prespecified time horizons. Conclusion Cardiac MRI-derived LAS was independently associated with new-onset AF in AHCM and provided incremental prognostic value beyond routine clinical and left atrial volumetric measures. Keywords: Apical Hypertrophic Cardiomyopathy, Atrial Fibrillation, Cardiac MRI, Left Atrial Strain, Heart, Cardiomyopathies, MR Imaging Supplemental material is available for this article. © RSNA, 2026.