Abstract
BACKGROUND: Hypertrophic cardiomyopathy (HCM) involves a substantial risk of atrial arrhythmia, with atrial premature beats (APBs)-a known precursor to atrial fibrillation (AF)-often signaling early atrial dysfunction. However, sensitive assessment of left atrial (LA) function in patients with HCM remains underoptimized. This study aimed to evaluate LA function in patients with HCM via cardiovascular magnetic resonance myocardial tissue tracking (CMR-TT) and to determine the associations between LA-related indices and APB. METHODS: A total of 50 patients with obstructive HCM (HOCM), 54 patients with nonobstructive HCM (NOHCM), and 28 healthy controls were included in the study. CMR-TT was used to quantify LA functional parameters (including strain, strain rate, volume, and emptying fraction). Moreover, 24-hour Holter monitoring was applied to document the occurrence and calculate the frequency of APB. The primary analysis evaluated the association between LA strain and APB occurrence/frequency via logistic regression and correlation analyses, with adjustments made for potential confounders. The inter- and intraobserver reproducibility of LA strain measurements were assessed with intraclass correlation coefficients (ICCs). RESULTS: LA function was decreased in patients with HCM as compared to controls. The patients with HOCM, as compared to those with NOHCM, had a significantly lower LA strain [total strain (εs): 17.7%±6.0%; passive strain (εe): 8.6%±4.3%; active strain (εa): 9.1%±3.7%] and strain rate [peak positive strain rate (SRs): 0.86±0.3 s(-1); peak early negative strain rate (SRe): -0.75±0.2 s(-1); peak late negative strain rate (SRa): -0.82±0.3 s(-1); all P values <0.05], higher LA volume [maximum of LA volume (LAV(max)): 100.7±26.2 mL/m(2); minimum of LA volume (LAV(min)): 49.7±18.8 mL/m(2); volume before LA contraction (LAV(pre)): 80.3±22.1 mL/m(2); all P values <0.05], and lower LA emptying fraction [LAEF; total LAEF (LATEF): 51.3%±10.4%; passive LAEF (LAPEF): 20.3%±6.9%; both P values <0.05]. Multivariate models confirmed an independent association between εs and APB frequency (odds ratio =0.85; P<0.01). The optimal cutoff value for εs in the diagnosis of APB was 20.05%, with a sensitivity of 80.3% and a specificity of 72.7%. CONCLUSIONS: CMR-TT is a promising approach for detecting atrial performance and physiology by quantitatively assessing LA deformation. Moreover, our findings demonstrate a clear association between lower LA εs and the occurrence of APB in patients with HCM. These results suggest that εs may serve as a potential indicator for reflecting atrial electrical instability in HCM and provide preliminary insights for further exploration of its role in clinical decision-making related to arrhythmia management in this patient population.