The effect of atrial morphology on atrial function in hypertrophic cardiomyopathy

Abstract Background Atrial dysfunction is a relevant marker of disease progression in hypertrophic cardiomyopathy (HCM). Left atrial (LA) longitudinal functional parameters and volumes derived from cardiac magnetic resonance (CMR) are associated with new-onset atrial fibrillation (AF) and its complications. The asymmetrical shape of the LA and its morphological alterations may influence LA function and could provide new mechanistic insights into HCM. Objective To assess the association between CMR derived functional and morphological LA characteristics in HCM patients. Methods Patients with an established diagnosis of HCM were included. HCM patients with a history of AF or without available CMR were excluded. CMR acquisitions used for clinical indication of heart failure diagnosis and etiology were retrospectively analyzed to obtain LA reservoir (LAres), booster (LAboost), and conduit (LAcond) strain on 2-chamber views (Medis Suite v3.2). Strain measurements of the other cardiac chambers were also performed. Manual tracing of LA endocardial border at the LA orthogonal longitudinal and transverse diameters on 2-, 3-, and 4-chamber views was performed (Philips Portal v10.1). Univariable and multivariable forward linear regression was employed to assess associations between functional and morphological LA measures. Results A total of 81 HCM patients were included, mean age 52±16 years, 59 (73%) male, and left ventricular ejection fraction 72.0±8.3%. Mean LAres was 27.2±11.0%, LAboost -14.9%±6.4%, and LAcond -12.5%±7.5%. LA morphological parameters are summarized in Table 1. The strongest correlates in multivariable regression for LAres were longitudinal LA diameter on 2-chamber view (Figure 1) and transverse LA diameter ratio between 4- and 2-chamber view (R2 0.30, p<0.001). The strongest correlates in multivariable regression for LAboost were longitudinal LA diameter on 2- and 4-chamber view, antero-posterior LA diameter on 3-chamber view, and LA area on 4-chamber view (R2 0.29, p<0.001). Longitudinal 2-chamber LA diameter also correlated with LAcond, but the strongest correlates of LAcond in multivariable regression were longitudinal-transversal LA diameter ratio on 2-chamber view, LA area on 3-chamber view, and LA sphericity (R2 0.25, p<0.001). Conclusions CMR-derived LA functions in HCM patients differently correlated with LA morphology. LA longitudinal 2-chamber diameter had a strong influence on all LA functions.Left atrial measures in HCMLA function and diameter correlations