Enlarged left atrium and sudden death risk in hypertrophic cardiomyopathy patients with or without atrial fibrillation

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BackgroundThe relationships among enlarged left atrial dimension (LAD), the presence or absence of atrial fibrillation (AF), and sudden death risk in patients with hypertrophic cardiomyopathy (HCM) remain unclear. The aim of this study was to evaluate the impact of enlarged LAD on sudden death risk in HCM patients with or without documented AF. MethodsThis study included 564 HCM patients (follow-up period: 10.8±7.4 years). LAD was measured from the parasternal long-axis view as the antero-posterior linear diameter at end-systole. Sudden death was defined as the combined endpoint of sudden cardiac death and potentially lethal arrhythmic events, and log-rank tests and Cox proportional hazards models were applied to evaluate the impact of LAD enlargement on the combined endpoint. ResultsThe proportions of patients with sudden death and potentially lethal arrhythmic events were significantly higher among patients with enlarged LAD (≥48mm, N=86) compared with those without enlarged LAD (19.8% vs. 8.2%; p=0.002). However, enlarged LAD was not identified as an independent determinant of sudden death risk in multivariate analysis of all study HCM patients [adjusted hazard ratio (HR): 1.83; 95% confidence interval (CI): 0.95–3.53; p=0.071]. Among patients without documented AF during the follow-up periods, enlarged LAD was an independent determinant of sudden death risk (adjusted HR: 5.23; 95% CI: 2.17–12.58; p<0.001), although there was no significant difference in sudden death risk between patients with and without enlarged LAD in patients with documented AF (adjusted HR: 0.77; 95% CI: 0.31–1.90; p=0.567). ConclusionsThese results suggest that the relationship between LAD and outcome is influenced by the presence or absence of AF in HCM patients. It may thus be necessary to consider the need to prevent sudden death in LAD-enlarged HCM patients without documented AF.