Left atrial functional impairment as a predictor of atrial fibrillation: insights from cardiac CT.

OBJECTIVES

A strong association exists between left atrial (LA) structural remodeling and the development of atrial fibrillation (AF). The role of LA function in AF prediction remains unclear. We studied the relationship between LA function and incident AF using cardiac CT.

MATERIALS AND METHODS

We retrospectively analyzed patients who underwent multiphasic cardiac CT. LA volumes and parameters of LA global, reservoir and booster function were calculated. The association between measures of LA function and incident AF was analyzed using multivariable Cox regression adjusting for clinical variables, LA volume and left ventricular function.

RESULTS

1025 patients (age 64 years ± 14) were evaluated. Over a median of 3.9 years, 90 patients developed AF. There was a significant association between LA total emptying fraction (adjusted hazard ratio (HR) 1.05; 95% CI: 1.02-1.05 per 1% decrease, p < 0.001), LA reservoir function (HR 1.04; 95% CI: 1.02-1.06 per 1 mL/m decrease in LA expansion index, p < 0.001) and passive LA emptying (HR 1.08; 95% CI: 1.03-1.13 per 1% decrease in LA passive emptying fraction, p < 0.001) with incident AF, but no association with LA booster function. Incorporating LA function into predictive models improved risk stratification beyond clinical variables and LA volume. Mediation analysis demonstrated that 46% of the effect of LA volume on AF was mediated via LA dysfunction.

CONCLUSION

LA functional impairment is common even in patients with normal LA volume and provides additional prognostic information for AF risk. The findings underscore the significance of LA mechanical dysfunction in the pathogenesis of AF.

KEY POINTS

Question A strong association exists between left atrial structural remodeling and incident atrial fibrillation. The role of left atrial function in atrial fibrillation prediction remains unclear. Findings Left atrial reservoir and passive emptying function (but not booster function) predict incident atrial fibrillation independent of left atrial volume and clinical risk factors. Clinical relevance Left atrial functional impairment precedes the development of atrial fibrillation. Measures of left atrial reservoir and passive emptying function are independent predictors of incident atrial fibrillation.