Utility of Functional and Volumetric Left Atrial Parameters Derived From Preprocedural Cardiac CTA in Predicting Mortality After Transcatheter Aortic Valve Replacement

Abstract

BACKGROUND. Cardiac CTA is required for preprocedural workup before transcatheter aortic valve replacement (TAVR) and can be used to assess functional parameters of the left atrium (LA). OBJECTIVE. We aimed to evaluate the utility of functional and volumetric LA parameters derived from cardiac CTA to predict mortality in patients with severe aortic stenosis (AS) undergoing TAVR. METHODS. This retrospective study included 175 patients with severe AS (92 men, 83 women; median age, 79.0 years) who underwent cardiac CTA for clinical pre-TAVR assessment. A postdoctoral research fellow calculated maximum and minimum LA volumes using biplane area-length measurements; these values were indexed to body surface area, and maximum and minimum LA volume index (LAVI_max and LAVI_min, respectively) values were calculated. The LA emptying fraction (LAEF) was automatically calculated. All-cause mortality within a 24-month follow-up period after TAVR was recorded. To identify parameters predictive of mortality, Cox regression analysis was performed, and results were summarized by hazard ratio (HR) and 95% CI. The Harrell C-index was used to assess model performance. A radiology resident repeated the measurements in a random sample of 20% (n = 35) of the cases, and interobserver agreement was computed using the intraclass correlation coefficient (ICC). RESULTS. Thirty-eight deaths (21.7%) were recorded within a median follow-up of 21 months. LAVI_max (HR, 1.02 [95% CI, 1.01-1.04]; p = .01), LAVI_min (HR, 1.02 [95% CI, 1.01-1.04]; p < .001), and LAEF (HR, 0.97 [95% CI, 0.95-0.99]; p = .002) were predictive of mortality in univariable analysis. After adjusting for clinical parameters, only LAEF (HR, 0.97 [95% CI, 0.94-0.99]; p = .02) independently predicted mortality. The C-index of the Society of Thoracic Surgeons Predicted Risk of Mortality (STS-PROM) significantly increased from 0.636 to 0.683, 0.694, and 0.700 when incorporating into the model LAVI_max, LAVI_min, and LAEF, respectively. The ICC for maximum and minimum LA volumes and LAEF ranged from 0.94 to 0.99. CONCLUSION. LAEF derived from preprocedural cardiac CTA independently predicts mortality in patients with severe AS undergoing TAVR. CLINICAL IMPACT. Cardiac CTA-derived LA function, evaluated during pre-TAVR workup, can be used to assess preprocedural risk and may improve risk stratification in post-TAVR surveillance.

Keywords: TAVR; all-cause mortality; aortic valve stenosis; cardiac CT; left atrium function; left atrium volume; transcatheter aortic valve replacement.