Cardiac Damage Staging Classification Predicts Prognosis in All the Major Subtypes of Severe Aortic Stenosis: Insights from the National Echo Database Australia

Background: There are currently no established prognostic models for “low-gradient” severe aortic stenosis (AS), including those with low-flow, low-gradient (LFLG) or normal-flow, low-gradient (NFLG) severe AS. The “cardiac damage staging classification” has been validated as a clinically useful prognostic tool for high-gradient severe AS but not yet for these other common subtypes of severe AS, LFLG and NFLG. Methods: The authors analyzed data from the National Echo Database of Australia, a large national, multicenter registry with individual data linkage to mortality. Of 192,060 adults (mean age, 62.8 ± 17.8 years) with comprehensive ultrasound profiling of the native aortic valve studied between 2000 and 2019, 12,013 (6.3%) had severe AS. On the basis of standard echocardiographic parameters, 5,601 patients with high-gradient, 611 with classical and 959 with paradoxical LFLG, and 911 with NFLG severe AS were identified. Mean follow-up was 88 ± 45 months. All-cause and cardiovascular-related mortality were assessed for each group on an adjusted basis (age and sex) and analyzed by cardiac damage stage. Results: Patients with LFLG AS had greater associated cardiac damage at diagnosis (stages 3 and 4 in 34% of those with classical LFLG, 22.5% of those with paradoxical LFLG, 15.5% of those with NFLG, and 14% of those with high-gradient AS; P < .001). For all four major subtypes of severe AS, there was a progressive increase in 1- and 5-year mortality with increasing cardiac damage score. For example, for paradoxical LFLG severe AS, compared with stage 0 patients, adjusted 1-year all-cause mortality was 22% higher in stage 1 patients, 55% higher in stage 2 patients (P = .095), and 155% higher in stage 3 and 4 patients (P < .001). Among patients with classical LFLG severe AS, compared with stage 1 patients, adjusted 1-year all-cause mortality was 55% higher in stage 2 patients (P = .018) and 100% higher in stage 3 and 4 patients (P < .001). Conclusions: Regardless of severe AS subtype, increasing severity denoted by the cardiac damage staging classification is strongly associated with increasing mortality risk.