Abstract Body: Background:
The management of patients with combined aortic stenosis (AS) and hypertrophic cardiomyopathy (HCM) is tricky. HCM causes a dynamic obstruction, while AS causes a fixed obstruction, both causing a hindrance to left ventricular output. We aim to study the outcomes of hospitalizations with co-prevalent HCM and AS.

Methods:
We queried the National Inpatient Sample 2018-2020 for adult hospitalizations with AS. This sample was stratified based on the prevalence of HCM. Mortality, arrhythmia prevalence, and acute cardiac complications were compared in aortic stenosis hospitalizations with and without
AS. A multivariate regression analysis was performed to study the impact of HCM on mortality, arrhythmias, and other complications in patients with AS.

Results:
In hospitalizations with aortic stenosis (n=2483854), a total of 11820 had underlying HCM (0.47%). The mean age was 76 years and 64% were females. Hospitalizations with AS and HCM as compared to those without HCM had a higher prevalence of arrhythmias including first
degree AV block, atrial flutter, atrial fibrillation, ventricular tachycardia and ventricular fibrillation (Table 1). The occurence of cardiogenic shock was also higher in this subgroup. The difference in mortality, acute coronary syndrome, acute heart failure and cardiac arrest was not statistically significant in AS hospitalizations with and without HCM (Table 1). Multivariate regression analysis revealed a higher odds of arrhythmias (OR-1.44; C.I: 1.36-1.62; P<0.001) and cardiogenic shock (OR-1.58; C.I: 1.22-2.06; P<0.001) with HCM in AS hospitalizations.

Conclusion:
Prior studies have demonstrated worse outcomes in AS patients with pre-existing HCM, especially post TAVI. Our study concludes that HCM was associated with a higher odds of arrhythmias and cardiogenic shock in AS hospitalizations.