Abstract Background Aortic stenosis (AS) is a progressive disease, which untreated leads to irreversible myocardial damage and potentially death. Patients with AS may present with acute decompensation (ADAS) even during active surveillance. Purpose In this TAVI-NOR sub-study, we investigate the clinical profile, risk factors, epidemiology and long-term outcomes of patients treated with TAVI after presenting with ADAS compared to stable patients who underwent elective TAVI (no ADAS). Method A total of 600 patients with severe AS consecutively treated with TAVI between January 2012 and July 2019 were enrolled in TAVI-NOR study. Predictors and long-term clinical outcomes were explored in binary logistic and Cox regression models. Results A total of 68 patients (11.3%) received urgent TAVI due to acute hospitalization with ADAS. Age (80±8.0 years vs 81±6.0 years, p=0.662), gender (56% males vs 50% males, p=0.361) and other comorbidities at baseline such as cardiovascular disease, chronic lung disease and atrial fibrillation (AF) were comparable in patients with ADAS and no ADAS (n=532) (p>0.05 for all). However, patients with ADAS had greater symptom burden (NYHA III-IV 81% vs 51%, p<0.001), lower blood pressure, higher heart rate and lower estimated glomeruli filtration rate (52.0±10.8 vs 54.6±9.8 mL/min/1.73m2, p<0.045). They had also higher prevalence of ECG left ventricular (LV) hypertrophy (40% vs 27%, p=0.027), more often reduced LV ejection fraction (<50%) (41% vs 16%, p<0.001), lower stroke volume (39±11 ml/m2 vs 42±11 ml/m2 vs, p=0.030) a trend of abnormal ECG (p=0.055) and longer hospital stay (11.5 ±8.7 days 6.6± 4.9 days, p<0.001). Patients with ADAS were comparable with no ADAS in terms of early short-term (<30 days) all-cause mortality (p>0.05). Although 1-year mortality was comparable (1.5% in ADAS vs 2.1% in no ADAS, p>0.99), mid- to late-term mortality rates were significantly higher in patient with ADAS receiving urgent TAVI, with 3-, 5- and 7 years mortality of 22% vs 11%, p=0.008; 46% vs 29%, p=0.005; 53% vs 39%, p=0.033, respectively. In a Kaplan-Meier analysis, event-free survival was significantly reduced for patients with ADAS undergoing urgent TAVI compared with stable patients undergoing elective TAVI HR 1.63, 95% CI 1.15-2.31, p=0.006), confirmed by a multivariable-adjusted model (HR 1.54; 95% CI 1.05-2.25, p=0.026) independent of age, gender, AF, LV ejection fraction and time from diagnosis to TAVI (Fig). Conclusion Patients with AS presenting with acute decompensation and treated with urgent TAVI had excellent short-term survival. This was irrespective of increased symptom burden, adversely remodeled and functionally reduced LV at baseline. These findings might explain the observed higher mid- and long-term mortality compared with stable patients undergoing elective TAVI. It is essential to identify patients at risk of acute decompensation and treat them timely before irreversible myocardial damage occur.