Background Implantation of the atrial flow regulator (AFR) to create an interatrial left-to-right shunt has been shown to be safe and feasible to reduce intracardiac filling pressures in patients with heart failure (HF). Objectives We aimed to assess the effect of AFR implantation on 12-month mortality and hospitalization rates in patients with reduced (HFrEF) or preserved HF (HFpEF). Methods One-year follow-up data from 34 subjects enrolled at a single PRELIEVE center were analyzed. The 12-month predicted mortality was calculated using the Meta-Analysis Global Group in Chronic Heart Failure (MAGGIC) risk score. Patients were divided into two groups, according to their history of hospitalizations for HF. Results Study data of 34 patients (HFrEF: 24 [70.6%]; HFpEF: 10 [29.4%]) were assessed. Median follow-up duration was 355 days. In total, 14 (41.2%) patients were hospitalized during the follow-up period and 6 (17.6%) of these patients were hospitalization for HF (HHF). A total of 24 hospitalizations occurred in this period and 8 (33%) hospitalizations were for HHF. The median baseline MAGGIC score was 23 and the median predicted mortality was 13.4/100 patient years. Observed mortality was 3.1/100 patient years. The observed survival (97%) was 10.3% (95% confidence interval 3.6-17.5%, p = 0.004) better than the predicted survival (86.6%). Conclusion Our results suggest that AFR implantation has favorable effects on mortality in patients with heart failure, regardless of ejection fraction. Furthermore, compared to baseline, left ventricular filling pressure (assessed by echocardiography) decreased significantly without right side volume overload at the 1-year follow-up.