Objective Recent studies have reported suboptimal up-titration of heart failure (HF) therapies in patients with heart failure and a reduced ejection fraction (HFrEF). Here, we report on the achieved doses after nurse-led up-titration, reasons for not achieving the target dose, subsequent changes in left ventricular ejection fraction (LVEF), and mortality. Methods From 2012 to 2018, 378 HFrEF patients with a recent (< 3 months) diagnosis of HF were referred to a specialised HF-nurse led clinic for protocolised up-titration of guideline-directed medical therapy (GDMT). The achieved doses of GDMT at 9 months were recorded, as well as reasons for not achieving the optimal dose in all patients. Echocardiography was performed at baseline and after up-titration in 278 patients. Results Of 345 HFrEF patients with a follow-up visit after 9 months, 69% reached >= 50% of the recommended dose of renin-angiotensin-system (RAS) inhibitors, 73% reached >= 50% of the recommended dose of beta-blockers and 77% reached >= 50% of the recommended dose of mineralocorticoid receptor antagonists. The main reasons for not reaching the target dose were hypotension (RAS inhibitors and beta-blockers), bradycardia (beta-blockers) and renal dysfunction (RAS inhibitors). During a median follow-up of 9 months, mean LVEF increased from 27.6% at baseline to 38.8% at follow-up. Each 5% increase in LVEF was associated with an adjusted hazard ratio of 0.84 (0.75-0.94, p = 0.002) for mortality and 0.85 (0.78-0.94, p = 0.001) for the combined endpoint of mortality and/or HF hospitalisation after a mean follow-up of 3.3 years. Conclusions This study shows that protocolised up-titration in a nurse-led HF clinic leads to high doses of GDMT and improvement of LVEF in patients with new-onset HFrEF.