The coronavirus disease 2019 (COVID-19) pandemic is an unprecedented challenge. Meeting this has resulted in changes to working practices and the impact on the management of patients with heart failure with reduced ejection fraction (HFrEF) is largely unknown. We performed a retrospective, observational study contrasting patients diagnosed with HFrEF attending specialist heart failure clinics at a UK hospital, whose subsequent period of optimisation of medical therapy was during the COVID-19 pandemic, with patients diagnosed the previous year. The primary outcome was the change in equivalent dosing of ramipril and bisoprolol at 6-months. Secondary outcomes were the number and type of follow-up consultations, hospitalisation for heart failure and all-cause mortality. In total, 60 patients were diagnosed with HFrEF between 1 December 2019 and 30 April 2020, compared to 54 during the same period of the previous year. The absolute number of consultations was higher (390 vs 270; p = 0.69), driven by increases in telephone consultations, with a reduction in appointments with hospital nurse specialists. After 6-months, we observed lower equivalent dosing of ramipril (3.1 \pm 3.0 mg vs 4.4 \pm 0.5 mg; p = 0.035) and similar dosing of bisoprolol (4.1 \pm 0.5 mg vs 4.9 \pm 0.5 mg; p = 0.27), which persisted for ramipril (mean difference 1.0 mg, 95% CI 0.018–2.09; p = 0.046) and bisoprolol (mean difference 0.52 mg, 95% CI -0.23–1.28; p = 0.17) after adjustment for baseline dosing. We observed no differences in the proportion of patients who died (5.0% vs 7.4%; p = 0.59) or were hospitalised with heart failure (13.3% vs 9.3%; p = 0.49). Our study suggests the transition to telephone appointments and re-deployment of heart failure nurse specialists was associated with less successful optimisation of medical therapy, especially renin-angiotensin inhibitors, compared with usual care.