BackgroundHeart failure (HF) is a progressive disease associated with a high burden of symptoms, high morbidity and mortality, and low quality of life (QoL). This study aimed to evaluate the feasibility and potential outcomes of a novel multicomponent complex intervention, to inform a future full-scale randomized controlled trial (RCT) in Switzerland.MethodsWe conducted a pilot RCT at a secondary care hospital for people with HF hospitalized due to decompensated HF or with a history of HF decompensation over the past 6 months. We randomized 1:1; usual care for the control (CG) and intervention group (IG) who received the intervention as well as usual care. Feasibility measures included patient recruitment rate, study nurse time, study attrition, the number and duration of consultations, intervention acceptability and intervention fidelity. Patient-reported outcomes included HF-specific self-care and HF-related health status (KCCQ-12) at 3 months follow-up. Clinical outcomes were all-cause mortality, hospitalization and days spent in hospital.ResultsWe recruited 60 persons with HF (age mean = 75.7 years, ± 8.9) over a 62-week period, requiring 1011 h of study nurse time. Recruitment rate was 46.15%; study attrition rate was 31.7%. Follow-up included 2.14 (mean, ± 0.97) visits per patient lasting a total of 166.96 min (mean, ± 72.55), and 3.1 (mean, ± 1.7) additional telephone contacts. Intervention acceptability was high. Mean intervention fidelity was 0.71. We found a 20-point difference in mean self-care management change from baseline to 3 months in favour of the IG (Cohens’d= 0.59). Small effect sizes for KCCQ-12 variables; less IG participants worsened in health status compared to CG participants. Five deaths occurred (IG = 3, CG = 2). There were 13 (IG) and 18 (CG) all-cause hospital admissions; participants spent 8.90 (median, IQR = 9.70, IG) and 15.38 (median, IQR = 18.41, CG) days in hospital. A subsequent full-scale effectiveness trial would require 304 (for a mono-centric trial) and 751 participants (for a ten-centre trial) for HF-related QoL (effect size = 0.3; power = 0.80, alpha = 0.05).ConclusionWe found the intervention, research methods and outcomes were feasible and acceptable. We propose increasing intervention fidelity strategies for a full-scale trial.Trial registrationISRCTN10151805, retrospectively registered 04/10/2019.Supplementary InformationThe online version contains supplementary material available at 10.1186/s40814-023-01338-7.