Abstract Background Remote monitoring of patients suffering from heart failure (HF) did not result in improved clinical outcomes in the OptiLink-HF trial. However, initiation of medical intervention after transmission of telemedicine alerts triggered by fluid index threshold crossings (FTCs) was low. The relation between weekday of transmission of FTC and subsequent patient contact is unknown. Methods Patients enrolled in the intervention arm of the OptiLink HF trial (n=505, age 66.1±10.1, male 77.2, EF 26.7±6.1%) were analyzed according to the weekday of transmission of FTC. Transmissions of FTC on Mondays to Thursdays were categorized as TD1, Fridays to Sundays as well as bank holidays as TD2. Primary endpoint was time between transmission and telephone contact; secondary endpoints were subsequent medical intervention and hospitalizations. Results During a follow-up of 18 months, 1364 FTC (866 (63.5%) categorized to TD1, 498 (36.5%) to TD2) alerts occurred in 356 patients. In 46.2% of FTC same day telephone contact was performed in group TD1 compared to 18.3% in group TD2 (p<0.001). Accordingly, the median time to contact was significantly longer in TD2 compared to TD1 (2 (1–3) vs. 0 (0–1); p<0.001). Rates of no telephone contact were not different between the groups (12.1% vs. 12.4%; p=0.866). Although, signs of worsening HF were prevalent in 32.4% in TD1 vs. 32.1% in TD2 (p=0.996), initiation of a pharmacological intervention was more likely in TD1 compared to TD2 (27.9% vs. 22.9%; p=0.041). No differences existed concerning hospitalization for HF within 30 days after FTC (3.9% vs. 3.4%; p=0.636). Conclusion Transmission of FTC alerts during weekends and on bank holidays were less likely associated with timely patient contacts and initiation of pharmacological intervention than during the week. Telemedical centers providing 24/7 remote monitoring service might help to optimize patient care. Funding Acknowledgement Type of funding source: None