The intervention consists of the use of an electronic Medication Adherence Monitor for a 6-month period as well as 2 visits to the heart failure outpatient clinic of the TweeSteden hospital (usual care). This monitor (a) dispenses all prescribed medication in the right dosage at the specified time, (b) reminds patients to take their medications through an alarm, sms or voicemail service and records adherence, and (c) sends critical data about non-adherence to the heart failure nurse, via a web application (CarebyWeb). The Medication Adherence Monitor is provided to the patient by the hospital pharmacy, including an instruction how to use the device. After the intervention patients return to usual care only. We expect a training effect, with continued improved adherence in the intervention group.

Objective medication adherence will be assessed using the MASS monitor output collected in a web-based application and the refill rates provided by the patients' pharmacies.

A cost-benefit analysis will be assessed by means of the TiC-P questionnaire and event rate (and related DBC (diagnosis treatment combination, the Dutch system to allocate costs to treatments of specific patient groups)). The TiC-P questionnaire will enable us to compare healthcare consumption in the intervention and control group.

Clinical characteristics (e.g. NYHA function class determination, LVEF, exercise capacity, blood tests) and self-reported HF symptoms