Several cardiac and non-cardiac drugs are known to prolong the QT interval, an important phase in the electrical heart cycle. Patients who use these drugs have an increased risk to develop arrhythmias (Torsade de Pointes), which can result in sudden cardiac death. In psychiatry, the use of (combinations of) QT prolonging drugs is common practice. Most data on drug-associated QT prolongation are derived from clinical trials with healthy volunteers or from case reports. Studies conducted in clinical practice are rare. Physicians are left with questions on the relevance of QT-prolongation and on how to deal with this risk. This project consists of different parts, with specific objectives. Pharmaco-epidemiological studies will deliver data on the prevalence of the use of (combinations of) QT prolonging drugs in clinical practice. Research into medication management will document how physicians and pharmacists currently deal with drug interactions and the risk of QT prolongation. Clinical studies in psychiatric institutions and in UZ Leuven will further demonstrate the QT prolonging effect of the addition of a QT prolonging drug to established medication profiles. Finally, algorithms to support health care professionals in the management of QT prolonging drugs will be developed and validated, and possibilities for integration of these algorithms in electronic decision support systems will be investigated.