Prescription of drugs with potential adverse effects on cardiac conduction in Parkinson's disease

Background: Epidemiological studies report an association of ventricular arrhythmias with medication through prolongation of the cardiac QT interval. This has implications in the management of Parkinson's disease, as commonly prescribed drugs for non-motor symptoms and comorbidities have QT prolonging potential.

Objectives: To review prescribed medication in Parkinson's disease patients, in particular the use of drugs that may prolong the cardiac QT interval, in relation to other risk factors for QT prolongation.

Methods: Medication prescription and doses, presence of underlying cardiac disease, patient age, and sex were recorded in a cross-sectional sample of 360 current PD patients attending two district and one regional specialist hospital-based movement disorder clinics.

Results: We sampled 360 consecutive patients with PD, median age 66.5 years (interquartile range 58.5-74.8) and median disease duration 4.2 years (interquartile range 1.2-8.0 years). 125 (34.7%) were taking one or more drugs with definite potential to prolong QT, including domperidone in 91 (25.2%), citalopram or escitalopram in 47 (13.1%), and concurrent antibiotics in 5 (1.3%). Cofactors increasing the risk for QT interval prolongation were: age over 60 years 71.7%, female sex 46.9%, and presence of cardiac disease 19.2%. In patients with combined risk factors, the rate of prescription of at least one definite QT prolonging drug was between 34.5 and 42.1%.

Conclusions: Combination therapy and comorbidity relevant to cardiac QT prolongation are common in patients with Parkinson's disease. Strategies to reduce the proportion of patients at risk from iatrogenic adverse cardiac events are warranted.