Initial experience with antiarrhythmic medication monitoring by clinical pharmacists in an outpatient setting: a retrospective review.

BACKGROUND: Antiarrhythmic medications may be used chronically to prevent recurrences of cardiac arrhythmias. Vaughan Williams class I and class III antiarrhythmic drugs have the potential for serious adverse effects, some of which can result in significant morbidity or mortality. To provide early detection and prevention of adverse events, appropriate therapeutic monitoring has been suggested during amiodarone therapy.
OBJECTIVE: The objective of this study was to monitor antiarrhythmic drug therapy to improve the continuity and consistency of care for patients receiving class I or class III antiarrhythmic drugs.
METHODS: Patients receiving antiarrhythmic medications, including amiodarone, sotalol, dofetilide, and propafenone, were referred to an antiarrhythmic medications clinic (at an academic university), Columbus, Ohio, either at the time of hospital discharge or during an outpatient appointment with a cardiologist, for monitoring. A retrospective chart review was conducted in consecutive outpatients attending the clinic between July 2007 and April 2008. Antiarrhythmic medication monitoring protocols were developed for a pharmacy-based outpatient clinic by a collaborative effort between pharmacists, physicians, and nurses. Adherence to monitoring protocols was assessed, and the type and frequency of pharmacist-identified events and interventions were determined. Continuum of care for patients was facilitated by coordination of referral to specialty clinics (n = 11) or pharmacist contact with physicians (n = 40).
RESULTS: In all, 134 patients were included and were receiving amiodarone (n = 58), sotalol (n = 40), dofetilide (n = 28), or propafenone (n = 8). At enrollment, 59.0% of patients had completed all recommended laboratory and objective testing compared with 98.5% after the initial visit. Adherence to monitoring protocols was improved in patients receiving amiodarone, dofetilide, or propafenone, but not sotalol. Fifty-four patients had a return visit, and after follow-up visits, 100% of patients were current with testing. Pharmacist-identified events or interventions occurred during 38% of visits, including unrecognized adverse event detection (ie, pulmonary function decline, QT prolongation, laboratory abnormality) and clinically significant drug interaction identification. Amiodarone was associated with the highest rate of detected adverse events (23% of patient visits). A change in the antiarrhythmic medication regimen was recommended for 9 patients that later resulted in the discontinuation of therapy in 3 patients.
CONCLUSION: Pharmacist monitoring of outpatient antiarrhythmic medication therapy appeared to improve patient adherence to recommended testing protocols and to help identify adverse events and clinically significant drug interactions.