Dofetilide Initiation and Implications of Deviation From the Standard Protocol – A Real World Experience

Background: Manufacturer/federal drug administration (FDA) recommends inpatient initiation of dofetilide with the manufacturer providing an initiation algorithm. The outcomes of algorithm deviation have not been reported outside of clinical trials. Objective: We sought to perform a chart review of all the patients admitted for inpatient initiation of dofetilide to report on the incidence of protocol deviations and their implications. Methods: We performed a retrospective review of all patients over a 15-month periodwho were initiated on dofetilide for the very first time or reinitiated on dofetilide after a break of three months or more at our institution. We assessed data about patients who were given dofetilide without adherence to the protocol (i.e. protocol deviation). Results: A total of 189 patients were included in the study with a median age of 66 ± 9 years. Mean baseline QTc interval was 436 ± 32 msec, and 61% (116/189) were in atrial fibrillation (AF) at the time of dofetilide initiation. In 9% (17/189) of patients, the drug was discontinued due to intolerance or inefficacy. Therapy in 49% (93/189) of patients was noted to deviate from manufacturer recommended protocol with deviations more than once in some patients during the same hospitalization. Baseline QTc exceeding 440 msec(>500msec in conduction abnormalities) was the most frequent deviation (25%; 47/189).Ventricular tachyarrhythmia occurred in 4% (7/189) of patients, did not differ between patients, and occurred with and without protocol deviations (5% vs 2%; p = 0.27). Conclusions: In our retrospective study, there were frequent deviations from the manufacturer-recommended algorithm guidelines for dofetilideinitation, primarily due to prolonged baseline QTc interval. The impact of these protocol deviations on drug discontinuation was uncertain; however, significant adverse events were higher in the deviation group compared to the group that fully adhered to the protocol. Further multicenter studies are warranted to clarify our findings.