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Dofetilide discontinuation rates higher in real-world setting vs. clinical trials
Nearly 20% of patients with atrial fibrillation who were hospitalized to start dofetilide had to discontinue the drug before discharge because of QT prolongation or ventricular tachycardia.
According to the study background, patients with AF must be hospitalized when they begin a dofetilide regimen for telemetry and ECG monitoring due to risks for QT prolongation and ventricular tachycardia (VT) associated with the drug. In clinical trials, less than 3% of patients assigned dofetilide discontinued the drug due to QT prolongation or VT, according to the researchers.
The researchers conducted a retrospective analysis of 114 patients with AF who were hospitalized at the Minneapolis Veterans Affairs Health Care System between 2011 and 2014 for starting dofetilide. Patients were given 500 µg dofetilide twice daily if the glomerular filtration rate (GFR) was greater than 60 mL/min, 250 µg twice daily if GFR was 40 mL/min to 60 mL/min or 125 µg twice daily if GFR was 20 mL/min to 40 mL/min. Dosage was reduced when corrected QT was prolonged by more than 15% from baseline or when a patient developed VT.
Dofetilide was discontinued in 22 (19%) patients during the index hospitalization due to QT prolongation (n = 20) or VT (n = 2). In addition, more patients who had to discontinue the drug also were taking other QT-prolonging drugs (45% vs. 24%; P = .04) Odds of dofetilide discontinuation were nearly twice as high in patients taking other QT-prolonging drugs compared with patients who were not taking other QT-prolonging medications (OR = 1.9; P = .04). Fifteen deaths were reported at the end of nearly 4 years of follow-up. Five deaths occurred in patients who discontinued dofetilide, and 10 occurred in patients who continued the drug after discharge.
“These results suggest that the incidence of discontinuation of dofetilide due to adverse events is much higher in a real-world setting than it was reported in clinical trials,” the researchers wrote. – by Tracey Romero
Disclosure: The researchers report no relevant financial disclosures.