Effective anticoagulation in patients undergoing electrical cardioversion (ECV) for symptomatic atrial fibrillation is important to prevent adverse events. High medication adherence is a requirement. In patients with newly diagnosed atrial fibrillation (n = 169) who were intended to undergo ECV, the aim of this study was to measure self-reported short- and long-term adherence, evaluate whether dabigatran plasma concentrations reflect adherence, measure treatment satisfaction and assess whether adherence and treatment satisfaction are correlated.
Plasma concentrations (liquid-chromatography tandem mass spectrometry), the 8-point Morisky Medication Adherence Scale (MMAS-8) and the Anti-Clot Treatment Scale (ACTS) were measured after 3 and 7 weeks of treatment. Combined mean peak (1-3 hours after intake) and trough (10-16 hours after intake) plasma concentrations were 175 (SD 109) ng/mL and 75 (SD 45) ng/mL, respectively. There was no relationship between short-term adherence (last 3 days) or long-term adherence (last 3-4 weeks) and plasma concentrations, unless the last intake was more than 48 hours ago. After 7 weeks high, moderate and low adherence, according to the MMAS-8, was seen in 74%, 21% and 5% of patients, respectively. Treatment satisfaction was high (median ACTS score 68.5, range 46-75 points). Treatment satisfaction and adherence were not correlated.
The percentage of patients in the high adherence group (74%) was lower than expected, which is a matter of concern. Dabigatran plasma concentrations could not detect short- or long-term non-adherence, unless the drug was last taken more than 48 hours ago. Treatment satisfaction did not correlate with adherence.