Initiation and outcomes with Class Ic antiarrhythmic drug therapy

Area of Science:

• Cardiology
• Electrophysiology
• Pharmacology

Background:

• Expert recommendations advise exercise testing during Class Ic antiarrhythmic initiation.
• Class Ic agents are used for atrial arrhythmias.

Purpose of the Study:

• Evaluate discontinuation rates and reasons for Class Ic agents within one year.
• Assess proarrhythmia incidence and the role of treadmill testing.
• Determine the value of routine exercise testing post-initiation.

Main Methods:

• Retrospective cohort study of 300 patients initiated on Class Ic agents (flecainide or propafenone) from 2011-2016.
• Data collected via chart review and pharmacy database.
• Inclusion criteria: patients with atrial arrhythmias.

Main Results:

• One proarrhythmic event (0.3%) occurred during drug initiation.
• Treadmill testing led to discontinuation in 5.3% of patients due to proarrhythmia or ischemia.
• Exercise testing significantly influenced the decision to discontinue Class Ic drugs (p < 0.0001).
• Lack of efficacy was the primary reason for discontinuation during follow-up (32%).

Conclusions:

• Class Ic agent initiation is associated with a low proarrhythmia rate when proper screening is performed.
• Treadmill testing provides incremental value and should be routinely performed after initiating Class Ic antiarrhythmics.