Class 1C antiarrhythmic agents are effective for treating atrial tachyarrhythmias, but their use is restricted in patients with coronary artery disease (CAD). Data on the safety of the use of 1C agents in patients with CAD in the absence of recent acute coronary syndromes are lacking.

This study sought to evaluate the safety and feasibility of treatment with 1C agents in patients with varying degrees of CAD in a large serial, real-world cohort.

We retrospectively identified all patients at our institution from January 2005 to February 2021 on a 1C agent (n = 3,445) and those on sotalol or dofetilide (n = 2,216) as controls, excluding those with a prior history of ventricular tachycardia, implantable cardioverter-defibrillator placement, or nonrevascularized myocardial infarction. Baseline clinical characteristics included degree of CAD (categorized as none, nonobstructive, or obstructive), other comorbid illness, and medication use. Clinical outcomes, including survival, were ascertained. We performed Cox regression analysis to evaluate the effect of 1C use on event-free survival across varying degrees of CAD.

After adjustment for baseline characteristics, there was an independent association between 1C use and improved mortality. However, there was an interaction between 1C use and degree of CAD (compared to sotalol) demonstrating poorer event-free survival among those with obstructive coronary disease (HR: 3.80; 95% CI: 1.67-8.67; P = 0.002).

Among select patients with nonobstructive CAD and without a history of ventricular tachycardia, 1C agents are not associated with increased mortality. Therefore, these agents may be an option for some patients in whom they are frequently restricted. Further prospective studies are warranted.