Elsevier

Heart Rhythm

Volume 18, Issue 8, August 2021, Pages 1416-1422
Heart Rhythm

Experimental
Flecainide-induced QRS complex widening correlates with negative inotropy

https://doi.org/10.1016/j.hrthm.2021.04.007Get rights and content
Under a Creative Commons license
open access

Background

The negative inotropic effect of Class IC antiarrhythmic drugs limits their use for acute cardioversion of atrial fibrillation (AF).

Objective

The purpose of this study was to examine, in an intact porcine model, the effects of pulmonary and intravenous (IV) administration of flecainide on left ventricular (LV) contractility and QRS complex width at doses that are effective in converting new-onset AF to sinus rhythm.

Methods

Flecainide (1.5 mg/kg bolus) was delivered by intratracheal administration and compared to 2.0 mg/kg 10-minute IV administration (European Society of Cardiology guideline) and to 0.5 and 1.0 mg/kg 2-minute IV doses in 40 closed-chest, anesthetized Yorkshire pigs. Catheters were fluoroscopically positioned in the LV to monitor QRS complex width and contractility and at the bifurcation of the main bronchi to deliver intratracheal flecainide.

Results

Peak flecainide plasma concentrations (Cmax) were similar, but the 30-minute area under the curve (AUC) of plasma levels was 1.4- to 2.8-fold greater for 2.0 mg/kg 10-minute IV infusion than for the lower, more rapidly delivered intratracheal and IV doses. AUC for LV contractility (ie, negative inotropic burden) was 2.2- to 3.6-fold greater for 2.0 mg/kg 10-minute IV dose than for the lower, more rapidly delivered doses. QRS complex widening by flecainide was highly correlated with the decrease in LV contractility (r2 = 0.890, P <.0001, for all IV doses; r2 = 0.812, P = .01, for intratracheal flecainide).

Conclusion

QRS complex widening in response to flecainide is strongly correlated with decrease in LV contractility. Rapid pulmonary or IV flecainide delivery reduces the negative inotropic burden while quickly achieving Cmax levels associated with conversion of AF.

Keywords

Atrial fibrillation
Flecainide
Left ventricular contractility
Negative inotropy
Pulmonary drug delivery
QRS complex width

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Funding sources: This study was funded by a grant from InCarda Therapeutics, Inc., to Beth Israel Deaconess Medical Center.

Disclosures: Dr Belardinelli is employed by InCarda Therapeutics, Inc. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.