Flecainide-induced QRS complex widening correlates with negative inotropy.
Ana B Rabêlo Evangelista1, Felipe R Monteiro1, Bruce D Nearing2
1Department of Medicine, Beth Israel Deaconess Medical Center, Boston Massachusetts; Faculdade de Medicina da Universidade de Sao Paulo, Sao Paulo, Brazil.
Heart Rhythm
|April 13, 2021
Summary
Rapid administration of flecainide (a Class IC antiarrhythmic drug) via pulmonary or IV routes reduces negative inotropic effects. This method achieves effective atrial fibrillation (AF) conversion with less impact on left ventricular contractility.
Area of Science:
- Cardiology
- Pharmacology
- Pulmonary Medicine
Background:
- Class IC antiarrhythmic drugs, like flecainide, can cause negative inotropic effects, limiting their use in acute cardioversion of atrial fibrillation (AF).
- Understanding the impact of different administration routes and speeds on flecainide's cardiac effects is crucial for optimizing AF treatment.
Purpose of the Study:
- To investigate the effects of pulmonary and intravenous (IV) flecainide administration on left ventricular (LV) contractility and QRS complex duration.
- To compare these effects at doses effective for converting new-onset AF to sinus rhythm in a porcine model.
Main Methods:
- Flecainide was administered intratracheally (1.5 mg/kg bolus) and intravenously (2.0 mg/kg over 10 min, or 0.5-1.0 mg/kg over 2 min) in anesthetized pigs.
- Left ventricular (LV) contractility and QRS complex width were monitored using catheters positioned in the LV.
Main Results:
- While peak flecainide concentrations (Cmax) were similar, the 30-minute area under the curve (AUC) was higher with the slower IV infusion.
- The negative inotropic burden (AUC for LV contractility) was significantly greater with the 2.0 mg/kg 10-minute IV dose.
- QRS complex widening strongly correlated with decreased LV contractility across all administration methods.
Conclusions:
- Rapid pulmonary or IV flecainide delivery minimizes the negative inotropic burden associated with AF cardioversion.
- Faster administration achieves therapeutic Cmax levels more quickly, potentially improving the safety profile for acute AF treatment.
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