Makindo Medical Notes

⚠️ Specialist use only: Flecainide should be initiated and monitored by a cardiologist. It must always be co-administered with an AV nodal blocking agent (e.g. β-blocker, diltiazem) to prevent paradoxical 1:1 atrial flutter conduction.

📖 About

• Class Ic antiarrhythmic: potent sodium channel blocker.
• CAST trial (1989, NEJM): Use in post-MI patients with LV dysfunction increased arrhythmic death. Now contraindicated in structural heart disease and IHD.
• Reserved for patients with structurally normal hearts under specialist care.

⚙️ Mode of Action

• Blocks fast inward sodium channels → marked slowing of conduction through atria, AV node, His–Purkinje, and ventricles.
• Widened PR, QRS, and (modestly) QT intervals on ECG.
• Minimal effect on action potential duration compared with Class Ia drugs.
• Negative inotropic effect (caution in impaired LV function).

🩺 Indications

• Paroxysmal atrial fibrillation or atrial flutter (in absence of structural heart disease).
• AV re-entrant tachycardia (e.g. Wolff–Parkinson–White syndrome).
• Other supraventricular tachycardias (SVT) refractory to standard therapy.
• Occasionally used in certain ventricular arrhythmias, only under specialist supervision.

💊 Dosing – Flecainide Acetate (BNF – check locally)

🚫 Contraindications

• Structural heart disease (LV dysfunction, IHD, significant LV hypertrophy).
• Atrial flutter without AV nodal blocker (risk of 1:1 conduction and fast ventricular response).
• Second-/third-degree AV block or sinus node dysfunction (without pacing).
• Cardiogenic shock, severe bradycardia.
• Concomitant use with other Class I antiarrhythmics.

❗ Side Effects

• Dizziness, visual disturbance, metallic taste.
• Palpitations, chest pain, dyspnoea.
• Proarrhythmia: ventricular tachycardia, ventricular fibrillation, sudden death (esp. in structural heart disease).
• Negative inotropy: may precipitate or worsen heart failure.
• Ataxia, tremor, confusion (rare).

🔎 Cautions & Monitoring

• Baseline ECG and echocardiogram required before initiation.
• Serial ECGs to monitor QRS widening (stop if >25% increase from baseline).
• Caution in pacemaker/ICD patients (can alter sensing and capture thresholds).
• Adjust dose in renal or hepatic impairment.

📚 References

• BNF: Flecainide
• Summary of Product Characteristics
• CAST Trial, NEJM 1989: Mortality with Class Ic post-MI