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Clinical and electrophysiologic effects of flecainide in patients with refractory ventricular tachycardia
E V Capparelli1, J Kluger, J C Regnier
1Department of Pharmacy, Hartford Hospital, Connecticut 06115.
Abstract:
The electrophysiologic effects and antiarrhythmic efficacy of flecainide were evaluated by electrophysiologic study (EPS) in 20 patients with ventricular tachycardia (VT) refractory to an average 2.9 drugs. In 19 patients EPSs were performed with patients not receiving antiarrhythmic medications and receiving oral flecainide therapy at steady state (mean dose, 235 +/- 67 mg/day). Flecainide significantly increased the QRS complex duration (27%, P less than .001), PR interval (17%, P less than .001), and right ventricular effective refractory periods 8.5% and 21.1% (P less than .01) for the first and second extrastimuli, respectively. During baseline EPS, 17 patients were induced into VT and two were noninducible. Flecainide prevented EPS-induced VT in five patients and the induced VT became slow and hemodynamically stable in three. Two patients who failed flecainide monotherapy were induced into slow hemodynamically stable VT with flecainide in combination with amiodarone. The two noninducible patients, during baseline EPS, had suppression of spontaneous VT with flecainide. Overall, 13 of 20 patients received flecainide either alone or in combination with amiodarone for chronic therapy. Side effects encountered during the study consisted of blurred vision, dizziness, weakness, lethargy, nausea, worsened heart failure and bradyarrhythmias. After a mean 9-month follow-up (3 to 16 months) nine patients remain on flecainide therapy. There were three recurrences of slow, hemodynamically stable VT and no episodes of sudden death. Low-dose flecainide, either alone or in combination with other agents, is effective therapy for certain patients with refractory VT but heart failure remains a significant concern in patients with depressed left ventricular function.
Insights
Flecainide effectively treated drug-resistant ventricular tachycardia (VT) in many patients, slowing or preventing induced VT. However, heart failure risks persist, especially with reduced left ventricular function.
Area of Science:
- Cardiology
- Electrophysiology
- Pharmacology
Background:
- Ventricular tachycardia (VT) poses a significant challenge, often requiring multiple antiarrhythmic drugs.
- Patients with refractory VT have limited therapeutic options, necessitating evaluation of alternative treatments.
Purpose of the Study:
- To assess the electrophysiologic effects and antiarrhythmic efficacy of flecainide in patients with refractory VT.
- To determine flecainide's effectiveness as a monotherapy or in combination with other agents for chronic VT management.
Main Methods:
- Electrophysiologic studies (EPS) were conducted on 20 patients with refractory VT, both without and with steady-state oral flecainide therapy.
- Flecainide's impact on QRS duration, PR interval, and ventricular effective refractory periods was measured.
- VT inducibility and characteristics were assessed during EPS under flecainide treatment.
Main Results:
- Flecainide significantly prolonged QRS duration and PR interval, and increased ventricular effective refractory periods.
- Flecainide prevented VT induction in 5 patients and slowed induced VT in 3 others.
- 13 of 20 patients received chronic flecainide therapy (alone or with amiodarone), with 9 remaining on treatment after 9 months. Three recurrences of slow VT occurred, with no sudden deaths.
Conclusions:
- Low-dose flecainide demonstrates efficacy in selected patients with refractory VT, either as monotherapy or in combination regimens.
- While effective, flecainide's use requires careful consideration of potential side effects, particularly worsening heart failure in patients with compromised left ventricular function.