Safety and efficacy of oral flecainide therapy in patients with atrioventricular re-entrant tachycardia

Article Abstract:

Flecainide acetate, a drug that prevents arrhythmias (abnormal heart rhythms), has been shown to be effective in preventing supraventricular arrhythmias, abnormal heart rhythms arising in heart tissue above the ventricles. Flecainide given intravenously has also been shown to prevent certain types of tachycardia (a type of rapid heart rate) and atrial fibrillations, which are extremely rapid, incomplete contractions of the atria resulting in fine, irregular, and uncoordinated movements. However, a recent study indicated that flecainide treatment is associated with an increased incidence of sudden death in heart attack patients. The safety and effectiveness of flecainide given orally was assessed in 63 patients with extranodal accessory pathways (routes that support major conduction pathways in the heart) and supraventricular tachycardia. Treatment with flecainide slowed the tachycardia in 44 of 63 patients. Flecainide treatment was continued in 33 of 44 patients discharged from the hospital, and did not cause adverse effects in these patients over an average follow-up period of 24 months. Adverse effects on the heart associated with flecainide treatment developed in 11 of 63 patients, including nine patients with abnormalities detected in the hospital or before discharge. Adverse cardiac events occurred in 8 of 11 patients with structural abnormalities, and in 6 of 52 patients without structural disorders. The drug isoproterenol counteracted the effects of flecainide treatment in 11 of 21 patients, causing recurrent tachycardia or palpitations in 7 of 11 patients. In contrast, these symptoms developed in only 1 of 10 patients without signs of isoproterenol reversal of flecainide. These findings show that flecainide treatment was effective in managing 33 patients with supraventricular tachycardia and extranodal accessory pathways. However, patients should initially be assessed in the hospital before treatment with flecainide, which should be used carefully in patients with structural heart disease. (Consumer Summary produced by Reliance Medical Information, Inc.)

Abnormalities, Complications and side effects, Heart, Cardiovascular abnormalities, Supraventricular tachycardia

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Inefficacy and proarrhythmic effects of flecainide and encainide for sustained ventricular tachycardia and ventricular fibrillation

Article Abstract:

Cardiac arrhythmias, or heart rhythms characterized by irregular beating of the heart, may be fairly innocuous or may even cause sudden death. The anti-arrhythmia drugs flecainide and encainide are remarkably effective in suppressing ventricular (major pumping chamber of the heart) arrhythmias. However, a recent study found an increased incidence of sudden cardiac death and total mortality in patients who were given these anti- arrhythmia agents for ventricular arrhythmias following heart attack. Flecainide and encainide have since been recommended for use only in suppressing life-threatening ventricular arrhythmias. These drugs can decrease the force of heart contractility and, consequently, their use in patients with decreased left ventricular function caused by heart disease or failure may be problematic. In addition, the drugs may not be as effective in patients with sustained ventricular arrhythmias. The effectiveness of flecainide and encainide in 49 patients with sustained ventricular tachycardia (rapid heartbeat) was studied. Arrhythmias worsened in 3 of 33 flecainide-treated patients and 5 of 16 patients who were given encainide; patients with poor left ventricular function were more likely to have increased arrhythmias. Ventricular tachycardia could still be induced in most of the patients treated with these anti-arrhythmia drugs when they were retested. Three hospital deaths occurred despite careful monitoring. The findings indicate that flecainide and encainide should be limited to use in patients with normal or nearly normal ventricular functioning. (Consumer Summary produced by Reliance Medical Information, Inc.)

Causes of, Ventricular fibrillation, Arrhythmia, Encainide hydrochloride, Encainide, Anti-arrhythmia drugs, Antiarrhythmia agents

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Adenosine for paroxysmal supraventricular tachycardia: dose ranging and comparison with verapamil: assessment in placebo-controlled, multicenter trials

Article Abstract:

Adenosine is a naturally occurring (endogenous) substance found throughout the body. It is known to have physiologic effect on the physiologic electrical systems such as are in the heart. The hypothesis that it may be useful in treating heart arrhythmias has only recently been tested. Adenosine is cleared from the body rapidly, either by being transported across membranes into cells or by being rapidly degraded by enzymes. Paroxysmal supraventricular tachycardia (PSVT) is a troublesome heart arrhythmia that is the result of a dysfunction in certain electrical centers (nodes) in the heart that causes too-rapid beating of the atria of the heart. Because of the way in which adenosine works in those centers, it has been hypothesized (and shown in uncontrolled studies) that it would be a good treatment for PSVT if given intravenously in quick doses. The hypothesis has been proven now in a multicenter, double-blind, randomized trial that compares adenosine to verapamil, a drug commonly used to treat PSVT. Although the adverse effects of verapamil were seen less frequently than those associated with adenosine, those from verapamil lasted longer. Adenosine in doses up to 12 mg is highly effective in stopping, for the short term, episodes of PSVT in the presence of intact atrioventricular node conduction that would allow the tachycardia to continue. Its action is similar to that of verapamil, but it acts sooner, which is worth considering when treating PSVT. (Consumer Summary produced by Reliance Medical Information, Inc.)

Adenosine, Verapamil, Paroxysmal tachycardia

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