Combination of tocainide and quinidine for better tolerance and additive effects in patients with coronary artery disease

Use of a combination of class III and class Ic antiarrhythmic agents in patients with electrical storm

STUDY OBJECTIVE

To determine the efficacy of the combination of class III and class Ic antiarrhythmic agents in suppressing an electrical storm in patients with and without a transvenous implantable cardioverter-defibrillator (ICD).

DESIGN

Retrospective medical record review.

SETTING

Arrhythmia service of an academic medical center in Zerifin, Israel.

PATIENTS

Ten patients who experienced an electrical storm that was not effectively treated with amiodarone or sotalol monotherapy between December 15, 1999, and June 13, 2007.

MEASUREMENTS AND MAIN RESULTS

The medical records of 152 patients who received an ICD during the study period were reviewed. Twenty patients experienced an electrical storm, an arrhythmia defined as more than two episodes of hemodynamically unstable ventricular tachycardia during a 24- hour period. Ten of the 20 patients responded favorably to amiodarone or sotalol monotherapy (class III antiarrhythmics), but in 10 patients, the combination of a class III and a class Ic antiarrhythmic agent was needed to effectively eliminate the electrical storm. Of the 10 patients who required both agents, two (20%) developed an electrical storm before implantation of their ICD. In another patient who had ongoing ischemia, ventricular tachycardia recurred, but the drug combination decreased the number of ventricular arrhythmia episodes. One patient with dilated cardiomyopathy had one recurrence of ventricular tachycardia, which was terminated with antitachycardia pacing. Three patients died during a mean +/- SD follow-up of 8.7 +/- 9.9 months.

CONCLUSION

Electrical storm can be acutely treated with the combination of a class III and a class Ic antiarrhythmic agent when a class III agent alone is insufficient and when radiofrequency ablation is not an option. Patients receiving this drug combination can be discharged from the hospital only if they have an ICD.

Efficacy and safety of combination therapy with amiodarone and type I agents for treatment of inducible ventricular tachycardia

In a prospective study the efficacy of amiodarone in combination with the three Class I drugs mexiletine, flecainide, or encainide was evaluated consecutively in 12 patients with recurrent ventricular tachycardias (VT) by programmed stimulation. None of the tested drug combinations suppressed induction of sustained VT. The combination of amiodarone with Class IC drugs flecainide and encainide prolonged the cycle length of VT significantly, whereas the combination with mexiletine did not have the same degree of slowing on the VT cycle length. Several proarrhythmic effects occurred during the combination therapy with encainide: (1) frequent, spontaneous recurrences of hemodynamically well tolerated VT in four patients; (2) enhanced inducibility of VT in three patients; (3) impaired termination of VT in three patients. Though a marked increase in QRS and QTc intervals was observed by combined treatment with encainide, no significant correlation could be established between aggravation of arrhythmia and plasma levels of encainide, degree of QRS widening, JT or QTc prolongation. The only predictor for the occurrence of proarrhythmic events was found in left ventricular ejection fraction. These findings suggest that in patients refractory to amiodarone alone or a combination with mexiletine, the combined treatment of amiodarone with other Class IC drugs prolongs the VT cycle length but does not suppress induction of VT during programmed stimulation. Combination therapy of amiodarone with encainide was associated with a high incidence of proarrhythmic effects.

Efficacy of disopyramide and mexiletine used alone or in combination in the treatment of ventricular premature beats

The efficacy of oral disopyramide and mexiletine used alone or in combination was studied in 75 patients with frequent ventricular premature beats (VPBs). The efficacy was evaluated with 24-hour ambulatory ECG and greater than or equal to 75% reduction in the number of VPBs was defined as effective. When disopyramide or mexiletine were ineffective or not tolerated, the alternative drug was administered and the efficacy was again evaluated. If the single administration of neither drug was effective, the combination of disopyramide and mexiletine was then given. Either disopyramide or mexiletine was effective in 48 patients, and neither drug was effective in 19 patients. In 19 patients unresponsive to both drugs, combination therapy was effective in six patients (32%). Both drugs caused side effects or one drug caused side effects and another drug was ineffective in eight patients. In five out of those patients, we attempted combined therapy with a reduced dosage of those drugs that caused side effects. This therapy was effective in two patients without intolerable side effects. Thus, when the single use of neither disopyramide nor mexiletine single-drug therapy is effective, it is worthwhile to try combination therapy. Also, combination therapy with a reduced dosage of the drugs that caused side effects might be the therapy of choice in patients who have developed dose-dependent side effects.

Randomized double-blind study of intravenous tocainide versus lidocaine for suppression of ventricular arrhythmias after cardiac surgery

To compare the therapeutic efficacy and safety of intravenous tocainide with that of intravenous lidocaine in patients with ventricular arrhythmias after cardiac surgery, 25 patients were randomized to either agent in a double-blind manner. Tocainide was given in 16 patients as a 250 mg bolus followed by a loading infusion of 500 mg over 15 minutes and a maintenance infusion of 33.3 mg/min. Lidocaine was administered in 9 patients as a 100 mg bolus followed by a loading infusion of 60 mg over 15 minutes and a maintenance infusion of 1.4 mg/min. Therapy was continued for 24 hours in initially responding patients. With analysis of 24-h taped electrocardiograms it was found that single premature ventricular complexes (PVCs) were suppressed by tocainide by more than 80% in 94% of patients and by lidocaine in 75% of patients (p = NS). Couplets and ventricular tachycardia events were eliminated in all patients by either drug. Multiform PVCs were abolished in 94% of the patients after tocainide and in 75% after lidocaine (p = NS). Average overall success over the 24 hours with more than 80% suppression of single PVCs and simultaneous elimination of higher forms of arrhythmia was 71% with tocainide and 59% with lidocaine (p = NS). Adverse effects were negligible, with only one patient in the lidocaine group developing diaphoresis without necessitating termination of therapy. Treatment rapidly produced and then maintained blood levels of 4-10 mg/l for tocainide and 1-4 mg/l for lidocaine. We conclude that intravenous tocainide is well tolerated and has comparable efficacy to lidocaine in the acute therapy of postcardiac surgery ventricular arrhythmias.

Acute effects of combination of IB and IC antiarrhythmics for the treatment of ventricular tachycardia

There are limited data on the effects of Class IB and IC antiarrhythmic drug combination for the treatment of ventricular tachycardia. The present study evaluated this combination in 12 patients who had sustained ventricular tachycardia (SuVT) during programmed electrical stimulation (PES) and failed IC antiarrhythmic therapy. Following combination of lidocaine and a IC agent (7 with encainide and 5 with flecainide), two had no inducible ventricular tachycardia (VT) and one had nonsustained VT (NSVT). In seven of nine patients who still had SuVT, the mean VT cycle length increased 40 +/- 25 msec post combination compared to IC antiarrhythmic therapy. Seven patients who had a favorable response to the initial combination (less than 10 beats of NSVT, or greater than or equal to 10 beats of VT with a greater than 100 msec increase in cycle length compared to baseline and no hemodynamic compromise) were then placed on IC + oral IB agent (5 with mexiletine, 2 with tocainide). Similar effects on VT inducibility and cycle length were observed following the oral combination. In conclusion, the addition of lidocaine to IC therapy produced favorable effects on induced ventricular tachycardia in 58% of patients compared to IC agent alone. Also, a positive PES response to lidocaine and IC therapy corresponded to a similar positive response when either mexiletine or tocainide was substituted for lidocaine.

Combination antiarrhythmic therapy for management of malignant ventricular arrhythmia

The efficacy of combination drug therapy in the suppression of ambient ventricular arrhythmia was retrospectively evaluated in a study of 49 patients discharged from the hospital taking 2 membrane-active antiarrhythmic agents. Thirty-one patients (63%) had ischemic heart disease, 15 had miscellaneous cardiac disorders and 3 were free of ostensible heart disease. Therapy in all patients had previously been unsuccessful with an average of 3.7 single membrane-active drugs. Antiarrhythmic agents were discontinued for at least 48 hours to determine baseline arrhythmia levels by Holter monitoring and maximal exercise treadmill testing. Ventricular premature beats were evaluated according to the grading system of Lown and Wolf. Data on ventricular ectopic activity were obtained during Holter monitoring and exercise testing for both a control ("drug-free") period and for a period of combination therapy. During the control period, ventricular tachycardia was recorded during 23% of monitored hours, and the level was nearly twofold greater during stress testing. After institution of combined therapy, the percent of monitored hours of arrhythmia were reduced during Holter monitoring, with a greater reduction in couplets and ventricular tachycardia than in single ventricular premature beats. Ventricular tachycardia was more difficult to provoke by exercise testing in patients taking combination therapy than in control subjects. These data indicate that combination therapy can significantly reduce the density of ventricular ectopic activity in patients refractory to monotherapy. During an average follow-up of 26 months, 23 patients (47%) were able to receive decreased drug dosages, affording diminished adverse effects and improved tolerance to long-term use.

Role of the electrocardiogram in determining electrophysiologic end points of drug therapy

Electrocardiographic monitoring can be a useful adjunct to antiarrhythmic therapy, since the electrocardiogram is a simple indicator of net cardiac drug effect, irrespective of factors such as pharmacokinetic variability, drug-metabolite interactions or intraindividual variability in drug sensitivity. Changes associated with antiarrhythmic drug therapy include markers of sodium channel block, such as increased QRS or sinus-ectopic coupling intervals and increased QT interval, a marker of action potential prolongation. Electrocardiographic changes can serve 3 purposes: They can correlate with arrhythmia suppression, they may be a guide to impending drug toxicity, and they can indicate the presence of an antiarrhythmic drug at some electrophysiologically active site in the heart. This latter indication may be used as an assessment of compliance, as a clue to drug-drug interactions that may lower antiarrhythmic drug concentrations or preparatory to electrophysiologic testing when it is desirable to avoid testing patients who have no demonstrable drug effect. Drug-induced changes in the microelectrophysiologic environment may sometimes fail to express themselves on the surface electrocardiogram. Overall, however, the electrocardiogram is an inexpensive, readily available tool to monitor net antiarrhythmic drug effects on the heart. Monitoring of the electrocardiogram should, therefore, be an integral part of managing antiarrhythmic drug therapy in patients with arrhythmias.

Electrophysiologic evaluation of antiarrhythmic therapy for ventricular tachyarrhythmias

The use of electrophysiologic studies has contributed significantly to our understanding of the mechanisms of ventricular tachyarrhythmias and enhanced our ability to assess objectively the efficacy of various therapeutic interventions in modifying or preventing their recurrence. The basis on which electrophysiologic testing techniques is founded is the ability reproducibility to initiate ventricular arrhythmias by programmed electrical stimulation in patients with a history of recurrent ventricular tachycardia or fibrillation. Ventricular tachycardia can be initiated by electrophysiologic studies in approximately 90% of patients with clinically documented recurrent, sustained ventricular tachycardia related to coronary artery disease and in 60% of patients with nonsustained ventricular tachycardia. Reports indicate that electrophysiologic testing is highly specific as well (99% for sustained monomorphic ventricular tachycardia). Studies in patients with recurrent ventricular tachycardia demonstrate that prevention by antiarrhythmic drugs of the ability to initiate tachycardias that were previously inducible by comparable stimulation techniques in the absence of therapy is highly predictive of freedom from recurrent episodes of spontaneous ventricular tachycardia and ventricular fibrillation. This end point can be achieved in 35 to 75% of patients. This wide range of success rates results from differences in the patient populations studied, as well as major differences in the programmed stimulation and antiarrhythmic drug protocols used among laboratories. The positive predictive value of this technique (defined as the percentage of patients in whom complete suppression of inducible ventricular tachycardia or ventricular fibrillation is achieved during electrophysiologic testing with antiarrhythmic drugs and in whom no spontaneous arrhythmia occurs at 1- to 2-year follow-up) ranges between 80 and 95%.

Tocainide plus quinidine for treatment of ventricular arrhythmias

Tocainide and quinidine were administered both as single agents and in combination to 14 patients with chronic ventricular arrhythmias. Therapy with tocainide was limited by the occurrence of dose-related adverse reactions in 8 patients, but could be titrated to a dose that was well-tolerated in 13 of 14 and effective in 2 of 13. The addition of quinidine gluconate to the tolerated dose of tocainide increased the number of patients with arrhythmia suppression from 2 to 6. After tocainide washout, quinidine alone suppressed arrhythmias in only 3 patients. Analysis of electrocardiogram intervals showed that the drugs had additive effects on the coupling interval of the sinus beat to the predominant ectopic beat, but exerted antagonistic effects on the corrected QT interval. These findings suggest that the combination may be clinically useful, exerting pharmacologic effects unlike either agent alone.