Antiarrhythmic drugs with other antiarrhythmics

In applied medicine, however, only one drug of this group, propranolol, is represented. Publications on using atenolol as an antiarrhythmic have appeared. There is no contradictory evidence for using 8-blockers with other antiarrhythmics. 

As with other antiarrhythmic drugs, moricizine has proarrhythmic activity, which may manifest as new ventricular ectopic beats or a worsening of preexisting ventricular arrhythmias. These effects are most common in patients with depressed left ventricular function and a history of congestive heart failure. Cardiovascular ef-... 

The biosynthetic pathway for ajmaline in R. serpentina is one of the best-characterized terpenoid indole alkaloid pathways. Much of this progress has been detailed in a recent extensive review (78). Like all other terpenoid indole alkaloids, ajmaline, an antiarrhythmic drug with potent sodium channel-blocking properties (79), is derived from deglycosylated strictosidine (Fig. 2c). 

Roden DM. Use of mexiletine in combination with other antiarrhythmic drugs. Clin Progr Electrophysiol Pacing 1986 4 561-7. 

Amiodarone is a Type III antiarrhythmic agent. It has been shown in several clinical trials to be safe and effective in the treatment of supraventricular and ventricular arrhythmias in patients with cardiovascular disease. Amiodarone is also associated with fewer proarrhythmic effects compared with other antiarrhythmic drugs. Amiodarone is empirically dosed and adjusted based on efficacy and toxicity. 

B. Cardiac-depressant effects may be additive with other antiarrhythmic dmgs, particularly type la and type Ic drugs. 

FIGURE 6-2. Algorithm for the treatment of acute (top portion) paroxysmal supraventricular tachycardia and chronic prevention of recurrences (bottom portion). Note For empiric bridge therapy prior to radiofrequency ablation procedures, calcium channel blockers (or other atrioventricular [AV] nodal blockers) should not be used if the patient has AV reentry with an accessory pathway. (AAD, antiarrhythmic drugs AF, atrial fibrillation AP, accessory pathway AVN, atrioventricular nodal AVNRT, atrioventricular nodal reentrant tachycardia AVRT, atrioventricular reentrant tachycardia DCC, direct-current cardioversion ECG, electrocardiographic monitoring EPS, electrophysiologic studies PRN, as needed VT, ventricular tachycardia.)... 

The applicability of these results to other populations (eg, those without recent Mis) is uncertain. Considering the known proarrhythmic properties of procainamide and the lack of evidence of improved survival for any antiarrhythmic drug in patients without life-threatening arrhythmias, the use of procainamide and other antiarrhythmic agents should be reserved for patients with life-threatening ventricular arrhythmias. 

Concurrent antiarrhythmic agents Concurrent antiarrhythmic agents may produce enhanced prolongation of conduction or depression of contractility and hypotension, especially in patients with cardiac decompensation. Reserve concurrent use of procainamide with other Class lA antiarrhythmic agents (eg, quinidine, disopyramide) for patients with serious arrhythmias unresponsive to a single drug and use only if close observation is possible. 

Hypersensitivity to fluoroquinolones or the quinolone group tendinitis or tendon rupture associated with quinolone use patients receiving disopyramide and amiodarone or other QTc-prolonging antiarrhythmic drugs reported to cause torsade... 

When used with other class IB antiarrhythmic drugs, tocainide toxicity may be increased without significant gain in antiarrhythmic efficacy. 

Amiodarone may elicit life-threatening side effects in addition to presenting substantial management difh-culties associated with its use. The oral formulation of amiodarone is indicated only for the treatment of life-threatening recurrent ventricular arrhythmias (e.g., recurrent ventricular hbrillation and/or recurrent hemo-dynamicaUy unstable ventricular tachycardia) that have not responded to other potentially effective antiarrhythmic drugs or when alternative interventions could not be tolerated. Despite its efficacy as an antiarrhythmic agent, there is no evidence from clinical trials that the use of amiodarone favorably affects survival. 

Cardiac arrhythmias are a common problem in clinical practice, occurring in up to 25% of patients treated with digitalis, 50% of anesthetized patients, and over 80% of patients with acute myocardial infarction. Arrhythmias may require treatment because rhythms that are too rapid, too slow, or asynchronous can reduce cardiac output. Some arrhythmias can precipitate more serious or even lethal rhythm disturbances for example, early premature ventricular depolarizations can precipitate ventricular fibrillation. In such patients, antiarrhythmic drugs may be lifesaving. On the other hand, the hazards of antiarrhythmic drugs—and in particular the fact that they can precipitate lethal arrhythmias in some patients—has led to a reevaluation of their relative risks and benefits. In general, treatment of asymptomatic or minimally symptomatic arrhythmias should be avoided for this reason. 

Antiarrhythmic therapy carries with it a number of risks. In some cases, the risk of an adverse reaction is clearly related to high dosages or plasma concentrations. Examples include lidocaine-induced tremor or quinidine-induced cinchonism. In other cases, adverse reactions are unrelated to high plasma concentrations (eg, procainamide-induced agranulocytosis). For many serious adverse reactions to antiarrhythmic drugs, the combination of drug therapy and the underlying heart disease appears important. 

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