Antiarrhythmic efficacy and hemodynamic effects of cibenzoline in patients with nonsustained ventricular tachycardia and left ventricular dysfunction

Heart Failure Elevates Serum Levels of Cibenzoline in Arrhythmic Patients

BACKGROUND

Cibenzoline dosing is generally based on renal function, but serum concentrations might be greater than the expected therapeutic levels when standard oral dosing is used. Because heart failure might modify cibenzoline pharmacokinetics, the difference in cibenzoline pharmacokinetics between patients with and without heart failure was evaluated.

METHODS AND RESULTS

The study enrolled 368 patients (233 men, 135 women) that had been hospitalized and received cibenzoline therapy at the National Cardiovascular Center from January 2001 to May 2005. There were 89 patients with heart failure (51 men, 38 women) and 279 patients without heart failure (182 men, 97 women). They had therapeutic drug monitoring > or = 3 days after the beginning of treatment with cibenzoline. Brain natriuretic peptide (BNP) was measured in 81 patients (50 men, 31 women) concurrently with therapeutic drug monitoring of cibenzoline. The difference in serum cibenzoline concentration/(dose/weight) (C/D) values between patients with and without heart failure was analyzed using analysis of covariance (ANCOVA) with creatinine clearance (Ccr) serving as the covariate. The effects of dose/weight and the log-transformed BNP (log-BNP) values on serum cibenzoline concentrations were also assessed using ANCOVA. There were 135 and 361 measurements of serum cibenzoline concentration in patients with and without heart failure, respectively. Pearson's correlation coefficient analyses in the patients with and without heart failure revealed that the C/D values were significantly correlated with Ccr (with heart failure, y = -0.837x + 169, r = -0.211, p = 0.014; without heart failure, y = -0.789x + 132, r = -0.393, p < 0.001), and the ANCOVA model indicated that C/D values were significantly higher in patients with heart failure than without heart failure. The ANCOVA model also showed that dose/weight, Ccr and the log-BNP value were significant factors.

CONCLUSIONS

The selection of a cibenzoline dose based only on renal function may increase the risk of toxicity in patients with heart failure. Cardiac function should be taken into account in cibenzoline dosing. The log-BNP may be a useful index for predicting serum cibenzoline concentrations.

Effects of the Na+ antagonist cibenzoline on left ventricular function of postischemic hearts

The negative inotropic effect of antiarrhythmic drugs is a major drawback in antiarrhythmic drug therapy, especially in patients with reduced contractile function of the left ventricle. The circulatory and myocardial effects of the new class I antiarrhythmic drug (a Na+ antagonist), cibenzoline (2 mg/kg i.v.), were investigated in 47 open-chest rats with normal and postischemic myocardium (3 x 4 minutes of global ischemia). Hemodynamic measurements in the intact circulation and isovolumic registrations (peak isovolumic left ventricular systolic pressure and peak isovolumic dP/dtmax) were compared to saline controls. In rats with postischemic myocardium, cibenzoline caused a significant (p < 0.001) decrease in the cardiac output for 38%, in the dP/dtmax for 30%, and in the peak isovolumic dP/dtmax for 19% at the end of infusion (compared to the control). The heart rate was reduced by 22% (p < 0.001), the mean aortic pressure by 22% (p < 0.001), and the calculated systemic resistance by 20% (p < 0.001). In contrast to the results with postischemic myocardium, no important changes in the hemodynamics were detectable after an identical dose in normal animals without left ventricular dysfunction. The results indicate that standard doses of the Na+ antagonist cibenzoline may induce significant cardiodeperessant effects on postischemic left ventricles with reduced function.

Intravenous cibenzoline in the management of acute supraventricular tachyarrhythmias

Intravenous cibenzoline was evaluated in 37 patients with acute supraventricular tachyarrhythmias and a ventricular rate > 120 beats/min. The presenting arrhythmia was atrial fibrillation in 15 patients, atrial flutter in 5, ectopic atrial tachycardia in 11, and paroxysmal atrioventricular (AV) junctional reentrant tachycardia in 6 patients. Intravenous cibenzoline was administered as a bolus given over 2 minutes, at a dose of 1 mg/kg in the first 26 patients and 1.2 mg/kg in the subsequent 11 patients, 15 minutes following failure of placebo (isotonic glucose). The results were evaluated 15 minutes after the intravenous injection. Restoration of sinus rhythm was obtained in 3 out of 6 patients with paroxysmal AV junctional tachycardia (50%) and in 7 out of 31 patients (23%) with atrial tachyarrhythmias (5 out of 15 patients with atrial fibrillation and 2 out of 16 patients with ectopic atrial tachycardia or atrial flutter). Five additional patients with atrial tachyarrhythmias had slowing of ventricular rate below 100 beats/min. Therefore, a satisfactory result, that is, restoration of sinus rhythm or slowing of ventricular rate, occurred in 15 patients (40.5%). Side effects were transient, including visual disturbance (one patient), asymptomatic widening of QRS complex (three patients), incessant reciprocating tachycardia (one patient), and acceleration of ventricular rate (eight patients), resulting in 1:1 flutter, with poor tolerance in two patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship between negative inotropic and chronotropic effects of tocainide and five class I antiarrhythmic drugs in the coronary perfused guinea-pig heart

1. The relationship between the negative inotropic and chronotropic effects of tocainide and 5 other class I antiarrhythmic drugs was evaluated in Langendorff-perfused guinea-pig hearts. 2. All 6 drugs reduced the contractile force (Fc) and the heart rate (HR) of spontaneously beating guinea-pig hearts in a dose-dependent manner. The order of crude negative inotropic potency was: quinidine (Qui) = aprinidine (Apr) > mexiletine (Mex) > lidocaine (Lid) > disopyramide (Dis) > tocainide (Toc); and the order of negative chronotropic effect was: Apr > Qui > Mex > Dis > Lid > Toc. 3. The order of the negative inotropic potency relative to chronotropic effect (expressed as a ratio: ID50 for Fc/ID50 for HR) was Lid > Qui > Dis > Toc > Mex > Apr (n = 6). 4. For heart electrically stimulated at a constant rate, the order of crude negative inotropic potency was: Apr > Qui > Mex > Dis > Lid > Toc, and the order of negative inotropic potency (determined by the ratio: ID50 for Fc in driven heart/ID50 for spontaneously beating HR) was: Mex > Apr > Toc > Dis > Qui > Lid (n = 6). 5. There was a significant influence of negative chronotropic effect on the inotropic potency and the order was: Lid > Qui > Dis > Toc > Apr > Mex. The potency of various drugs is clinically useful in the choice of drugs when considering cardiac function and heart rate.

Effects of hypoxia on the use-dependent inhibition of conduction velocity induced by cibenzoline in guinea pig ventricular myocardium

The use-dependent effects of cibenzoline, a new anti-arrhythmic drug, on the maximal rate of rise (Vmax) of the action potential and on conduction velocity, and their corresponding recovery kinetics were studied in isolated papillary muscles of guinea pigs under normal and hypoxic conditions. Standard microelectrode techniques were applied to monitor the action potential of the muscles and their conduction. Under control conditions, the amount of use-dependent block of Vmax, conduction velocity, and square of conduction velocity, induced by 10 mumol/L cibenzoline were 26.5 +/- 3.9, 13.8 +/- 1.4, and 25.6 +/- 2.4%, respectively; under hypoxic conditions, these values increased to 32.3 +/- 4.8, 19.7 +/- 1.2, and 35.5 +/- 2.0%, respectively. In the presence of 10 mumol/L cibenzoline, the mean values of time constants for the onset of the use-dependent inhibition of Vmax, conduction velocity, and the square of conduction velocity, during a 2-Hz stimulation, were 3.65 +/- 0.27, 2.77 +/- 0.33, and 2.56 +/- 0.26 seconds, respectively. Under hypoxic conditions, these values changed to 5.10 +/- 0.96, 3.05 +/- 0.44, and 2.84 +/- 0.39 seconds, respectively. The recovery time constants averaged 14.72 +/- 4.08 seconds (for Vmax), 22.23 +/- 3.78 seconds (for conduction velocity), and 23.17 +/- 13.38 seconds (for the square of conduction velocity) in the presence of 10 mumol/L cibenzoline, and 17.19 +/- 8.59 seconds (for Vmax), 15.77 +/- 2.37 seconds (for conduction velocity), and 16.82 +/- 2.61 seconds (for the square of conduction velocity) under hypoxic conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Cibenzoline. A review of its pharmacological properties and therapeutic potential in arrhythmias

Cibenzoline is a class I antiarrhythmic drug with limited class III and IV activity which can be administered orally or intravenously. An elimination half-life of about 8 to 12 hours permits twice daily administration, although age and renal function must be considered when determining dosage. Cibenzoline has some activity in ventricular and supraventricular arrhythmias, including drug-refractory ventricular tachycardia or ventricular arrhythmias following recent acute myocardial infarction, although results in patients with sustained ventricular tachycardia are less promising. In comparative trials, cibenzoline has demonstrated efficacy similar to or better than that of a variety of other class I antiarrhythmic drugs and was at least as well tolerated, with a more convenient dosage schedule. However, further studies to clarify the proarrhythmic effects of cibenzoline and its use in patients with impaired left ventricular function are required, and the use of cibenzoline (and other class I antiarrhythmic agents) in patients with other than potentially lethal ventricular arrhythmias should be avoided following the results of the CAST studies. Thus, cibenzoline is an effective antiarrhythmic agent with a favourable pharmacokinetic profile that may be considered with other class I drugs in patients requiring therapy for high risk arrhythmias.

Antiarrhythmic and hemodynamic evaluation of indecainide and procainamide in nonsustained ventricular tachycardia

The present trial was a placebo-controlled, randomized, parallel study comparing indecainide to procainamide. A 24-hour intravenous phase measured and compared invasive hemodynamics, followed by oral administration for assessment of arrhythmia suppression. Thirty-two patients (mean age 61 years) with asymptomatic or mildly symptomatic nonsustained ventricular tachycardia (VT) were evaluated, 15 while receiving indecainide and 17 while receiving procainamide. A total of 8 patients had serious toxicity during the intravenous phase; 6 receiving indecainide experienced increased left ventricular dysfunction or worsening arrhythmia (sustained VT, arrhythmic death) while 2 receiving procainamide developed serious hypotension. Proarrhythmia developed in 3 of 15 (20%) of the indecainide patients, but in no procainamide patient. In those tolerating indecainide, long-term suppression of ventricular premature complexes (VPCs) and of runs of VT was more consistent than with procainamide. While indecainide was a potent suppressor of spontaneous VPCs and VT, patients with significant left ventricular dysfunction could not tolerate it. The indecainide patients developing serious toxicity had a common hemodynamic profile: ejection fraction less than 25%, elevated left ventricular filling pressures, low cardiac and stroke volume index and minimal cardiac reserve. Indecainide has a poor risk-benefit ratio in patients similar to the current population, who have potentially lethal ventricular arrhythmias and severe left ventricular dysfunction.

Hemodynamic effects of intravenous and oral sotalol

Beta-adrenergic blocking agents may have negative inotropic effects that are particularly worrisome in patients with depressed cardiac function. Their membrane-stabilizing properties may be a contributing factor. Sotalol is currently thought not to cause significant myocardial depression. Intravenous sotalol administration has minimal effects on resting stroke volume, although heart rate and consequently cardiac output are significantly decreased. Systolic blood pressure decreases, with a minimal change in diastolic or mean pressure. Hemodynamic effects are usually seen within 15 to 20 minutes of administration. Hemodynamic indexes are maintained even in patients with mildly depressed ejection fractions (mean ejection fraction of 43 +/- 15%) after oral sotalol administration. Although heart rate decreases, cardiac index is unchanged because of a significant increase in stroke volume index. The latter results from an increase in preload (secondary to bradycardia) and a decrease in afterload. Sotalol is well tolerated, although occasionally it may cause worsening heart failure. This is seen in patients with markedly depressed left ventricular function and inadequate cardiac reserve characterized by an inability to increase stroke volume and cardiac output with exercise. Long-term (1-year) patient follow-up reveals no significant hemodynamic deterioration from initial values obtained after oral administration.

The inverse relationship between baseline left ventricular ejection fraction and outcome of antiarrhythmic therapy: a dangerous imbalance in the risk-benefit ratio

Each year, millions of prescriptions are written for antiarrhythmic drug suppression of ventricular arrhythmias. A large portion of these prescriptions are written for patients with asymptomatic, complex ventricular arrhythmias and organic heart disease, termed "potentially malignant" or "potentially lethal." Since arrhythmia suppression in this population is of unproven benefit, we performed the following study: A total of 246 patients (42% with significant left ventricular dysfunction) had complex ventricular arrhythmias, and were treated with one of eight antiarrhythmic drugs (Vaughan Williams classes IA, IB, IC, II, and III). The extent of arrhythmia suppression and the development of serious complications resulting from therapy after 2 weeks was of primary interest. A total of 82 of 246 (33%) maintained adequate (protocol definition) suppression of both ventricular premature beats (VPBs) as well as nonsustained ventricular tachycardia (VT) for 2 weeks, mostly in patients with left ventricular ejection fraction (LVEF) greater than or equal to 40% (p = 0.04 versus LVEF less than 40%). Life-threatening complications of antiarrhythmic therapy occurred most frequently in the 61 patients with an LVEF less than 30% compared to the 185 patients with LVEF greater than or equal to 30% (15% versus 2.1%, p = 0.0005). Suppression of VT was achieved nearly twice as commonly in patients with an LVEF greater than or equal to 30% than in those with an LVEF less than 30% (67% versus 36%; p = 0.0008). Life-threatening complications occurred seven times as frequently in patients presenting with nonsustained VT and an LVEF less than 30% (18% versus 2.3%; p = 0.003).(ABSTRACT TRUNCATED AT 250 WORDS)

Newer antiarrhythmic drugs

The effective management of cardiac arrhythmias remains a major challenge in cardiovascular therapeutics. The management of arrhythmias encompasses a wide spectrum of supraventricular and ventricular tachyarrhythmias occurring in patients with various cardiac diagnoses and different degrees of myocardial dysfunction. A number of the newer antiarrhythmic drugs that have either recently been released or appear promising are reviewed in this article. Drugs are described with respect to their basic pharmacology, electrophysiologic actions, pharmacokinetics and metabolism, hemodynamics, antiarrhythmic effects, side effects, interactions, indications, and dosage.