Effect of d-sotalol on mortality in patients with left ventricular dysfunction after recent and remote myocardial infarction. The SWORD Investigators. Survival With Oral d-Sotalol

What can we expect from prophylactic implantable defibrillators?

Death due to ventricular tachyarrhythmia (VT) remains an important public health problem; patients with prior myocardial infarction (MI) constitute the largest identifiable population for prophylactic interventions. Targeting of progressively higher-risk subgroups of post-MI survivors carries inevitable tradeoffs with respect to the global impact of interventions on overall mortality. Therapy with aspirin, beta blockers, and angiotensin-converting enzyme (ACE) inhibitors comprise the benchmark against which all additional interventions, including implantable defibrillators, must be measured. Initial enthusiasm for empiric amiodarone therapy has been tempered by the limited benefit demonstrated in recent randomized trials. Trials of other class III antiarrhythmic drugs, including both d,l-sotalol and d-sotalol, have also failed to demonstrate survival benefit. The Multicenter Automatic Defibrillator Implantation Trial (MADIT) demonstrated significantly improved survival associated with defibrillators in a small subgroup of post-MI survivors with a high short-term risk of death. The ultimate number and optimal criteria for selection of patients who may benefit from prophylactic defibrillator therapy after MI will undergo continued evolution as new data from current and ongoing trials become available.

Arrhythmias and sudden death in heart failure

Survival of patients with heart failure has improved over the past decade due to advances in medical therapy. Sudden death continues to cause 20 to 50% of deaths. Ventricular arrhythmias are common in patients with heart failure. Ventricular hypertrophy, scars from prior myocardial infarction, sympathetic activation, and electrolyte abnormalities contribute. Some sudden deaths are due to bradyarrhythmias and electromechanical dissociation rather than ventricular arrhythmias. The risks and benefits of antiarrhythmic therapies continue to be defined. Class I antiarrhythmic drugs should be avoided due to proarrhythmic and negative inotropic effects that may increase mortality. For patients resuscitated from sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) amiodarone or an implantable cardioverter defibrillator (ICD) should be considered. ICDs markedly reduce sudden death in VT/VF survivors, but in advanced heart failure, this may not markedly extend survival. Catheter or surgical ablation can be considered for selected patients with bundle branch reentry VT or difficult to control monomorphic VT. For patients who have not had sustained VT/VF antiarrhythmic therapy should generally be avoided, but may benefit some high risk patients. Amiodarone may be beneficial in patients with advanced heart failure and rapid resting heart rates. ICDs may improve survival in selected survivors of myocardial infarction who have inducible VT.

A pharmacokinetic-pharmacodynamic model of d-sotalol Q-Tc prolongation during intravenous administration to healthy subjects

The objective of this study was to assess the pharmacokinetics and pharmacodynamics of the dextro (d-) isomer of sotalol, a class III antiarrhythmic agent, in healthy young men and women after a single intravenous bolus dose. The design was open-label, randomized, parallel group. Each group (4 men and 4 women) received either 0.5, 1.5, or 3.0 mg/kg d-sotalol as an intravenous infusion for 2 minutes. Serial measurements of the d-sotalol plasma concentration and the Q-Tc interval data were recorded before, during, and for 72 hours after drug administration. The pharmacokinetics of d-sotalol were found to be well described by a three-compartment model with linear elimination clearance from the central compartment. There were no significant differences in the elimination clearance or volume of the central compartment between dose levels or between men and women. However, women were found to have a lower steady-state volume of distribution than men (1.20 L/Kg versus 1.43 L/Kg). The Q-Tc versus d-sotalol plasma concentration data were fitted to a model that assumed a distinct "effect compartment" and sigmoidal Emax response. The baseline Q-Tc, determined from the fittings, was found to be significantly higher in women (0.40 versus 0.38 seconds). The effect compartment clearance was found to be highly variable, with a median of 12.3 (range, 0.2-671,300) L/h. There were statistically significant differences in the effect compartment clearance by dose among men and by gender at a dose of 1.5 mg/kg. There were no significant differences detected between dose groups or genders for the d-sotalol effect site concentration at one half the maximum Q-Tc prolongation from baseline (EC50), EMAX, (the maximum Q-Tc prolongation from baseline) or the Hill coefficient. In conclusion, the pharmacokinetics of d-sotalol after intravenous administration are independent of dose and gender, because the difference between men and women in volume of distribution at steady-state is not clinically significant. The pharmacodynamics of Q-Tc prolongation produced by d-sotalol appear to be independent of dose and gender; however, there is considerable variability in the time course of effects on Q-Tc between individuals.

Reproducible induction of "atypical" torsades de pointes by programmed electrical stimulation: a novel form of sotalol-induced proarrhythmia?

We present a patient with sotalol-induced polymorphic ventricular tachycardia that was seen only with programmed ventricular stimulation. Electrophysiologic studies performed prior to initiation of sotalol therapy revealed inducible monomorphic ventricular tachycardia. Possible underlying electrophysiologic mechanisms are discussed.

The AVID trial: evidence based or randomized control trials--is the AVID study too late? Antiarrhythmics Versus Implantable Defibrillators

A great body of clinical evidence has been accumulated--before and without the AVID trial--showing that implantable defibrillators prolong life better than currently available antiarrhythmic drugs. With this evidence already available, we question the validity of a trial that attempted, in effect, to place a price tag on life and quality of life.

[Prevention of sudden death after myocardial infarction: should the "MADIT" strategy be generally applied? Arguments against]

The Multicenter Automatic Defibrillator Implantation Trial (MADIT) suggests that survival in patients with prior myocardial infarction, asymptomatic unsustained ventricular tachycardia and reduced left ventricular function was better among the patients who received implantable cardioverter defibrillator than that in the drug-treatment group. Nevertheless the absence of data about the efficacy and security of the conventional antiarrhythmic treatment weakness its result and clinical applicability.

Facilitation of epinephrine-induced afterdepolarizations by class III antiarrhythmic drugs

The electrophysiologic actions of epinephrine (10(-9) M, 10(-8) M, and 10(-7) M) were evaluated in canine Purkinje fibers pretreated with the class III antiarrhythmic drugs clofilium (10(-7) M) or d,l-sotalol (10(-6) M). Clofilium and d,l-sotalol prolonged action potential duration at 50% and 90% of repolarization without provoking early afterdepolarization (EAD) or delayed afterdepolarization (DAD). Subsequent administration of epinephrine provoked both bradycardia-dependent EADs and tachycardia-dependent DADs in clofilium-treated Purkinje fibers, with predominantly EADs observed in d,l-sotalol-treated Purkinje fibers. A temporary increase in Ca0(+2) from 1.35 mM to 5 mM suppressed both EADs and DADs. The data demonstrate facilitation of epinephrine-induced EADs and DADs by class III antiarrhythmic drugs. The acute suppression of both EADs and DADs observed following an acute increase in Ca0(+2) suggests inward Na(+)-Ca0(+2) exchange current as a basis for both EADs and DADs observed in the presence of class III antiarrhythmic drugs and epinephrine.

Amiodarone therapy in chronic heart failure and myocardial infarction: a review of the mortality trials with special attention to STAT-CHF and the GESICA trials. Grupo de Estudio de la Sobrevida en la Insuficiencia Cardiaca en Argentina

Amiodarone appears to reduce sudden death in patients with left ventricular dysfunction resulting from an acute MI or a primary dilated cardiomyopathy, particularly if complex ventricular arrhythmias are present. Amiodarone's beneficial effect on mortality in these patients could be unrelated to its antiarrhythmic effects. Multiple factors could account for the improvement in mortality such as the drug's antiischemic effects, neuromodulating effects, its effect on left ventricular function and on heart rate. Moreover, patients with LV dysfunction who have survived an episode of sudden death would potentially benefit from amiodarone therapy. Future trials are needed to determine the precise subsets(s) of patients who would benefit from the drug and the most efficacious dosing regimen for the drug. Based on available data, amiodarone is the only antiarrhythmic agent which has not been shown to increase mortality in patients with chronic heart failure.

Magnesium abolishes inadequate kinetics of frequency adaptation of the Q-aT interval in the presence of sotalol

OBJECTIVE

It has been well established that class III antiarrhythmic drugs can also induce ventricular arrhythmias. Marked changes in the QT interval are correlated with an increased dispersion of repolarization which is an important factor for the induction of ventricular arrhythmias. The aim of the present study was to investigate the effects of sotalol alone and in combination with MgSO4 and the Q-aT interval during abrupt changes in heart rate.

METHODS

The experiments were performed on isolated guinea-pig hearts perfused by the method of Langendorff. The rate adaptation of the Q-aT interval was estimated after abruptly changing the ventricular pacing rate from 220 to 180 ms and back to 220 ms.

RESULTS

In the presence of 10 microM sotalol, at a constant pacing cycle length of 220 ms, the QT interval was prolonged significantly (P < 0.01) from 152 +/- 4 to 166 +/- 3 ms (mean +/- s.e.m., n = 8 in each group). The addition of 3.4 mM MgSO4 caused a slight further prolongation of the QT interval. After abruptly shortening the pacing cycle length from 220 to 180 ms, the Q-aT interval shortened within 2 min by 11.3 +/- 0.5 ms with a time constant (tau) of 77 +/9 beats under control conditions, by 15.4 +/- 0.9 ms (P < 0.05 vs. control with tau = 52 +/- 7 beats (P < 0.05 vs. control) in the presence of sotalol, and by 13.1 +/- 1.2 ms with tau = 158 +/- 13 beats under the combination of sotalol (10 microM) and MgSO4 (3.4 mM). After abrupt shortening of the pacing cycle length the Q-aT interval of the first beat was shortened by 3.3 +/- 0.3 ms under control conditions, by 7.1 +/- 0.2 ms (P < 0.01 vs. control) under sotalol, and by 4.2 +/- 0.2 ms with the combination of sotalol and MgSO4. If the pacing cycle length was abruptly increased from 180 to 220 ms, the effects were comparable to those described above.

CONCLUSIONS

Sotalol led to inadequate kinetics of fate adaptation of the Q-aT interval indicated by a high amplitude of Q-aT interval change, especially within the first beat after abrupt change in the pacing rate. MgSO4 abolished this effect of sotalol. These findings suggest that MgSO4 could reduce sotalol-induced inadequate kinetics of rate adaptation and therefore also dispersion of repolarization, which may result in a reduction of sotalol-induced ventricular arrhythmias.

[Change in therapy of cardiac arrhythmias. Current studies--initial results]

Treatment of Arrhythmias in Development-Recent Trials, First Results When dealing with preliminary or brand new results of large randomised trials, the requirement should be the assessment of the data by experts in the arrhythmia field. This holds especially true for studies addressing the complex problem of the prevention of sudden cardiac death. During recent years a number of controlled randomised trials have been published showing no or a harmful effect of antiarrhythmic drugs on the prognoses of patients at risk of sudden cardiac death. The results of these studies have clearly changed the scenario of preventive antiarrhythmic drug treatments. Some newer studies-published only in a preliminary form-seem to indicate that some Class III antiarrhythmics can have a positive effect. Studies are under way to compare the preventive effect of this antiarrhythmic drug therapy against sudden cardiac death with that of the implantable cardioverter/defibrillator. The improvement of prognosis remains the ultimate goal of antiarrhythmic therapy.

[Drug therapy of ventricular arrhythmias]

In patients with no or only mild structural heart disease, spontaneous ventricular ectopy which causes symptoms is being treated with beta receptor antagonists, sotalol, or in rare cases with class I substances. For primary prevention of sudden death, for instance in survivors of myocardial infarction, beta receptor antagonists are the only substances for which benefit has been demonstrated in large scale trials. In contrast, class I agents are contraindicated for this purpose. In secondary prevention of sudden death in patients with a history of sustained ventricular tachycardia or ventricular fibrillation, treatment with sotalol or amiodarone can be considered. However, nonpharmacological therapy by means of implantable defibrillators is increasingly applied in this patient population.

Randomised trial of losartan versus captopril in patients over 65 with heart failure (Evaluation of Losartan in the Elderly Study, ELITE)

BACKGROUND

To determine whether specific angiotensin II receptor blockade with losartan offers safety and efficacy advantages in the treatment of heart failure over angiotensin-converting-enzyme (ACE) inhibition with captopril, the ELITE study compared losartan with captopril in older heart-failure patients.

METHODS

We randomly assigned 722 ACE inhibitor naive patients (aged 65 years or more) with New York Heart Association (NYHA) class II-IV heart failure and ejection fractions of 40% or less to double-blind losartan (n = 352) titrated to 50 mg once daily or captopril (n = 370) titrated to 50 mg three times daily, for 48 weeks. The primary endpoint was the tolerability measure of a persisting increase in serum creatinine of 26.5 mumol/L or more (> or = 0.3 mg/dL) on therapy; the secondary endpoint was the composite of death and/or hospital admission for heart failure; and other efficacy measures were total mortality, admission for heart failure, NYHA class, and admission for myocardial infarction or unstable angina.

FINDINGS

The frequency of persisting increases in serum creatinine was the same in both groups (10.5%). Fewer losartan patients discontinued therapy for adverse experiences (12.2% vs 20.8% for captopril, p = 0.002). No losartan-treated patients discontinued due to cough compared with 14 in the captopril group. Death and/or hospital admission for heart failure was recorded in 9.4% of the losartan and 13.2% of the captopril patients (risk reduction 32% [95% CI -4% to + 55%], p = 0.075). This risk reduction was primarily due to a decrease in all-cause mortality (4.8% vs 8.7%; risk reduction 46% [95% CI 5-69%], p = 0.035). Admissions with heart failure were the same in both groups (5.7%), as was improvement in NYHA functional class from baseline. Admission to hospital for any reason was less frequent with losartan than with captopril treatment (22.2% vs 29.7%).

INTERPRETATION

In this study of elderly heart-failure patients, treatment with losartan was associated with an unexpected lower mortality than that found with captopril. Although there was no difference in renal dysfunction, losartan was generally better tolerated than captopril and fewer patients discontinued losartan therapy. A further trial, evaluating the effects of losartan and captopril on mortality and morbidity in a larger number of patients with heart failure, is in progress.

Randomised trial of outcome after myocardial infarction in patients with frequent or repetitive ventricular premature depolarisations: CAMIAT. Canadian Amiodarone Myocardial Infarction Arrhythmia Trial Investigators

BACKGROUND

Survivors of acute myocardial infarction with frequent or repetitive ventricular premature depolarisations (VPDs) have higher mortality 1-2 years after the event than those without VPDs. Although there is no therapy of proven efficacy for such patients, previous studies of amiodarone have been encouraging. CAMIAT was a randomised double-blind placebo-controlled trial designed to assess the effect of amiodarone on the risk of resuscitated ventricular fibrillation or arrhythmic death among survivors of myocardial infarction with frequent or repetitive VPDs (> or = 10 VPDs per h or > or = 1 run of ventricular tachycardia).

METHODS

Patients from 36 Canadian hospitals were randomly assigned amiodarone or placebo; a loading dose of 10 mg/kg daily for 2 weeks, a maintenance dose of 300-400 mg daily for 3.5 months, 200-300 mg daily for 4 months, and 200 mg for 5-7 days per week for 16 months. Patients were followed up for 2 years. The primary outcome was the composite of resuscitated ventricular fibrillation or arrhythmic death.

FINDINGS

We recruited 1202 patients (606 in the amiodarone group and 596 in the placebo group). The mean follow-up was 1.79 years (SD 0.44). In the efficacy analysis, resuscitated ventricular fibrillation or arrhythmic death occurred in 39 (6.9%) [corrected] patients in the placebo group and in 25 (4.5%) [corrected] in the amiodarone group (relative-risk reduction 48.5% [95% CI 4.5 to 72.2], p = 0.016). In the intention-to-treat analysis, primary outcome events occurred in 24 (6.9%) patients in the placebo group and in 15 (4.5%) in the amiodarone group (38.2% [95% CI -2.1 to 62.6], p = 0.029). The absolute-risk reductions were greatest among patients with congestive heart failure or a history of myocardial infarction.

INTERPRETATION

Amiodarone reduces the incidence of ventricular fibrillation or arrhythmic death among survivors of acute myocardial infarction with frequent or repetitive VPDs. Treatment decisions for individual survivors should require an assessment of their baseline risk factors and judgments based on the synthesis of our findings with those of related trials.

Randomised trial of effect of amiodarone on mortality in patients with left-ventricular dysfunction after recent myocardial infarction: EMIAT. European Myocardial Infarct Amiodarone Trial Investigators

BACKGROUND

Ventricular arrhythmias are a major cause of death after myocardial infarction, especially in patients with poor left-ventricular function. Previous attempts to identify and suppress arrhythmias with various antiarrhythmic drugs failed to reduce or actually increase mortality. Amiodarone is a powerful antiarrhythmic drug with several potentially beneficial actions, and has shown benefit in several small-scale studies. We postulated that this drug might reduce mortality in patients at high risk of death after myocardial infarction because of impaired ventricular function, irrespective of whether they had ventricular arrhythmias.

METHODS

The European Myocardial Infarct Amiodarone Trial (EMIAT) was a randomised double-blind placebo-controlled trial to assess whether amiodarone reduced all-cause mortality (primary endpoint) and cardiac mortality and arrhythmic death (secondary endpoints) in survivors of myocardial infarction with a left-ventricular ejection fraction (LVEF) of 40% or less. Intention-to-treat and on-treatment analyses were done.

FINDINGS

EMIAT enrolled 1486 patients (743 in the amiodarone group, 743 in the placebo group). Median follow-up was 21 months. All-cause mortality (103 deaths in the amiodarone group, 102 in the placebo group) and cardiac mortality did not differ between the two groups. However, in the amiodarone group, there was a 35% risk reduction (95% CI 0-58, p = 0.05) in arrhythmic deaths.

INTERPRETATION

Our findings do not support the systematic prophylactic use of amiodarone in all patients with depressed left-ventricular function after myocardial infarction. However, the lack of proarrhythmia and the reduction in arrhythmic death support the use of amiodarone in patients for whom antiarrhythmic therapy is indicated.