Intravenous amiodarone is safe and seems to be effective in termination of paroxysmal supraventricular tachyarrhythmias

Background: Paroxysmal atrial fibrillation (PAF) and paroxysmal supraventricular tachycardia (PSVT) leading to hemodynamic compromise are among the most common reasons for admission to the coronary care unit (CCU) and need prompt and efficient therapy. Direct current cardioversion is the therapy of choice, but if found contraindicated or unavailable some antiarrhythmie agents are usually given to restore sinus rhythm. Many of these drugs have obvious limitations, especially in patients with acute myocardial infarction and/or heart failure. Hypothesis: The aim of the present study was to assess the safety and efficacy of intravenous amiodarone in the acute termination of PAF or PSVT refractory to other antiarrhythmie agents in a large group of patients consecutively admitted to our CCU. Methods: In the present study, we evaluated the safety and efficacy of amiodarone given intravenously in 142 consecutive patients with PAF or PSVT lasting < 24 h. In 37% of patients no evidence of underlying heart disease which may have caused arrhythmias were defined. A median of two other antiarrhythmic agents given prior to the first amiodarone injection had been ineffective. Results: Sinus rhythm was restored in 91 patients (64%) (65% in the PAF group and 61% in the PSVT group). The mean time to rhythm conversion was 5.5 ± 6.1 h for patients with PAF and 1.2 ± 1.2 h for patients with PSVT. The mean dose of amiodarone administered up to conversion was 340 ± 220 mg for PAF and 220 ± 105 mg for PSVT. Except for transient first-degree atrioventricular block in two patients, no adverse effects possibly related to amiodarone were observed (including proarrhythmia and incidence or aggravation of heart failure symptoms). Conclusion: Amiodarone given intravenously for acute termination of supraventricular tachyarrhythmias is completely safe and seems effective. The results of this study, which is the largest ever made, indicate a need of randomized, controlled trials for the ultimate assessment of the efficacy of amiodarone in this clinical setting.     

Multicentre randomized trial of sotalol vs amiodarone for chronic malignant ventricular tachyarrhythmias

Sotalol was compared with amiodarone in this open randomizedmulticentre study of patients with ventricular tachycardia orfibrillation not associated with acute myocardial infarctionrefractory to or intolerant of Class I drugs. 16 of 30 patientstreated with amiodarone completed 12 months on therapy, fivewere withdrawn because of recurrent ventricular tachycardiaand nine because of presumed adverse drug reactions, complianceproblems or protocol violation. Four of those who were withdrawndied within 12 months. Sixteen of 29 patients completed 12 months on sotalol, one waswithdrawn because of ventricular tachycardia and nine becauseof presumed adverse drug reactions, poor compliance or the needfor coronary artery surgery. Three died on treatment and twoafter withdrawal but within 12 months of entering the study. When the results are analysed by intention to treat there wasno significant difference in antiarrhythmic efficacy or in theincidence of side-effects severe enough to warrant withdrawalfrom the trial. There was an increase in left ventricular ejectionfraction in those treated with sotalol, which, because of itspharmacokine-tics, is an attractive alternative to amiodaronefor patients with malignant ventricular arrhythmias who cantolerate ß-adrenergic blockade.     

Efficacy of phenytoin in suppressing inducible ventricular tachyarrhythmias

Summary We examined the efficacy of phenytoin in 69 of 87 consecutive patients undergoing serial electrophysiologic studies for inducible sustained ventricular tachycardia or fibrillation (VT/VF). In general, during the initial session lidocaine and procainamide were tested immediately after baseline electrophysiologic evaluation, followed by phenytoin and quinidine during the next two sessions, and then by additional drugs as needed. Once a successful drug was identified, all testing was stopped. Drugs that had failed in prior empiric trials were not tested. Twenty-five of the 87 patients (28.7%) had success in 258 serial drug tests. Sixty-nine patients were tested on phenytoin (mean serum level 13.4 ± 5.0 mg/L), 52 after oral loading, and 17 after intravenous loading; the remaining 18 had either had prior successful testing with other drugs (9 patients) or had prior empiric failures with phenytoin (9 patients). Nine of the 69 phenytoin trials were successful (13.0%), compared to 8 of 57 trials (14.0%) with procainamide, 4 of 37 trials (10.8%) with quinidine, and 0 of 41 trials (0%) with lidocaine. All nine patients who had successful phenytoin trials tolerated chronic doses adequate to maintain serum phenytoin levels equivalent to those measured during successful drug testing.For the 25 patients with successful drug trials, the mean follow-up was 14.5 ± 9.8 months, and the actuarial incidence or recurrent VT/VF was 7 ± 5% at 12 months. For the nine patients who had success with phenytoin the mean follow-up was 18.4 ± 11.7 months, and the 12-month actuarial recurrence was 0%. Phenytoin is a well tolerated drug whose efficacy appears similar to most standard antiarrhythmic agents. If our results are confirmed in a larger, randomized study, routine testing with phenytoin should be considered.     

Efficacy and safety of short intravenous amiodarone in supraventricular tachyarrhythmias.

The safety and efficacy of short intravenous therapy with amiodarone were evaluated in 44 patients (24 males, 20 females), aged 21-84 years, with supraventricular tachyarrhythmias newly arisen in less than 24 hours. The study group consisted of 15 patients with paroxysmal supraventricular tachycardia, 8 patients with atrial flutter and 21 patients with atrial fibrillation. They were treated with a single infusion of amiodarone up to 2 hours after the restoration of a stable sinus rhythm, or up to a maximum dose of 2400 mg in 24 hours. Our study shows that 88.6% of all supraventricular tachyarrhythmias reverts to sinus rhythm in less than 24 hours: 100% of paroxysmal supraventricular tachycardia, 75% of atrial flutter, and 85.7% of atrial fibrillation. Intravenously administered amiodarone proves to take effect rapidly (0.5 to 22 hours). The plasma amiodarone concentrations at sinus rhythm restoration showed a wide range (405-3800 ng/ml). Piecewise analysis suggested that the probability of sinus rhythm was 14.4-fold greater in paroxysmal supraventricular tachycardia. No linear statistical relationship was detectable between the log-dose-body mass index and log-QTc. Total amiodarone dose and left atrial volume are inversely correlated with a statistically significant difference. The toxicity in our short intravenous course with amiodarone was not relevant. We conclude that short high-dose intravenous amiodarone shows efficacy and safety in all newly occurring supraventricular tachyarrhythmias.     

Risk stratification and prognosis of patients treated with amiodarone for malignant ventricular tachyarrhythmias after myocardial infarction

Summary Seventy-seven consecutive patients (mean age 62 years) with episodes of sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) after acute myocardial infarction (AMI) were evaluated to assess the long-term efficacy of first-line amiodarone treatment and to identify clinical and laboratory factors associated with a high risk of death or arrhythmia recurrence. The presenting arrhythmia was VT in 41 cases (53%) and VF in 36 (47%). VT or VF occurred between the 4th and 90th day after AMI in 45 cases (58%) and later (more than 90 days) in the remaining 32 (42%). The mean number of arrhythmic episodes was 4.2. Forty patients (52%) were in New York Heart Association (NYHA) class I or II, and 37 (48%) were in class III or IV. Mean left ventricular ejection fraction was 32%; ventricular aneurysm was present in 41 subjects. Most patients had multivessel coronary artery disease. Amiodarone was administered as a first-choice drug in all patients, in combination with other antiarrhythmic drugs in 14. By ventricular stimulation after loading doses of amiodarone, sustained VT was inducible in 46 (62%) and noninducible in 28 (38%). During a mean follow-up of 28 months the incidence of cardiac mortality at 1, 3, and 5 years was 21%, 37%, and 47%; of sudden death was 7%, 19%, and 23%; of nonfatal VT recurrence was 13%, 13%, and 24%, respectively. The overall incidence of amiodarone side effects was 35%. Factors independently associated with mortality for all causes and cardiac mortality included NYHA class III or IV (p<0,01), ejection fraction -35% (p<0,01), and age -65 years (p=0,03). History of cardiac arrest was a weak predictor only by univariate analysis (p=0.05). No single variable was consistently related to an increased risk of sudden death and nonfatal VT recurrence, not even inducibility of sustained VT during electropharmacologic studies (18% of incidence in responders and 30% in nonresponders, p = ns). In this study, amiodarone treatment of patients with life-threatening ventricular tachyarrhythmias after myocardial infarction confirmed its beneficial, but not uniform, efficacy. Severe left ventricular dysfunction, age, and, less significantly, history of cardiac arrest, were independent predictors of death. Identification of patients at high risk of arrhythmia recurrence and sudden death remains undefined during amiodarone treatment.     

Intravenous cibenzoline in the management of acute supraventricular tachyarrhythmias

Summary Intravenous cibenzoline was evaluated in 37 patients with acute supraventricular tachyarrhytymias 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. In conclusion, intravenous cibenzoline may be useful in selected patients with supraventricular tachyarrhythmias. Careful monitoring is recommended during therapy in view of the possible occurrence of 1:1 atrial flutter.     

Efficacy and safety of intravenous amiodarone in acute refractory arrhythmias

Few data are available on intravenous amiodarone therapy in refractory arrhythmias. This retrospective study in 50 patients (14 with supraventricular and 36 with ventricular tachyarrhythmias) revealed a favorable effect of intravenous amiodarone in the treatment of life-threatening arrhythmias with an overall success rate of 76%. In the subgroup of patients with ventricular fibrillation and concomitant severe congestive heart failure success rate was low (25%, 2/8), whereas effectiveness in patients with ventricular tachycardias was high (greater than 90%) and proved to be independent of left ventricular function. If patients with recurrent ventricular fibrillation were excluded from the analysis, successful treatment with intravenous amiodarone was achieved in 90%, even in those patients with severely compromised myocardium.     

胺碘酮治疗急性冠脉综合征伴急性心力衰竭的室上性心动过速11例分析

目的评价胺碘酮治疗急性冠状动脉综合征(acute coronary syndrome,ACS)伴急性心力衰竭(acute heart failure,AHF)的室上性心动过速(supraventricular tachycardia,SVT)的临床疗效。方法回顾性分析接受胺碘酮治疗的11例伴SVT的ACS合并AHF患者的临床资料。结果在常规治疗无效时,对11例患者进行静脉应用胺碘酮治疗,其中9例(81.8%)迅速好转并顺利出院,1例死于心源性休克,另有1例需电击复律。结论对于伴SVT的AHF患者,要考虑ACS的可能;使用胺碘酮治疗安全有效。     

The effect of chronic atrial overdrive suppression pacing on the incidence of supraventricular tachyarrhythmias.

Chronic overdrive suppression pacing has been suggested as an effective adjunctive method for reducing the incidence of cardiac tachyarrhythmias. Documentation of effectiveness during prolonged monitoring is lacking, however. To assess more accurately the long-term utility of this treatment modality for medically refractory supraventricular tachyarrhythmias (SVTs), 10 patients with atrially implanted Intermedics Intertach pacemakers were randomly assigned to either a low or a high bradycardia (back-up) pacing rate. SVT counts were performed during matching follow-up periods both at the initial rate and after rate crossover. The primary antitachycardia modality of this pacemaker (P mod) provides burst pacing to terminate tachycardia episodes, and P mod counters were utilized to quantitate SVT episodes. Tachycardia termination algorithms were programmed to "no restart" and were not changed during the study. The P mod use counter, therefore, reflected the number of discrete episodes of SVTs. Pacemaker implantation diagnoses include atrial flutter, concealed bypass tract, AV nodal reentry, intraatrial reentry, and Wolff-Parkinson-White associated tachycardia. Patient age was 59 +/- 18 yrs. The average pacemaker back-up low rate was 45.7 +/- 4 versus a back-up high rate of 85.1 +/- 2 beats/min. Follow-up was for 57.4 days +/- 33 days at the low rate and 57.3 days +/- 34 days at the high rate (r = 0.99). There was no difference in SVT incidence with a P mod usage of 98.4 +/- 106 at the low rate and 100.8 +/- 94 at the high rate (p = NS). In this blinded, randomized cross-over trial, chronic atrial overdrive suppression pacing did not reduce the overall incidence of SVT episodes during prolonged monitoring.     

胺碘酮联合盐酸艾司洛尔救治心室电风暴的临床分析简

目的 探讨胺碘酮联合盐酸艾司洛尔治疗心室电风暴的疗效,总结治疗经验.方法 回顾性分析绍兴市人民医院近5年来心室电风暴（VES）患者的临床资料,入选患者均符合心室电风暴诊断标准,心室电风暴定义为24 h内自发≥2次的伴血流动力学不稳定的室性心动过速和（或）心室颤动,间隔窦性心律,通常需要电转复和电除颤紧急治疗的临床综合征.所有患者均予以电击转复或除颤,患者均应用胺碘酮抗心律失常,胺碘酮无效者加用盐酸艾司洛尔.结果 符合条件的患者共15例,其中冠状动脉粥样硬化性心脏病7例,扩张型心肌病3例,Brugada综合征1例,急性心肌炎1例,乌头碱中毒1例,特发性室性心动过速2例.所有患者均予以电击转复或除颤,平均电击4.5次.15例患者中5例经应用胺碘酮等治疗,心室电风暴得以控制,胺碘酮有效率33.3％.10例应用胺碘酮无效的患者,静脉应用盐酸艾司洛尔尚有7例有效,盐酸艾司洛尔对于胺碘酮无效的患者仍有70％的有效率.3例应用上述所有治疗措施无效,当天死亡.共抢救成功12例（80％）,死亡3例.存活的12例患者继续口服胺碘酮及美托洛尔维持治疗,其中3例患者植入植入型自动心律转复除颤器（ICD）.所有患者随访半年,猝死1例,其余11例未再复发心室电风暴.结论 胺碘酮联合盐酸艾司洛尔控制心室电风暴疗效显著,盐酸艾司洛尔值得进一步的探讨和应用.     

Amiodarone: an effective alternative for recalcitrant supraventricular and ventricular tachycardias

Amiodarone was used in the treatment of 21 patients with supraventricular or ventricular arrhythmias which were refractory to conventional antiarrhythmic drugs, individually or in combination. Six of seven patients with supraventricular arrhythmias and 12 of 14 with ventricular tachycardia were controlled with amiodarone. Although side effects were common, only one patient was removed from treatment due to pulmonary fibrosis. We conclude that amiodarone is an effective antiarrhythmic drug for refractory ventricular and supraventricular arrhythmias.     

A multicentre, randomized trial on the benefit/risk profile of amiodarone, flecainide and propafenone in patients with cardiac disease and complex ventricular arrhythmias

The long-term benefit/risk profiles of amiodarone, flecainideand propafenone were compared in 141 patients with complex ventriculararrhythmias and cardiac disease, in a trial designed to mimicthe clinical decision-making process. The patients were randomizedto various sequences of the three drugs, at two dose levelsandfollowedfor 2 years. Drug or doses were changed to deal withinsufficient reduction of arrhythmias at 24 h ECG or severeadverse drug reaction (ADR). At 2 years 18 patients haddied(9/18 suddenly), 19 had withdrawn because of major clinicalevents or severe ADR, 13 had dropped out, seven hadbeen non-respondersthroughout the entire sequence of drugs, whereas eight werenon-responders only at the last visit. Thus, 76 patients (54%)were responders after 2 years. Of these, 57 were respondersfor 2 years with thefirst drug. Median exposure time to amiodarone,518 days . patienr', was higher than for flecainide and propafenone,218 and 178, respectively, indicating better overall responseto amiodarone (P<001). A total of50 ADRs led to drug with-drawal,with cardiovascular ADR being less frequent (P<003) for amiodarone(2/11) than for flecainide (13/16) and propafenone (16/23).In conclusion, with sequences of amiodarone, flecainide andpropafenone, an overall response rate of 79% couldbe obtainedintheshort-term (7–28 days) and54% at 2years. Amiodaronehas a morefavourable therapeutic profile than flecainide andpropafenone in these patients, having less tendency to worsenheartfailure.     

Cigarette smoking and the risk of supraventricular and ventricular tachyarrhythmias in high-risk cardiac patients with implantable cardioverter defibrillators

Introduction: Nicotine elevates serum catecholamine concentration and is therefore potentially arrhythmogenic. However, the effect of cigarette smoking on arrhythmic risk in coronary heart disease patients is not well established.
Methods and Results: The risk of appropriate and inappropriate defibrillator therapy by smoking status was analyzed in 717 patients who received an implantable cardioverter defibrillator (ICD) in the Multicenter Automatic Defibrillator Implantation Trial-II. Compared with patients who had quit smoking before study entry (past smokers) and patients who had never smoked (never smokers), patients who continued smoking (current smokers) were significantly younger and generally had more favorable baseline clinical characteristics. Despite this, the adjusted hazard ratio (HR) for appropriate ICD therapy for fast ventricular tachycardia (at heart rates ≥180 b.p.m) or ventricular fibrillation was highest among current smokers  (HR = 2.11 [95% CI 1.11–3.99])  and intermediate among past smokers  (HR = 1.57 [95% CI 0.95–2.58])  , as compared with never smokers (P for trend = 0.02). Current smokers also exhibited a higher risk of inappropriate ICD shocks  (HR = 2.93 [95% CI 1.30–6.63])  than past  (HR = 1.91 [95% CI 0.97–3.77])  and never smokers (P for trend = 0.008).
Conclusions: In patients with ischemic left ventricular dysfunction, continued cigarette smoking is associated with a significant increase in the risk of life-threatening ventricular tachyarrhythmias and inappropriate ICD shocks induced by rapid supraventricular arrhythmias. Our findings stress the importance of complete smoking cessation in this high-risk population.     

Efficacy and toxicity of amiodarone for the treatment of supraventricular tachyarrhythmias

Amiodarone is an effective agent for all types of supraventricular tachyarrhythmias regardless of mechanism and may, in fact, control a high percentage of supraventricular tachyarrhythmias refractory to conventional antiarrhythmic agents. However, its toxicity should temper enthusiasm for the use of the medication in non-life-threatening arrhythmias. As always, when recommending specific therapies the potential benefit should be weighed in light of the related risk. In patients with life disordering, drug-refractory atrial fibrillation, it seems reasonable to attempt control with amiodarone. Likewise in patients with ectopic atrial tachycardias refractory to conventional agents, this seems reasonable as well. Other and better therapies are available for patients with life-threatening arrhythmias associated with the Wolff-Parkinson-White syndrome. While amiodarone is moderately effective in these patients, the advent of improved surgical techniques and the relatively low risk of an operation make surgery the treatment of choice. The role of IV amiodarone, acutely, in the treatment of supraventricular tachyarrhythmias remains to be defined.     

Efficacy of intravenous amiodarone in the management of paroxysmal or new atrial fibrillation with fast ventricular response

We tested the efficacy of intravenous amiodarone (5 mg/kg) in slowing ventricular response and/or restoring sinus rhythm in 26 patients with paroxysmal or new atrial fibrillation with fast ventricular response. There were 16 men and 10 women with ages ranging from 35 to 84 years, mean 63 years. Intravenous amiodarone initially slowed the ventricular response in all patients from 143 +/- 27 to 96 +/- 10 beats/min (P less than 0.001). Twelve patients (46%) reverted to sinus rhythm within the first 30 min (range 5 to 30 min, mean 14 +/- 9 min). One patient reverted to atrial flutter after 10 min and 40 min later to sinus rhythm. Six patients (23%) converted to sinus rhythm after 2 to 8 hr and in these 6 cases, the initial slowing in ventricular response obtained with amiodarone persisted until conversion. Seven patients (27%) did not convert to sinus rhythm following amiodarone administration and they required further medical therapy to slow the ventricular response and/or to convert to sinus rhythm. No serious side effects from drug administration were noted. Intravenous amiodarone appears as a highly effective medication in the conversion or control of new onset atrial fibrillation with fast ventricular response.     

Propafenone—Clinical Electrophysiology and Efficacy in Patients with Documented or Potentially Life-threatening Arrhythmias

Propafenone is a new antiarrhythmic agent that inhibits the fast sodium channel and decreases phase 0 of the cardiac action potential. Since it has relatively little effect on the action potential duration, it has been classified as a type IC agent. Propafenone prolongs electrocardiographic intervals including PR and QRS. In addition, atrial and ventricular refractory periods generally are lengthened. Initial reports suggest a favorable effect on suppressing conduction over accessory pathways. Propafenone has been shown to have effectiveness in suppressing life-threatening ventricular arrhythmias as well. Electrophysiological testing is useful, but data such as mode of induction and rate of induced tachycardia should be considered in addition to inducibility status.     

Sudden cardiac death while taking amiodarone therapy: the role of abnormal repolarization

Torsade depointes may occur as a complication of amiodaronetherapy. We report a patient receiving amiodarone who was resuscitatedfrom cardiovascular collapse and documented ventricular fibrillation.At subsequent electrophysiology study, while the patient wastaking amiodarone therapy, monophasic action potentials withearly after depolarisations were recorded which were not presentwhen the patient was restudied 6 weeks after discontinuationof amiodarone. Early after-depolarisations may be importantin the genesis of polymorphic ventricular tachycardia complicatingamiodarone therapy.     

Sudden cardiac death while taking amiodarone therapy: the role of abnormal repolarization.

Torsade de pointes may occur as a complication of amiodarone therapy. We report a patient receiving amiodarone who was resuscitated from cardiovascular collapse and documented ventricular fibrillation. At subsequent electrophysiology study, while the patient was taking amiodarone therapy, monophasic action potentials with early after depolarisations were recorded which were not present when the patient was restudied 6 weeks after discontinuation of amiodarone. Early after-depolarisations may be important in the genesis of polymorphic ventricular tachycardia complicating amiodarone therapy.     

Efficacy of encainide in supraventricular arrhythmias

This review summarizes the data from all the studies conducted in the United States and Europe that have evaluated the efficacy of encainide in patients with a variety of supraventricular arrhythmias. Using clinical criteria of efficacy, encainide was found to be effective or partially effective in 77% of patients evaluated by electrophysiologic means. Similar levels of efficacy were observed in patients with AV as well as AV nodal reentry arrhythmias. Patients with other forms of supraventricular arrhythmias in smaller series also experienced comparable degrees of efficacy. Encainide was discontinued because of intolerance by 8% of the patients in these studies: 6% because of side effects and 2% because of proarrhythmia.