Mg Of Amiodarone Research Articles

Prophylactic amiodarone versus lidocaine for prevention of reperfusion ventricular fibrillation after release of aortic cross-clamp

Ventricular fibrillation is common after aortic cross-clamp release in patients undergoing open-heart surgeries. The aim of the study was to evaluate the efficacy of the prophylactic administration of 150 mg amiodarone by way of the pump 2 min before release of aortic cross-clamp in preventing ventricular fibrillation. The present study is a prospective, randomized, controlled and blinded study performed at a teaching university hospital where 120 patients undergoing coronary bypass graft surgery were randomly assigned to three groups. Each group received either 150 mg of amiodarone or 100 mg lidocaine or isotonic saline by way of pump 2 min before release of the aortic cross-clamp. The frequency of occurrence of ventricular fibrillation and the subsequent required defibrillation counter shocks were determined in all groups. The frequency of occurrence of ventricular fibrillation was significantly higher in both the amiodarone (48%) and the control group (45%) as compared with the lidocaine group (20%) with no statistically significant difference between the amiodarone and the control groups. Furthermore, when ventricular fibrillation occurred, the percentage of patients requiring defibrillation counter shocks was significantly higher in both the amiodarone (58%) and control (61%) groups as compared with the lidocaine group (13%) with no difference between the amiodarone and the control groups, despite a significant decrease in the defibrillation counter shocks energy requirements in the amiodarone group. The present study showed no difference between amiodarone (150 mg) and placebo in preventing ventricular fibrillation after release of aortic cross-clamp. In addition, the use of lidocaine was able to reduce the incidence of ventricular fibrillation as compared with both amiodarone and placebo.

Amiodarone for the Prevention of Reperfusion Ventricular Fibrillation

The purpose of this study was to evaluate the efficacy of prophylactic single-dose amiodarone administered through the pump circuit before releasing the aortic cross-clamp (ACC) in preventing the occurrence of reperfusion ventricular fibrillation (RVF). A prospective, randomized double-blind, placebo-controlled efficacy study. A tertiary level teaching hospital. Seventeen patients received 150 mg of amiodarone in 10 mL of normal saline by way of the pump 3 minutes before releasing the ACC, and a control group of 17 patients received 10 mL of normal saline. The primary outcome of the study was the incidence of ventricular fibrillation requiring defibrillation during the 30-minute period after myocardial reperfusion. A large decrease in RVF (65% to 18%) was observed in the amiodarone-treated group with the number needed to treat only 2.1.The myocardial performance in terms of cardiac output was better in the amiodarone group; this could be attributed to the lower incidence of RVF and subsequent direct current shock therapy. The observations showed that single-dose prophylactic amiodarone administered through the pump circuit 3 minutes before ACC release was an effective therapy to reduce the incidence of post-ACC release ventricular arrhythmias.

The unmasking of a Brugada phenotype after pulmonary resection: A case report and implications for postoperative management

CLINICAL SUMMARY A 78-year-old white man was diagnosed with non–small cell lung cancer by transthoracic fine-needle aspirate. His medical history included type I diabetes mellitus, hypothyroidism, emphysema, and a distant history of cholangiocarcinoma treated with surgery, chemotherapy, and radiation. He had a 30-pack-year smoking history and stopped using tobacco 20 years ago. Staging evaluation, including magnetic resonance imaging of the brain, positron emission tomography-computed tomography scan, flexible bronchoscopy, and mediastinoscopy, revealed node-negative poorly differentiated stage IA non–small cell lung cancer. The patient enrolled in a clinical trial studying the efficacy of pre-resection administration of amiodarone in reducing postoperative atrial dysrhythmias. As part of the study protocol 7 days before his operation, the patient commenced taking 200 mg of amiodarone orally twice per day. He underwent an uncomplicated left thoracotomy and left lower lobectomy, and continued to receive oral amiodarone the day after his operation. Pain control was achieved using epidural anesthesia, with the catheter positioned at the T4 level. The epidural solution consisted of 0.1% bupivacaine and 10 mg/mL of hydromorphone, infused from 4 to 6 mL/h. The patient’s postoperative course was complicated by oliguria, azotemia, hyperglycemia, and hyperkalemia. Blood urea nitrogen and serum creatinine levels increased to 39 and 1.8 mg/dL from baseline values of 22 and 0.9 mg/dL, respectively. Peak serum potassium level was measured at 6.1 mg/dL. On discovery of hyperkalemia, an electrocardiogram was obtained to assess for electrolyte-related changes. ‘‘Cove’’-type ST elevations and a right bundle branch block were noted in precordial leads V1 and V2. Known as the Brugada syndrome pattern, these findings were vastly different from the patient’s preoperative electrocardiogram (Figures 1 and 2). A medication review was undertaken. Any medications known to block cardiac sodium channels were identified and discontinued. The hyperkalemia was corrected. Serial cardiac enzymes failed to reveal an acute ischemic event. A transthoracic echocardiogram showed a mildly dilated left atrium, normal regional left ventricular wall motion, a left ventricular ejection fraction of more than 55%, and trivial mitral regurgitation. Compared with the patient’s preoperative study, the echocardiogram was unchanged. Serial electrocardiograms were obtained, and 48 hours after the Brugada pattern was noted, the electrocardiogram normalized. Throughout the period of electrocardiographic abnormality, our patient remained asymptomatic. He denied any history of syncope or near-syncope. His family history was negative for sudden cardiac death. He recovered from surgery and was discharged on the sixth postoperative day.

Administração inadvertida de 4 mg de morfina por via subaracnóidea: relato de caso

The subarachnoid administration of morphine is a well-established anesthetic technique of postoperative analgesia due to its efficacy safety and low cost. The objective of this paper was to report the accidental subarachnoid administration of 4 mg of morphine complicated by atrial fibrillation after administration of naloxone. A 45-year old male patient with 75 kg, 1.72 m, physical status ASA II, hypertensive, was scheduled for reconstruction of the anterior cruciate ligament of the left knee. After spinal anesthesia, it was noticed that the vial of morphine had been changed resulting in the accidental subarachnoid administration of 4 mg of morphine (0.4 mL of the 10 mg vial). Respiratory rate varied from 12 to 16 bpm and the patient remained hemodynamically stable without intraoperative complaints. Thirty minutes after admission to the post-anesthesia recovery unit the patient developed vomiting and diaphoresis being treated with 0.4 mg of naloxone followed by continuous infusion of 0.2 mg x (-1) until the symptoms had subsided. Continuous naloxone infusion was maintained in the Intensive Care Unit (ICU), where blood pressure, heart rate, respiratory rate and oxygen saturation were monitored as well as the presence of nausea, pruritus, vomiting, sedation, pain and urinary retention. Two hours after arriving at the ICU the patient developed acute atrial fibrillation without hemodynamic instability. Sinus rhythm was reestablished after the administration of 150 mg of amiodarone and discontinuation of the naloxone infusion. During the following 18 hours the patient remained hemodynamically stable and did not experience any other intercurrence until his discharge from the hospital. The present report is an alert for the risk of inadvertently switching of drugs during anesthesia, stressing the importance of referring patients being treated for opiate overdose to the ICU, due to the potential adverse reactions.

Practical Regimen for Amiodarone Use in Preventing Postoperative Atrial Fibrillation

Postoperative atrial fibrillation occurs in 5% to 65% of patients undergoing cardiac surgery. Although postoperative atrial fibrillation is often regarded as a temporary, benign, operation-related problem, it is associated with a twofold to threefold increase in risk of adverse events, including permanent or transient stroke, acute myocardial infarction, and death. This randomized, controlled, double-blinded trial included 250 eligible consecutively enrolled patients undergoing coronary artery bypass grafting (CABG). They received 300 mg of amiodarone/placebo administered intravenously over 20 minutes on the first postoperative day and an oral dose of 600 mg of amiodarone or placebo twice daily for the first 5 postoperative days. The patients in amiodarone prophylaxis experienced a reduction in risk of atrial fibrillation of 14% (95% confidence interval [CI], 5.0% to 24%), with the number needed to treat at 6.9 (95% CI, 4.2 to 20), and the results for symptomatic atrial fibrillation showed a risk reduction of 18% (95% CI, 9.4% to 26), with the number needed to treat at 5.7 (95% CI, 3.9 to 11). Of the patients who developed atrial fibrillation in the placebo group, 84% experienced a symptomatic attack versus only 43% in the amiodarone group. Postoperative prophylaxis with a high dose of oral amiodarone after an intravenous bolus infusion is a safe, practical, feasible, and effective regimen for CABG patients. It significantly diminishes the occurrence of postoperative atrial fibrillation.

Alta dose de amiodarona em curto período reduz incidência de fibrilação atrial e flutter atrial no pós-operatório de cirurgia de revascularização miocárdica

To investigate whether oral amiodarone administered before surgery for a short period in high dose would reduce the incidence of postoperative atrial fibrillation or atrial flutter and reduces the length of hospital stay. In the double-blind, randomized study, 93 patients were given either oral amiodarone (46 patients) or placebo (47 patients). Therapy consisted of 600 mg of amiodarone three times a day, started at minimum 30 hours and at maximum 56 hours before surgery. Postoperative atrial fibrillation or atrial flutter occurred in 8 of 46 patients in the amiodarone group (17.4%) and 19 of the 47 patients in the placebo group (40.4%) (p=0.027). The mean dose of amiodarone was 2.8 g. Patients in the amiodarone group were hospitalized for 8.9+/-3.1 days and patients in the placebo group were hospitalized for 11.4+/-8.7 days (p=0.07). The hospital length were significantly prolonged in patients who developed atrial arrhythmias after surgery, despite the treatment received.(p<0.001). This new alternative way of using amiodarone in high dose and in a short-term period before surgery reduce the incidence of postoperative atrial fibrillation or atrial flutter in coronary artery bypass graft surgery.

Fatal case of amiodarone-induced acute respiratory distress syndrome in a patient with severe left ventricular dysfunction due to extensive anterior acute myocardial infarction.

We here report a case of 71-year-old man with acute extensive anterior myocardial infarction, who was complicated with ventricular tachycardia (VT) even after successful percutaneous coronary intervention. As intravenous administration of nifekalant terminated VT, we started oral administration of amiodarone (day 1). We gave 400 mg of amiodarone a day for the first week and 200 mg a day from the second week. The patient was stable with normoxia by day 20, in spite of pulmonary congestion-like infiltrates on chest X-ray. On day 21, he was complicated with acute respiratory distress syndrome. Immediate discontinuance of amiodarone and high-dose pulse glucocorticoid therapy with intubation slightly improved the infiltrations on chest X-ray. However, glucocorticoid therapy induced hyperglycemia with an increase in plasma osmolality, complicated with hypoalbuminemia, and gastrointestinal bleeding. Despite treatment with a large amount of saline, high-doses of catecholamines, and blood transfusion, the patient died on day 28. It is sometimes difficult to diagnose congestive heart failure or amiodarone-induced pulmonary infiltrates in patients with severe left ventricular dysfunction.

Effects of amiodarone and thoracic epidural analgesia on atrial fibrillation after coronary artery bypass grafting

Objective : This study was designed to assess the effects of a perioperative dosing regimen of amiodarone administration, high thoracic epidural anesthesia (TEA), or a combination of the 2 regimens on atrial fibrillation (AF) after coronary artery bypass grafting (CABG). Design and Setting : The study was prospective, controlled, and randomized and was performed in a tertiary health care center associated with a university. Participants : One hundred sixty-three patients scheduled for coronary artery bypass graft surgery. Interventions : In this 2 × 2 factorial-designed study the patients were randomized to 1 of 4 regimens in which group E had perioperative TEA, group E+A had TEA and amiodarone, group A had amiodarone, and group C served as control. The epidural catheter was inserted at T1-3 the day before surgery. TEA groups received TEA for 96 hours. The amiodarone regimen consisted of a single loading dose of 1,800 mg of amiodarone orally. Intravenous infusion of amiodarone was started after induction of anesthesia and was administered at 900 mg over 24 hours for the subsequent 3 days. Measurements and Main Results : AF was documented using Holter monitoring. In group E 22 of 44 (50%), in group E+A 10 of 35 (28.6%), in group A 10 of 36 (27.8%), and in the control group 20 of 48 (41.7%) patients developed AF (odds ratio amiodarone/nonamiodarone 0.47 [0.24–0.90]; P = 0.02). Conclusions : The perioperative amiodarone regimen used in this study was effective in reducing the incidence of AF after CABG while TEA was not.

A useless error?

The diagnostic workup for syncope in a patient who does not have an obvious reason to faint is often frustrating. Adherence to published guidelines concerning diagnosis and treatment of syncope may also often be unhelpful. My patient was referred because he had had three or four syncopes within the previous 2 months. His primary physician had found a nine-beat, non-sustained ventricular tachycardia (VT) on Holter electrocardiogram (ECG), and had prescribed 300 mg of amiodarone each day. The patient was referred to me for further diagnostic testing.

Comparison of amiodarone versus ibutilide for the prevention of immediate recurrences of atrial fibrillation during pulmonary vein isolation

During segmental ostial ablation for pulmonary vein isolation, pulmonary vein potentials are easily identified during sinus rhythm or left atrial pacing. Therefore, maintenance of atrial fibrillation (AF) during the procedure is desirable. However, cardioversion is occasionally followed by an immediate recurrence of AF. This study compared the efficacy of ibutilide and amiodarone in preventing immediate recurrences of AF in patients who underwent pulmonary vein isolation. The subjects of this study were 25 patients (mean age 56 ± 10 years) who underwent pulmonary vein isolation for AF who had an immediate recurrence of AF within 60 seconds after 2 transthoracic cardioversions. The patients were randomized to receive an infusion of either 300 mg of amiodarone over 10 minutes or 1 mg of ibutilide over 5 minutes. Cardioversion was repeated 15 minutes after the drug infusion. If immediate recurrences of AF occurred 2 more times, the alternative study drug was administered, and cardioversion was repeated. Immediate recurrences of AF were suppressed by amiodarone in 8 of 10 patients (80%), and by ibutilide in 9 of 15 patients (60%, p = 0.4). After crossover, immediate recurrence of AF was suppressed in 2 of 6 patients (33%) by amiodarone, and in 1 of 2 patients (50%) by ibutilide (p = 0.6). Ibutilide and amiodarone, when used alone or in combination, prevented immediate recurrences of AF in 20 of 25 patients (80%). There were no adverse drug effects. Ibutilide and amiodarone were equally effective in suppressing immediate recurrences of AF. Overall, immediate recurrences of AF can be prevented by amiodarone and/or ibutilide in 80% of patients.

Amiodarone for atrial fibrillation during off-pump coronary artery bypass graft surgery

Case 1 An 81-year-old woman presented for OP-CAB surgery with severe 3-vessel coronary artery disease. Significant components of her past medical history included a diagnosis of mitral valve prolapse and 3 separate transient ischemic attacks that were believed to be related to the mitral valve dysfunction. Preoperative medications included metoprolol and enteric-coated acetylsalicylic acid. An intraoperative transesophageal echocardiogram revealed a left ventricular ejection fraction of 35% and moderate left atrial enlargement without evidence of thrombus. Shortly after opening the pericardium, the patient was noted to convert from sinus rhythm to atrial fibrillation. With this change in rhythm, the ventricular rate increased from 80 to 120 beats/min, and systolic blood pressure decreased from 125 to 90 mmHg. Synchronized electrical cardioversion was attempted 4 times without effect. A loading dose of 300 mg of amiodarone (patient’s weight, 49 kg) was administered intravenously over 30 minutes while the proximal vein graft anastomoses to the aorta were completed. During the amiodarone infusion, the patient’s ventricular rate slowed to 70 beats/min, and phenylephrine was administered for a mild transient decrease in blood pressure. After completion of the loading dose, the patient was electrically cardioverted to sinus rhythm on the first attempt. The patient then underwent 4 distal coronary artery anastomoses without further incident. An amiodarone infusion was initiated after the loading dose and continued for 24 hours. The patient’s recovery proceeded uneventfully, and no further arrhythmias had occurred at the time of discharge on postoperative day 7. Case 2 A 78-year-old man presented for OP-CAB surgery for treatment of 3-vessel coronary artery disease. The patient’s past medical history included non‐insulin-dependent diabetes, a remote stroke from which he had recovered, and cholelithiasis. Preoperative medications included glipizide, acetylsalicylic acid, atorvastatin, and amlodipine. A preoperative transthoracic echocardiogram was essentially normal with the exception of impaired left ventricular relaxation. The patient’s hospital course was remarkable for the development of acute cholecystitis requiring percutaneous cholecystostomy 7 days before OP-CAB surgery. At that time, the patient was noted to suffer a self-limited episode of atrial fibrillation lasting 1 hour. Atrial fibrillation recurred intraoperatively during inspection of the epicardial vessels. A loading dose of 450 mg of amiodarone (patient’s weight, 98 kg) was administered intravenously over 30 minutes without hemodynamic effect. After amiodarone loading, the patient was successfully electrically cardioverted to sinus rhythm. A 3-vessel OP-CAB procedure was completed, and the patient was transferred to the intensive care unit in stable condition. No further amiodarone was administered after the loading dose, and no further episodes of atrial fibrillation were noted during the patient’s hospital stay. An open cholecystectomy was performed on postoperative day 15, and the patient was discharged to a rehabilitation facility 21 days after his cardiac surgery. Case 3

Single-day loading dose of oral amiodarone for the prevention of new-onset atrial fibrillation after coronary artery bypass surgery

Background Various regimens have been proposed for the prevention of postoperative atrial fibrillation, including the use of intravenous and oral amiodarone. The purpose of this study was to determine the effectiveness of a single-day loading dose of oral amiodarone in prophylaxis of atrial fibrillation during the 7 days after coronary artery bypass surgery. Methods We conducted a double-blind, randomized, placebo-controlled study encompassing 315 consecutive patients who underwent coronary artery bypass surgery. They received either amiodarone (159 patients) or placebo (156 patients). Therapy consisted of a single oral loading dose of 1200 mg of amiodarone 1 day before surgery, followed by the maintenance dose of 200 mg daily during the next 7 days. Only episodes of atrial fibrillation lasting more than 1 hour or associated with hemodynamic compromise were taken into consideration. Results Overall, the incidence of atrial fibrillation was similar in patients who received amiodarone (31/159, 19.5%) and placebo (33/156, 21.2%) (P =.78). However, amiodarone reduced the incidence of atrial fibrillation in elderly patients (age ≥60 years): it occurred in 20 of 75 (26.7%) patients on amiodarone and in 28 of 65 (43.1%) patients in the placebo group (P =.05). There were no differences between the study groups regarding the postoperative intrahospital morbidity and mortality and the duration of hospital stay. Conclusions A single-day loading dose of oral amiodarone (1200 mg) does not prevent postoperative atrial fibrillation in a general population of patients undergoing coronary artery bypass surgery. However, it appears that this regimen reduces the occurrence of postoperative atrial fibrillation in elderly patients. (Am Heart J 2001;141:e8.)

Intravenous amiodarone decreases the duration of atrial fibrillation associated with acute myocardial infarction.

Atrial fibrillation (AF) is a fairly common complication of acute myocardial infarction (AMI). The aim of this study was to examine the safety and efficacy of intravenous amiodarone in converting AF associated with AMI. Seventy patients with AMI complicated with AF were prospectively divided into 3 groups: a) In group D (n = 26), 0.75 mg digoxin was administered intravenously and thereafter as needed, b) In group AM (n = 16), 300 mg of amiodarone was infused over 2 hours followed by 44 mg/hour for up to 60 hours or until sinus rhythm was restored, c) In group D + AM (n = 28), 0.75 mg of digoxin was administered (as in group D) for the initial 2 hours followed by amiodarone infusion as in group AM. Sinus rhythm was restored: a) by the end of the 2nd hour in 9/26 patients from group D, 4/16 from group AM, and 10/28 from group D + AM (p = NS), b) by the end of the 96th hour, in 18/26 patients from group D, and in all patients from group AM and groupd D + AM. The corresponding duration of AF was 51 +/- 34 hours, 17 +/- 15 hours and 9 +/- 13 hours, respectively (F = 15.4, p < 0.001). AF recurred in 9/26, 5/16 and 1/28 patients of groups D, AM and D + AM, respectively (p = 0.026). The required dosage of amiodarone was lower in the D + AM group than in the AM group (603 +/- 563 mg versus 1058 +/- 680 mg, p = 0.037). Intravenous amiodarone was well tolerated in patients with AMI complicated by AF and was effective in decreasing the duration of AF. However, the combination of amiodarone and digoxin was superior to amiodarone alone in restoring sinus rhythm faster, maintaining sinus rhythm longer, and allowing the use of a lower cumulative amount of amiodarone.

Preoperative Amiodarone as Prophylaxis Against Atrial Fibrillation After Heart Surgery

Background Atrial fibrillation occurs commonly after open-heart surgery and may delay hospital discharge. The purpose of this study was to assess the use of preoperative amiodarone as prophylaxis against atrial fibrillation after cardiac surgery. Methods In this double-blind, randomized study, 124 patients were given either oral amiodarone (64 patients) or placebo (60 patients) for a minimum of seven days before elective cardiac surgery. Therapy consisted of 600 mg of amiodarone per day for seven days, then 200 mg per day until the day of discharge from the hospital. The mean (±SD) preoperative total dose of amiodarone was 4.8±0.96 g over a period of 13 ± 7 days. Results Postoperative atrial fibrillation occurred in 16 of the 64 patients in the amiodarone group (25 percent) and 32 of the 60 patients in the placebo group (53 percent) (P = 0.003). Patients in the amiodarone group were hospitalized for significantly fewer days than were patients in the placebo group (6.5 ± 2.6 vs. 7.9 ± 4.3 days, P = 0.04). ...

Amiodarone and the Development of ARDS After Lung Surgery-To the Editor

Drs. Alves and van der Zeijden suggest that the reduction in a lung parenchyma may be a predisposing factor for the development of ARDS when a standard dose of 1,200 mg of amiodarone is used in patients after a pneumonectomy. We agree and made the same suggestion at the end of our article (Chest 1994; 105:1642-45).

Can amiodarone pulmonary toxicity be predicted in patients undergoing implantable cardioverter defibrillator implantation?

Implantable cardioverter defibrillator (ICD) implantation is rapidly becoming accepted as primary therapy for malignant ventricular arrhythmias. Many patients undergoing ICD implantation are on concomitant antiarrhythmic drugs to decrease shock frequency, slow tachycardia rate, and suppress supraventricular arrhythmias. Amiodarone is a potent antiarrhythmic agent that is also frequently used in the treatment of patients with refractory ventricular arrhythmias. Ten to forty percent of patients undergoing ICD implantation will also be taking amiodarone. It has been reported to cause pulmonary toxicity in about 5% of patients per year. Acute amiodarone toxicity presenting as adult respiratory distress syndrome has been reported much less frequently. Although perioperative morbidity due to amiodarone has been described, the risk, predictability, and consequences of acute pulmonary toxicity from amiodarone in patients undergoing ICD implantation have not been previously described. We reviewed the records of 99 consecutive patients undergoing ICD implantation at our institution from October 1987 to April 1992. Thirty-nine patients were taking 480 +/- 230 mg of amiodarone (median 400 mg, lower 20th percentile 400 mg, upper 80th percentile 800 mg) for 291 +/- 554 days prior to ICD implantation. Ten patients taking amiodarone developed acute pulmonary toxicity clinically manifesting as diffuse pulmonary infiltrates on chest radiography and adult respiratory distress syndrome with hypoxia (arterial pO2 < 60 mmHg) without evidence of pneumonia or elevated pulmonary capillary wedge pressure (PCW < or = 15 mmHg). Of the 60 patients not taking amiodarone none developed adult respiratory distress syndrome.(ABSTRACT TRUNCATED AT 250 WORDS)

Low-Dose Amiodarone for Maintenance of Sinus Rhythm After Cardioversion of Atrial Fibrillation or Flutter

To study efficacy and safety of low-dose amiodarone for maintenance of sinus rhythm after electrical cardioversion of atrial fibrillation or flutter. Nonrandomized trial; mean duration of follow-up, 20.7 months. Referral center; institutional practice; both hospitalized and ambulatory care. Eighty-nine consecutive patients having chronic atrial fibrillation or flutter and eligible for cardioversion. Patients had failed previous treatment aimed at maintaining sinus rhythm. During follow-up one patient was withdrawn because of side effects; all patients were available for follow-up. Before cardioversion, patients received 600 mg of amiodarone daily during a 4-week loading period. After conversion, the daily maintenance dose was 204 +/- 66 mg (mean +/- SD). Arrhythmia recurrence and adverse effects causing drug discontinuation. During loading, 15 patients (16%) converted, and after electrical cardioconversion, 90% of all patients had sinus rhythm. Actuarially, 53% of these patients were still in sinus rhythm after 3 years. In patients with compromised left ventricular function, 93% maintained sinus rhythm after 6 months. One patient died due to congestive heart failure. Intolerable side effects occurred in one patient. No proarrhythmia was observed. Logistic regression analysis revealed that amiodarone was ineffective in patients with mitral stenosis or chronic arrhythmia. Low-dose amiodarone is effective for maintaining sinus rhythm in patients with difficult to treat chronic atrial fibrillation or flutter and is associated with a low incidence of serious side effects.

Low-dose amiodarone for maintenance of sinus rhythm after cardioversion of atrial fibrillation or flutter

<h3>Objective.</h3> —To study efficacy and safety of low-dose amiodarone for maintenance of sinus rhythm after electrical cardioversion of atrial fibrillation or flutter. <h3>Design.</h3> —Nonrandomized trial; mean duration of follow-up, 20.7 months. <h3>Setting.</h3> —Referral center; institutional practice; both hospitalized and ambulatory care. <h3>Patients.</h3> —Eighty-nine consecutive patients having chronic atrial fibrillation or flutter and eligible for cardioversion. Patients had failed previous treatment aimed at maintaining sinus rhythm. During follow-up one patient was withdrawn because of side effects; all patients were available for follow-up. <h3>Intervention.</h3> —Before cardioversion, patients received 600 mg of amiodarone daily during a 4-week loading period. After conversion, the daily maintenance dose was 204±66 mg (mean±SD). <h3>Main Outcome Measures.</h3> —Arrhythmia recurrence and adverse effects causing drug discontinuation. <h3>Results.</h3> —During loading, 15 patients (16%) converted, and after electrical cardioconversion, 90% of all patients had sinus rhythm. Actuarially, 53% of these patients were still in sinus rhythm after 3 years. In patients with compromised left ventricular function, 93% maintained sinus rhythm after 6 months. One patient died due to congestive heart failure. Intolerable side effects occurred in one patient. No proarrhythmia was observed. Logistic regression analysis revealed that amiodarone was ineffective in patients with mitral stenosis or chronic arrhythmia. <h3>Conclusions.</h3> —Low-dose amiodarone is effective for maintaining sinus rhythm in patients with difficult to treat chronic atrial fibrillation or flutter and is associated with a low incidence of serious side effects. (<i>JAMA</i>. 1992;267:3289-3293)

Evaluation of amiodarone therapy in the treatment of drug-resistant cardiac arrhythmias: long term follow-up.

The clinical efficacy of amiodarone in the management of patients with complex cardiac arrhythmias refractory to therapy with two or more conventional or other investigational anti-arrhythmic agents was studied by long-term follow-up of patients who had received the drug for a period of at least three months. A total of 181 patients, classified into four groups (Group 1--supraventricular arrhythmias, n = 42; Group 2--frequent VPBs, n = 46; Group 3--nonsustained V-tach, n = 16; and Group 4--sustained V-tach, n = 77) received a daily maintenance dose of 200-800 mg of Amiodarone for a period of up to 30 months. There were a total of 26 deaths (14%). Ten of these were classified as probable arrhythmic deaths; however, all had either good or excellent response to therapy over a mean follow-up period of 14.9 months prior to death. The drug had to be permanently discontinued due to side effects only in three patients and in the majority of patients with side effects symptoms could be alleviated with adjustment of dosage, thyroid replacement therapy or transient cessation of therapy. We conclude that amiodarone is highly effective in the management of high-risk patients with complex refractory cardiac arrhythmias and that close monitoring and prompt recognition of side effects and appropriate adjustment of dosage or institution of supplemental or replacement therapy (in less than 5% of patients) will allow continuation of amiodarone. The benefit of suppression of symptomatic arrhythmias and the potential of prevention of sudden death, far outweighs the incidence of severe side effects.

Intravenous amiodarone in the acute treatment of recurrent symptomatic ventricular tachycardia

Fifteen patients aged 59.3 +/- 11.5 years (mean +/- standard deviation [SD]) had recurrent symptomatic ventricular tachycardia (VT) refractory to at least 2 conventional antiarrhythmic drugs. All patients had organic heart disease; 4 had an acute myocardial infarction. The mean ejection fraction was 0.30 +/- 0.09. TWelve patients had overt congestive heart failure. Five had bundle branch block. Before treatment with intravenous amiodarone, the patients had had 6 to 40 episodes of symptomatic VT over 1 to 8 days of hospitalization. All patients received an initial bolus of 5 mg of amiodarone/kg over 15 minutes. Seven patients also received a continuous infusion of 600 to 1,000 mg of amiodarone over 12 to 24 hours. Additional doses depended on the patients' clinical responses. In 11 of 15 patients, antiarrhythmic drugs that had failed to suppress VT were continued during administration of amiodarone. In 12 of 15 patients acute control of VT was obtained with intravenous administration of amiodarone either alone or in combination with previously ineffective drugs. Three patients continued to have frequent episodes of VT while being treated with intravenous amiodarone. Mobitz type I atrioventricular block developed in 1 patient. No patient had high degree atrioventricular block, symptomatic hypotension, or a clinically apparent worsening of congestive heart failure. The use of intravenous amiodarone represents a significant advance in the acute treatment of frequent life-threatening VT refractory to other drugs. With appropriate monitoring, it can be used safely in patients with congestive heart failure, bundle branch block, or acute myocardial infarction.