Are patients receiving amiodarone at increased risk for cardiac operations?

Acute Amiodarone Pulmonary Toxicity

Amiodarone is an effective antiarrhythmic that frequently is used during the perioperative period. Amiodarone possesses a significant adverse reaction profile. Amiodarone-induced pulmonary toxicity (AIPT) is among the most serious adverse effects and is a leading cause of death associated with its use. Despite significant advances in the understanding of AIPT, its etiology and pathogenesis remain incompletely understood. The diagnosis of AIPT is one of exclusion. The clinical manifestations of AIPT are categorized broadly as acute, subacute, and chronic. Acute AIPT is a rarer and more aggressive form of the disease, most often encountered in cardiothoracic surgery. Acute respiratory distress syndrome (ARDS) is the predominating pattern of amiodarone's acute pulmonary toxicity. The incidence, risk factors, pathogenesis, and diagnosis of acute AIPT are speculative. Early cardiothoracic literature investigating AIPT often attributed amiodarone to the development of postoperative ARDS. Subsequent studies have found no association between amiodarone and acute AIPT and ARDS development. As a drug that is frequently prescribed to a patient population deemed most at risk for this fatal disease, the conflicting evidence on acute AIPT needs further investigation and clarification.

Prophylactic amiodarone vs dronedarone for prevention of perioperative arrhythmias in offpump coronary artery bypass grafting: A pilot randomized controlled trial

The aim of this study was to compare the effects of prophylactic dronedarone and amiodarone in prevention of arrhythmias during and following off-pump coronary artery bypass grafting (OPCAB). This randomized, controlled, double-blinded, parallel-group study was carried out on 36 adult male patients aged 30-70 years, with modified Parsonnet score 0-10 undergoing offpump coronary artery bypass grafting. After obtaining approval from the institutional ethics committee and informed consent, the patients were randomly allocated to two equal groups (n=18). In one group, patients were given inj. amiodarone 3mg/kg in 100ml of normal saline prior to skin incision intravenously over 20 minutes. In the second group patients received tablet dronedarone 400mg orally twice daily, commencing three days prior to the date of surgery. Patients in the amiodarone group received placebo tablet while patients in the dronedarone group received placebo infusion for the sake of blinding. The frequency and profile of arrhythmias intraoperatively and 24 hours postoperatively were studied. Intraoperative arrhythmias occurred in 50% of patients receiving amiodarone and 16.67% of patients receiving dronedarone. Maximum ventricular rate during atrial fibrillation was significantly lower in the dronedarone group (121 beats per min) than in the amiodarone group (168 beats per min). The study concludes that dronedarone appears to be at least as effective as amiodarone in prophylaxis of intraoperative and postoperative arrhythmias in patients undergoing OPCAB, with a better control of ventricular response.

Prevention of atrial fibrillation after coronary artery bypass grafting via atrial electromechanical interval and use of amiodarone prophylaxis

In our previous study, we defined a cut-off point of 120 ms for atrial electromechanical interval (AEMi) to determine the risk of atrial fibrillation (AF) occurrence. Accordingly, the present study sought to investigate whether or not a prophylactic perioperative administration of amiodarone could reduce the incidence of AF in a high-risk group (AEMi >120 ms) undergoing coronary artery bypass grafting (CABG). In this prospective, randomized study, 100 patients with AEMi >120 ms received either amiodarone (n=50) or placebo (n=50). The endpoints were AF occurrence after CABG and hospital and intensive care unit (ICU) lengths of stay after CABG. The incidence of postoperative AF was significantly higher in the placebo group than that of the amiodarone group (88% of patients in control group vs. 16% of patients in amiodarone group, P<0.0001). The prophylactic therapy with amiodarone significantly reduced the ICU length of stay (2.28+/-1.00 vs. 3.60+/-0.90 days, P<0.0001) and hospital length of stay (5.64+/-2.35 vs. 7.78+/-1.46 days, P<0.0001). The incidence of postoperative AF among patients with high AEMi was significantly reduced by a prophylactic amiodarone treatment, resulting in shorter ICU and hospital stays.

Prophylactic Amiodarone for Prevention of Atrial Fibrillation After Cardiac Surgery: A Meta-Analysis

Amiodarone has been proposed to decrease atrial fibrillation after cardiac surgery. The literature was systematically reviewed for randomized trials comparing amiodarone with control for prevention of atrial fibrillation. Data were extracted on study characteristics, quality, and incidence of atrial fibrillation, cardiovascular outcomes, and length of hospitalization. Nineteen trials were included. Amiodarone reduced the odds ratio of atrial fibrillation (0.50; 95% confidence interval [CI]: 0.43 to 0.59, p < 0.0001), ventricular tachyarrhythmias (0.39; 95% CI: 0.26 to 0.58, p < 0.0001), and strokes (0.53; 95% CI: 0.30 to 0.92, p = 0.02). Amiodarone reduced hospital stay (0.6 days; 95% CI: 0.4 to 0.8, p < 0.0001). Amiodarone decreased atrial fibrillation, reduced perioperative ventricular tachyarrhythmias and strokes, and reduced duration of hospitalization. The current evidence supports recommending the routine use of perioperative amiodarone for cardiac surgery.

Pharmacologic prophylaxis for postoperative atrial tachyarrhythmia in general thoracic surgery: Evidence from randomized clinical trials

BACKGROUND

Atrial tachyarrhythmia is the most common complication after general thoracic surgery and is associated with significant morbidity, longer hospital stay, and higher costs. We sought to determine whether the use of antiarrhythmic medications is associated with a reduced rate of postoperative atrial tachyarrhythmia.

METHODS

MEDLINE, EMBASE, Cochrane Database of clinical trials (1980-2003), and reference lists of relevant articles were searched for randomized controlled trials with placebo control, general thoracic patients, and noncombined and prophylactic use of the medications. Search, data abstraction, and analyses were performed and confirmed by at least 2 authors. A fixed-effects model was used to perform meta-analyses.

RESULTS

There were 11 unique trials (total n = 1294) that met the inclusion criteria. Calcium-channel blockers and beta-blockers reduced the risk of atrial tachyarrhythmia in 4 and 2 trials, respectively (relative risk of 0.50 and 95% confidence interval of 0.34-0.73; relative risk of 0.40 and 95% confidence interval of 0.17-0.95, respectively). However, beta-blockers tended to increase the risk of pulmonary edema (relative risk, 2.15; 95% confidence interval, 0.74-6.23). Magnesium tested in one unblinded trial also reduced the risk of atrial tachyarrhythmia (relative risk, 0.4; 95% confidence interval, 0.21-0.78). On the other hand, digitalis preparations were found to be harmful because they increased the risk of atrial tachyarrhythmia in 3 trials (relative risk, 1.51; 95% confidence interval, 1.00-2.28). Finally, 2 other medications, flecainide and amiodarone, were each tested in a single small trial, and their effects were associated with great uncertainty.

CONCLUSIONS

Calcium-channel blockers and beta-blockers are effective in reducing postoperative atrial tachyarrhythmia. The use of these medications should be individualized, and possible adverse events of beta-blockers should be taken into account. Randomized clinical trials do not support the use of digitalis in general thoracic surgery. The value of magnesium as a supplement to a main prophylactic regimen should be explored.

Giving IV and Oral Amiodarone Perioperatively for the Prevention of Postoperative Atrial Fibrillation in Patients Undergoing Coronary Artery Bypass Surgery

PURPOSES

We studied the use of perioperative IV and oral administration of amiodarone for the prevention of postoperative atrial fibrillation in patients undergoing coronary artery bypass graft surgery (CABG).

BACKGROUND

In the United States, > 500,000 patients undergo CABG each year. Numerous studies to date have suggested that postoperative atrial fibrillation occurs in 30 to 50% of patients, leading to significant morbidity, including hypotension, heart failure, thromboembolic complications, prolonged hospital stay, and increased hospital costs. The objective of this study was to assess the use of IV amiodarone in combination with oral amiodarone to reduce the incidence of postoperative atrial fibrillation.

METHOD

From January 1999 to October 1999, 51 patients scheduled for CABG were randomly selected for participation in the amiodarone administration trial. IV amiodarone, 0.73 mg/min, was administered on call to the operating room for 48 h, followed by oral amiodarone, 400 mg q12h, for the next 3 days. The amiodarone group was case-control matched to the incidence of postoperative atrial fibrillation in 92 patients undergoing CABG using conventional medical therapy during the same period. The primary end point of this study was the incidence of postoperative atrial fibrillation, length of hospital stay, and hospital costs, compared to the control group undergoing CABG during the same time.

RESULTS

Atrial fibrillation occurred in 3 of 51 patients (5.88%) in the amiodarone group, compared to 24 of 92 patients (26.08%) in the control group. Length of hospital stay in the amiodarone group was less than in the control group (5.3 days vs 6.7 days), with a trend toward decrease in hospital costs.

CONCLUSION

The administration of IV amiodarone in conjunction with oral amiodarone for a total dose of 4,500 mg over 5 days appears to be a hemodynamically well-tolerated, safe, and effective treatment in decreasing the incidence of postoperative atrial fibrillation, shortening length of stay, and a trend toward lowering hospital costs, even in patients with significantly reduced left ventricular function (< 30%). A large multicenter study using IV and oral amiodarone should be pursued prior to deciding whether its use should become standard therapy in all patients undergoing CABG in order to decrease the incidence of postoperative atrial fibrillation.

Ventricular reconstruction for ischemic cardiomyopathy

Left ventricular surgical reconstruction has been advocated for patients with coronary artery disease, prior myocardial infarction, and poor left ventricular function. The objective of the approach is to resect or exclude all akinetic or dyskinetic nonfunctioning portions of the ventricular cavity and to restore the left ventricle size and shape toward normal as much as possible. We review the pathophysiology of ischemic cardiomyopathy and suggest guidelines for preoperative assessment and patient selection for ventricular reconstruction. Because of the prevalence and prognostic significance of ventricular arrhythmias in this patient population we include in our operative approach a visually directed ablation procedure in those with significant septal scarring. We describe our operative technique and review results achieved with this approach. The procedure results in a significant decrease in ventricular volume, increase in ejection fraction and improvement in apical geometry. We conclude that in selected patients with ischemic cardiomyopathy, left ventricular reconstruction can be accomplished with low operative mortality and results in significant improvement in left ventricular function. During follow up symptom class is decreased in most patients and overall survival at 5 years is 84% and freedom from sudden death is 96%. Ventricular reconstruction should be considered in all patients with coronary artery disease and akinetic or dyskinetic scar.

Long-term amiodarone therapy and the risk of complications after cardiac surgery: results from the Canadian Amiodarone Myocardial Infarction Arrhythmia Trial (CAMIAT)

OBJECTIVE

This study was undertaken to determine the association between amiodarone therapy and risk of complications of cardiac surgery in patients in the randomized placebo-controlled, double-blind Canadian Amiodarone Myocardial Infarction Arrhythmia Trial.

METHODS

Prospectively collected data regarding postoperative complications in 82 patients who underwent cardiac surgery during Canadian Amiodarone Myocardial Infarction Arrhythmia Trial participation were analyzed; 36 patients were randomly assigned to receive amiodarone and 46 were assigned to receive placebo. Of the patients randomly assigned to receive amiodarone, 24 patients continued amiodarone treatment to within 7 days of the operation (active amiodarone group) and 12 patients had the amiodarone discontinued at least 7 days before the operation (discontinued amiodarone group).

RESULTS

The baseline characteristics of the three groups were similar. The risks of ventricular fibrillation, atrial fibrillation, and respiratory complications were similar. The risk of requiring an intra-aortic balloon pump was significantly increased by amiodarone (34.8% vs 16.7% vs 8.7% for active amiodarone, discontinued amiodarone, and placebo groups, respectively, P =.024). There was no significant difference in the use of temporary pacing. Neither the mean duration of stay in the intensive care unit nor the 7- and 30-days mortalities were affected by amiodarone.

CONCLUSIONS

Patients receiving long-term amiodarone treatment after myocardial infarction had a higher rate of intra-aortic balloon use after cardiac surgery. There was no increased risk of pulmonary complications, need for pacing, or death.

Left ventricular reconstruction for ischemic cardiomyopathy

An outline of the Toronto General Hospital's philosophy for revascularization and left ventricular reconstruction in patients with ischemic cardiomyopathy. An open beating heart technique with modified linear closure and septoplasty when indicated is used for repair of both akinetic and dyskinetic scar. Patient selection, OR mortality (2.6%), and long-term results are reviewed.

Acute pulmonary toxicity after low-dose amiodarone therapy

Amiodarone-induced pulmonary toxicity is usually seen in cardiac surgical patients who have received large doses of amiodarone for ventricular arrhythmias over prolonged periods. In this report, we describe a case of amiodarone-induced pulmonary toxicity after a short course of therapy for postoperative atrial fibrillation.

Postoperative arrhythmias and conduction disorders

Cardiac arrhythmias are common in the perioperative period. Most arrhythmias are clinically benign. Occasionally, cardiac arrhythmias and conduction disturbances can pose a major additional risk to the patient in the perioperative and postoperative periods. The current availability of a wide array of techniques for controlling serious arrhythmias--pharmacologic, electrical, and interventional--enable the physician to manage most arrhythmias and conduction disturbances successfully. The added risks posed by arrhythmias and conduction disturbances in the perioperative period now can be minimized.

Repair of dyskinetic or akinetic left ventricular aneurysm: results obtained with a modified linear closure

OBJECTIVE

In patients with a dyskinetic or akinetic area of the left ventricle, controversy exists over who will benefit from resection. This study evaluates results achieved with a modified linear closure in 193 of 196 consecutive cases. Preoperative cases (n = 160 [83%]) were in functional class III or IV with congestive heart failure (n = 115 [60%]), angina (n = 108 [56%]), and syncope (n = 67 [35%]). The ejection fraction was 25% +/- 8%, and echocardiography showed significant mitral regurgitation in 86 (45%) patients. In patients with detailed wall motion analysis, 50 (57%) were akinetic, and 37 (43%) were dyskinetic.

METHODS

Repair was completed on the beating heart to minimize ischemia and allow assessment of wall function and viability to guide resection and repair. Additional procedures included coronary artery bypass grafting (n = 175 [91%]), septoplasty (n = 24 [12%]), and arrhythmia ablation (n = 77 [40%]). Ventricular and mitral valve function were assessed by means of preoperative and/or postoperative gated acquisition scans in 171 (90%) patients and Doppler echocardiograms in 170 (88%) patients.

RESULTS

Hospital mortality was low (5/193 [2.6%]), although 34 (18%) patients needed perioperative intra-aortic balloon pump support. Actuarial survival at 1 and 5 years was 91% and 84%. Most late deaths were due to congestive heart failure. Seven patients required transplantation (interval, 36 +/- 32 months). As determined by multivariable analysis, factors predicting poor outcome at 5 years were preoperative mitral regurgitation of 2+ or greater, congestive heart failure, and ventricular tachycardia. Among survivors, 126 (80%) of 157 were in functional class I or II, and the average increase in ejection fraction postoperatively was 9.1% +/- 10.0%. Postoperative echocardiograms in 70 patients with significant mitral regurgitation preoperatively showed improved valve function in 40 (57%) of 70 patients.

CONCLUSIONS

We conclude that repair of dyskinetic or akinetic aneurysms by means of a modified linear closure plus septoplasty in selected patients can be accomplished in the beating heart with low operative mortality, provides good symptomatic relief and long-term survival, and is associated with objective evidence of improved left ventricular and mitral valve function.

The Management of Atrial Fibrillation in the ICU

Atrial tachyarrhythmias are the most frequent arrhythmias occurring in ICU patients, being particularly common in patients with cardiovascular and respiratory failure. Unlike ambulatory patients in whom atrial fibrillation/flutter (AF) is likely to be short lived, in the critically ill these arrhythmias are unlikely to resolve until the underlying disease process has improved. Urgent cardioversion is indicated for hemodynamic instability. Treatment in hemodynamically stable patients includes correction of treatable precipitating factors, control of the ventricular response rate, conversion to sinus rhythm, and prophylaxis against thromboembolic events in those patients who remain in AF. Diltiazem is the preferred agent for rate control, while procainamide and amiodarone are generally considered to be the antiarrhythmic agents of choice.

Oral d,l sotalol reduces the incidence of postoperative atrial fibrillation in coronary artery bypass surgery patients: a randomized, double-blind, placebo-controlled study

OBJECTIVES

The purpose of this prospective, randomized, double-blind, placebo-controlled study was to assess the efficacy of preoperatively and postoperatively administered oral d,l sotalol in preventing the occurrence of postoperative atrial fibrillation (AF).

BACKGROUND

Atrial fibrillation is the most common arrhythmia following coronary artery bypass surgery (CABG). Its etiology, prevention and treatment remain highly controversial. Furthermore, its associated morbidity results in a prolongation of the length of hospital stay post-CABG.

METHODS

A total of 85 patients, of which 73 were to undergo CABG and 12 CABG plus valvular surgery (ejection fraction > or = 28% and absence of clinical heart failure), were randomized to receive either sotalol (40 patients; mean dose = 190 +/- 43 mg/day) started 24 to 48 h before open heart surgery and continued for four days postoperatively, or placebo (45 patients, mean dose = 176 +/- 32 mg/day).

RESULTS

Atrial fibrillation occurred in a total of 22/85 (26%) patients. The incidence of postoperative AF was significantly (p = 0.008) lower in patients on sotalol (12.5%) as compared with placebo (38%). Significant bradycardia/hypotension, necessitating drug withdrawal, occurred in 2 of 40 (5%) patients on sotalol and none in the placebo group (p = 0.2). None of the patients on sotalol developed Torsade de pointes or sustained ventricular arrhythmias. Postoperative mortality was not significantly different in sotalol versus placebo (0% vs. 2%, p = 1.0). Patients in the sotalol group had a nonsignificantly shorter length of hospital stay as compared with placebo (7 +/- 2 days vs. 8 +/- 4 days; p = 0.24).

CONCLUSIONS

The administration of sotalol, in dosages ranging from 80 to 120 mg, was associated with a significant decrease (67%) in postoperative AF in patients undergoing CABG without appreciable side effects. Sotalol should be considered for the prevention of postoperative AF in patients undergoing CABG in the absence of heart failure and significant left ventricular dysfunction.

Pro: All patients should receive pharmacologic prophylaxis for atrial fibrillation after cardiac surgery

In addition to the physiologic manifestations of atrial fibrillation (stroke, ventricular arrhythmia), patients with postoperative arrhythmias have subjective concerns because of symptoms (palpitations), and prolonged length of stay and hospital cost are significant sources of visceral morbidity to both patients and their physicians. Efforts to terminate this arrhythmia after its initiation are fraught with problems ranging from ineffectiveness to toxicity. Fortunately, a variety of pharmacologic strategies are now available to prevent atrial fibrillation after cardiac surgery. At a minimum, low-dose postoperative beta-adrenergic blockade is valuable for patients who receive these medications preoperatively and may be beneficial in all patients. Moreover, emerging data suggest that prophylaxis with antiarrhythmic compounds can significantly decrease the incidence of atrial fibrillation, length of hospital stay, and cost. Future trials will be focused on evaluating the risks and benefits of the newer prophylactic therapies and defining which subpopulations benefit most from such therapy.

Anaesthesia for transmyocardial laser revascularization--initial experience with seven patients

The introduction of transmyocardial laser revascularization for ischaemic heart disease has brought with it new challenges for anaesthetists. These include acute deterioration of cardiac function, the need for emergency cardiopulmonary bypass and difficulty weaning from haemodynamic support. Recurrent arrhythmias can occur despite amiodarone prophylaxis. We describe our initial experience and the problems we encountered.

Preoperative therapy with amiodarone and the incidence of acute organ dysfunction after cardiac surgery

We examined the influence of preoperative therapy with amiodarone on the incidence of acute organ dysfunction after cardiac surgery in a matched case-control study. There were 220 case-control pairs matched by day of surgery, source of admission, demographic characteristics, placement of intraaortic balloon pump before surgery, repeat operations, emergency surgery, thoracic aorta surgery and other surgical procedures. History of congestive heart failure was more prevalent in the amiodarone group than in the control group before surgery (60% vs 38%, P < 0.0001). The incidence of acute organ dysfunction, duration of mechanical ventilation, and death was similar in both groups after surgery. The requirement for inotropes (26% vs 17%, P = 0.03) and vasopressors (66% vs 55%, P = 0.02) and the incidence of postoperative nosocomial infections (12% vs 6%, P = 0.04) was greater in the amiodarone group. However, the difference was not significant after adjustment for congestive heart failure (Cochran-Mantel-Haenszel test P = 0.15, P = 0.25, P = 0.16, respectively). Amiodarone did not increase the incidence of acute organ dysfunction or death after cardiac surgery. The requirement for inotropes and vasopressors and the incidence of nosocomial infections were related to the severity of the underlying cardiac disease. The practice of discontinuing amiodarone treatment before surgery to reduce the incidence of postoperative organ dysfunction should be critically reevaluated.

IMPLICATIONS

Amiodarone is often used for the treatment of life-threatening rhythm disorder. Amiodarone has been blamed for causing organ injury after cardiac surgery. In a study of 220 patients, amiodarone did not increase the risk of organ injury or death after cardiac surgery when compared with control patients. There was no evidence to support the practice of stopping amiodarone before cardiac surgery to avoid serious complications.

Low-dose amiodarone-related complications after cardiac operations

OBJECTIVE

High-dose preoperative amiodarone therapy has been implicated as a risk factor for serious complications after cardiac operations. To investigate the effect of preoperative low-dose amiodarone treatment on early postoperative outcome after cardiac operations, we prospectively studied 88 patients.

METHODS

Forty-four patients were receiving amiodarone (mean daily dose +/- standard deviation, 205 +/- 70 mg/day) and 44 patients were controls matched in pairs. The following parameters were recorded after the operation in all patients: (1) the ratio of oxygen tension to inspired oxygen fraction on arrival in the intensive care unit and 2, 4, 6, 10, 14, 18, and 22 hours thereafter; (2) the occurrence of acute respiratory distress syndrome; (3) early postoperative cardiac complications; and (4) the type and number of inotropic agents or vasopressors (or both) needed.

RESULTS

No difference in the ratio of oxygen tension to inspired oxygen fraction was noted at the various time intervals between amiodarone-treated patients and control patients. Overall, only one patient had acute respiratory distress syndrome in the amiodarone group, but he had multiple other factors known to predispose to acute lung injury. Several cardiac complications, such as pulmonary edema, temporary pacing, and need for intraaortic balloon pump counterpulsation, were observed more frequently in amiodarone-treated patients than in control patients. In addition, amiodarone-treated patients required more frequent inotropic support (73% vs 43%, p = 0.003) and more inotropic drugs or vasopressors (or both) per patient than did control patients (1.4 +/- 1.1 vs 0.6 +/- 0.8, p = 0.002).

CONCLUSION

Preoperative low-dose amiodarone therapy does not seem to be related to significant postoperative lung toxicity, but it is associated with various cardiac complications and an increased need for more intense inotropic support after cardiac operations. These findings may be related to the drug's depressant effect on the myocardium.