- Email: [email protected]
Selective Use of Amiodarone and Early Cardioversion for Postoperative Atrial Fibrillation
Louis E. Samuels, MD, Elena C. Holmes, CRNP, and Fania L. Samuels, MD Department of Cardiothoracic Surgery, The Lankenau Hospital, Wynnewood, Pennsylvania, Division of Electrophysiology, Hahnemann University Hospital, Philadelphia, Pennsylvania
Background. Postoperative atrial fibrillation (AF) occurs in 20%– 40% of patients undergoing open-heart surgery. Numerous pharmacological and electrical therapies have been used as a prophylaxis to prevent this dysrhythmia. The purpose of this study was to examine the selective use of amiodarone and early cardioversion (CVN) postoperatively to restore normal sinus rhythm (NSR). Methods. A retrospective nonrandomized review of patients who received amiodarone and early electrical CVN (study group) for postoperative AF after coronary artery bypass grafting (CABG) were compared with patients who received nonamiodarone therapies (control group). The study group received 150 mg of amiodarone bolus intravenously and thereafter received an infusion of 1 g over a 24-hour period. If NSR was established within 24 hours, then the intravenous (IV) infusion was continued for another 24 hours with concomitant oral amiodarone overlap. If NSR was not established within 24 hours, then external electrical CVN was performed. After 48 hours, the IV infusion was discontinued and the oral regimen maintained through discharge. Control group patients received either combination digoxin and procainamide or diltiazem. Postoperative -blocker administration was instituted in all patients.
Results. Six-hundred forty consecutive CABG patients were examined between July 1995 and June 2003. Postoperative AF developed in 160 of these patients (25%). One-hundred patients constituted the study group and 60 patients represented the control group. Restoration of NSR within 24 and 48 hours occurred in 79 (79%) and 90 patients (90%) for the study group, respectively, compared with 38 (64%) and 44 patients (73%) for the control group, respectively. The presence of NSR at discharge was achieved in 98 study patients (98%) and 50 control patients (83%). The length of stay (LOS) for the study and control patients was 7.4 and 9.1 days, respectively. There was no mortality in either group. Conclusions. Amiodarone and early CVN was more effective than nonamiodarone therapies with regard to restoring NSR for patients in whom AF developed after elective CABG. A trend toward a decrease in LOS was observed in the study group, but was not statistically significant. The overall LOS using amiodarone therapy with early CVN was similar to postoperative AF for patients in whom the condition did not develop.
T
Material and Methods
he occurrence of atrial fibrillation (AF) is inevitable with regard to the practice of open-heart surgery. Although chemical and electrical strategies have attempted to eradicate this phenomenon, no method has proven to be completely successful. Decades of trials have attempted to prevent the occurrence of postoperative AF with varying degrees of success. The purpose of this study was to examine the role of amiodarone and early electrical cardioversion (CVN) with regard to restoring normal sinus rhythm (NSR) in patients who have undergone coronary artery bypass grafting (CABG) with postoperative AF. This study group was compared with patients who did not receive amiodarone and early electrical CVN after the development of postoperative AF. Accepted for publication June 11, 2004. Address reprints requests to Dr Samuels, The Lankenau Hospital, Medical Science Bldg, Suite #280, 100 Lancaster Ave, Wynnewood, PA 19096; e-mail: [email protected].
© 2005 by The Society of Thoracic Surgeons Published by Elsevier Inc
(Ann Thorac Surg 2005;79:113– 6) © 2005 by The Society of Thoracic Surgeons
A retrospective nonrandomized review of patients undergoing CABG, in which a single surgeon at the same institution performed all of the procedures, were examined between July 1995 and June 2003. All surgeries were executed with the aid of cardiopulmonary bypass (CPB), antegrade cold blood cardioplegia, and mild hypothermia. A review of the therapies used to treat postoperative AF was assessed. Two therapeutic groups were identified. The study group consisted of patients who received amiodarone and early electrical CVN. Patient informed consent was obtained for the use of off-label amiodarone to treat postoperative AF. Procedural consent was obtained to use electrical CVN with regard to the restoration of NSR. The control group consisted of patients who received nonamiodarone therapies. Between July 1995 and June 2000, postoperative AF was treated with combination digoxin and procainamide or diltiazem—these patients constituted the control group. Between July 2000 and June 2003, postoperative AF was treated with amio0003-4975/05/$30.00 doi:10.1016/j.athoracsur.2004.06.049
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SAMUELS ET AL AMIODARONE FOR POSTOPERATIVE AF
Ann Thorac Surg 2005;79:113– 6
Table 2. Results Outcome
Non-Amiodorane (n ⫽ 60)
Amiodorane (n ⫽ 100)
p Value
NSR @ 24 hrs NSR @ 48 hrs NSR @ DC TEE CVN Anticoagulation LOS (days)a (SD)
38 44 50 5 5 5 9.1 (1.704)
79 90 98 0 10 0 7.9 (1.703)
0.0423 0.0078 0.0011 0.0067 NS 0.0067 0.147
a
Standard deviation (SD) using Student’s t test.
CVN ⫽ cardioversion; DC ⫽ direct current; LOS ⫽ length of stay; TEE ⫽ transesophageal echocardiographylitus; HTN ⫽ hypertension; NS ⫽ not significant; SD ⫽ standard deviation.
Fig 1. Amiodarone and early electrical cardioversion (CVN) protocol. * ⫽ metoprolol used in all cases (25 mg by mouth [PO] twice a day [BID]). (A-Fib ⫽ atrial fibrillation; IV ⫽ intravenous; NSR ⫽ normal sinus rhythm; Post Op A-Fib ⫽ postoperative atrial fibrillation; TID ⫽ three times a day.)
darone and early (ⱕ 24 hours) CVN—these patients constituted the study group. Patients with preexisting arrhythmia (or when observed during preoperative antiarrhythmic therapy) were excluded from the study, including those patients exhibiting a history of paroxysmal AF. Emergent patients exhibiting recent myocardial infarction were also excluded from the study. Rhythm identification was obtained by 24-hour telemetry monitoring and confirmed with 12-lead electrocardiography. The study group received 150 mg of amiodarone bolus intravenously and thereafter received an infusion of 1 g over a 24-hour period. If NSR was established within 24 hours, then the intravenous (IV) infusion was continued for another 24 hours with concomitant oral amiodarone (200 mg three times a day [TID]) overlap. If NSR was not established within 24 hours, then external electrical CVN was performed. After 48 hours the IV infusion was Table 1. Demographics Non-Amiodorane Amiodorane p (n ⫽ 60) (n ⫽ 100) Value Age (yrs) Gender (male:female ratio) HTN DM COPD CRI BB ACE-I CCB Diuretic
66 38:22
67 59:41
NS NS
38 25 9 5 43 15 9 17
68 44 13 10 73 30 12 26
NS NS NS NS NS NS NS NS
ACE-I ⫽ angiotensin converting enzyme inhibitor; BB ⫽ -blocker; CCB ⫽ calcium channel blocker; COPD ⫽ chronic obstructive pulmonary disease; CRI ⫽ ; chronic renal insufficiency; DM ⫽ diabetes mellitus; HTN ⫽ hypertension; NS ⫽ not significant.
discontinued and the oral regimen maintained until discharge (Fig 1). The therapy for the control group included a combination of digoxin and procainamide or IV and oral diltiazem. A digoxin dosage of 1 g was given intravenously over a 24-hour period and thereafter a daily oral dosage of 0.25 mg was given. A procainamide dosage of 1 g was given intravenously as a bolus and thereafter an IV infusion of 1 mg/min over a 24-hour period— oral procainamide (500 mg twice a day [BID]) was instituted the next day with subsequent discontinuation of IV infusion. Alternatively IV diltiazem was given as a bolus and thereafter by an infusion titrated for heart rate. The IV diltiazem was discontinued between 24 – 48 hours after the second oral diltiazem dose (30 mg TID) was administered. Electrical CVN was performed for the control group on a selective basis. For those patients who were not cardioverted, rate control and anticoagulation was instituted if NSR was not established by the 48-hour mark. -blocker administration (metoprolol 25 mg BID) was instituted in all patients. Patients who were not given postoperative -blocker therapy were excluded from the analysis. The conduct of the operation and the postoperative protocols were kept constant for all of the patients during the two time periods (1995–2000 and 2000 –2003). Follow-up was limited to 4 weeks from the time of discharge. Statistical analysis between the two groups was performed using Fisher’s exact test and Student’s t test when applicable.
Results There were 640 consecutive elective CABG procedures performed between July 1995 and June 2003. Overall, postoperative AF developed in 160 patients (25%). The demographic profile of the two groups was similar with respect to age, gender, and comorbid conditions (Table 1). Similarly the two groups were comparable with respect to preoperative medications (ie, -blockers, calcium-channelblockers, angiotensin-converting enzyme inhibitors, and diuretics). In the control group, 45 patients (75%) were treated using a combination digoxin and procainamide, whereas 15 patients (15%) were treated using diltiazem.
SAMUELS ET AL AMIODARONE FOR POSTOPERATIVE AF
Table 3. Adverse Events Non-Amiodorane Amiodorane p (n ⫽ 60) (n ⫽ 100) Value Mortality Stroke Perioperative MI Prolonged ventilation VT/VF ARF/HD Surgical infection
0 1 1 3 1 1 1
0 1 2 4 2 1 2
NS NS NS NS NS NS NS
ARF/HD ⫽ acute renal failure/hemodialysis; MI ⫽ myocardial infarction; VT/VF ⫽ ventricular tachycardia/ventricular fibrillation.
There was no significant difference regarding the patient profiles between the two categories within the control group. Restoration of NSR within 24 – 48 hours occurred in 79 (79%) and 90 patients (90%) from the study group, respectively, compared with 38 (63%) and 44 patients (73%) from the control group, respectively. The presence of NSR at discharge was achieved in 98 study patients (98%) and 50 control patients (83%). There was no significant difference with regard to the outcome between the two categories (ie, digoxin/procainamide and diltiazem) in the control group. Patients who remained in AF at the time of discharge were placed on anticoagulation. The need for electrical CVN in an effort to restore NSR was necessary in 10 patients from the study group. The length of stay (LOS) for study and control patients was 7.4 and 9.1 days, respectively (Table 2). There was no mortality in either group. The incidence of adverse events was similar in both groups (Table 3). There was no need for transesophageal echocardiography (TEE) in the study group. Five patients in the control group underwent TEE before electrical CVN. Lastly, 2 patients (2%) in the study group required anticoagulation for persistent AF, whereas 10 patients (17%) required anticoagulation in the control group. At 1 month after release, 2 out of 58 study patients (3.4%) discharged with NSR required readmission for recurrent AF and 8 out of 90 control patients (8.9%) discharged with NSR required readmission for recurrent AF. At 1 month after discharge, all of the study patients and 7 of the 10 control patients who were discharged with AF on anticoagulation were experiencing NSR at this time frame.
Comment The incidence rate of postoperative AF in cardiac surgery ranges between 20%–50% [1]. Despite initial enthusiasm regarding a reduction in postoperative AF regarding off-pump CABG [2], subsequent reports cite similar rates for CABG performed with CPB [3]. This study occurred during a period in which all CABG procedures were performed with CPB (ie, on-pump) with standard protocols for perioperative management by a single surgeon. Therefore variables with regard to technique, style, and therapy were kept minimal. In a similar fashion a single
115
type of -blocker (ie, metoprolol) at a fixed dose (ie, 25 mg by mouth [PO] BID) was used to standardize the therapy to avoid outcome differences associated with the numerous types and dosing of the various commercially available -blockers. Efforts to prevent the development of postoperative AF using a multitude of prophylaxis protocols has resulted in varying degrees of success. The use of prophylactic amiodarone, for example, has been well-documented, with postoperative AF occurring in as low as 5% [4, 5] to as high as 35% [6] of the study patients. Several other studies administered amiodarone as the agent of choice with regard to prophylaxis [7–10] and have reported differing outcomes depending upon the patient population, the route of drug administration, the duration of drug administration, and the presence or absence of -blocker therapy. In this study amiodarone was used selectively with the overall goal of establishing NSR within 24 hours. Irrespective of preoperative medications, all patients received -blocker therapy thus minimizing the effects of “-blocker withdrawal” on outcome. In an effort to approach the problem from another perspective, our goal was to compare a traditional strategy of treatment (ie, digoxin and procainamide or diltiazem) with a new protocol using a combination of IV and oral amiodarone selectively. The rational for the protocol was based on the observation of two separate studies using IV amiodarone [6] and oral amiodarone [11] prophylactically. Although both studies indicated efficacy compared with the control groups, the incidence of AF was still significant—25% and 35%. In contrast to these studies and others investigations, we added the component of early electrical CVN at the 48-hour mark to avoid the necessity for anticoagulation. Although there is no established necessity for anticoagulation after 48 hours regarding heart surgery patients in whom AF developed, the common practice is to, nonetheless, institute heparin and coumadin therapy to avoid stroke. Thus the goal of our investigation was to determine if NSR could be accomplished within 48 hours of the onset of postoperative AF to restore the postoperative course of the patient as though the arrhythmia never occurred. Compared with the original management using digoxin and procainamide or diltiazem, the study patients demonstrated superior conversion rates at all time intervals. Furthermore the use of early electrical CVN obviated the necessity for anticoagulation and TEE. Although it was our observation that this study protocol was responsible for a decrease in the average LOS by nearly 36 hours, the small study size did not indicate statistical significance. The average LOS for contemporaneous CABG patients without the development of postoperative AF was comparable with the study group at 7.5 days. The average LOS for non-AF patients did not change significantly during the entire study period. Although a financial analysis was not performed with regard to this research, the reduced LOS as well as the avoidance of TEE and anticoagulation suggests that a cost decrease would exist.
CARDIOVASCULAR
Ann Thorac Surg 2005;79:113– 6
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SAMUELS ET AL AMIODARONE FOR POSTOPERATIVE AF
There are several limitations inherent to this study, including a relatively small sample size and limited follow-up. Although this was a retrospective, nonrandomized, nonblinded, and historically controlled review the data supports a favorable response with regard to the use of amiodarone as a superior antiarrhythmic therapy to treat postoperative AF and the role of early CVN to restore NSR. This combination of pharmacological and electrical therapies results in a LOS equivalent to those patients who never experienced postoperative AF. In conclusion the use of amiodarone and early electrical CVN is a safe, practical, and efficacious approach to the CABG patient in whom postoperative AF often develops. Selective pharmacologic treatment in combination with selective electrical therapy, as opposed to prophylactic treatment, may obviate the unnecessary and, thus far, ineffective prophylaxis regimens.
References 1. Burke SW, Solomon AJ. Atrial fibrillation in patients after cardiovascular surgery : incidence, risk factors, preventive and therapeutic strategies. Am J Cardiovasc Drugs 2003;3: 95–100. 2. D’Amato TA, Savage EB, Wiechmann RJ, Sakert T, Benckart DH, Magovern JA. Reduced incidence of atrial fibrillation with minimally invasive direct coronary artery bypass. Ann Thorac Surg 2000;70:2013– 6.
Ann Thorac Surg 2005;79:113– 6
3. Legare JF, Buth KJ, King S, et al. Coronary bypass surgery performed off pump does not result in lower in-hospital morbidity than coronary artery bypass grafting performed on pump. Circulation 2004;109:887–92. 4. Hohnloser SH, Meinertz T, Dammbacher T, et al. Electrocardiographic and antiarrhythmic effects of intravenous amiodarone: results of a prospective, placebo-controlled study. Am Heart J 1991;121:89 –95. 5. Katariya K, DeMarchena E, Bolooki H. Oral amiodarone reduces incidence of postoperative atrial fibrillation. Ann Thorac Surg 1999;68:1599 – 603. 6. Guarnieri T, Nolan S, Gottlieb SO, et al. Intravenous amiodarone for the prevention of atrial fibrillation after open heart surgery: The Amiodarone Reduction in Coronary Heart (ARCH) Trial. J Am Coll Cardiol 1999;34:343–7. 7. Butler J, Harriss DR, Sinclair M, Westaby S. Amiodarone prophylaxis for tachycardias after coronary artery surgery: a randomised, double blind, placebo controlled trial. Br Heart J 1993;70:56 – 60. 8. Redle JD, Khurana S, Marzan R, et al. Prophylactic oral amiodarone compared with placebo for prevention of atrial fibrillation after coronary artery bypass surgery. Am Heart J 1999;138:144 –50. 9. Dorge H, Schoendube FA, Schoberer M, et al. Intraoperative amiodarone as prophylaxis against atrial fibrillation after coronary operations. Ann Thorac Surg 2000;69:1358 – 62. 10. Yagdi T, Nalbantgil S, Ayik F, et al. Amiodarone reduces the incidence of atrial fibrillation after coronary artery bypass grafting. J Thorac Cardiovasc Surg 2003;125:1420 –5. 11. Daoud EG, Strickberger SA, Man KC, et al. Preoperative Amiodarone as Prophylaxis Against Atrial Fibrillation After Heart Surgery. New Engl J Med 1997;337:1785–91.
Background. Postoperative atrial fibrillation (AF) occurs in 20%– 40% of patients undergoing open-heart surgery. Numerous pharmacological and electrical therapies have been used as a prophylaxis to prevent this dysrhythmia. The purpose of this study was to examine the selective use of amiodarone and early cardioversion (CVN) postoperatively to restore normal sinus rhythm (NSR). Methods. A retrospective nonrandomized review of patients who received amiodarone and early electrical CVN (study group) for postoperative AF after coronary artery bypass grafting (CABG) were compared with patients who received nonamiodarone therapies (control group). The study group received 150 mg of amiodarone bolus intravenously and thereafter received an infusion of 1 g over a 24-hour period. If NSR was established within 24 hours, then the intravenous (IV) infusion was continued for another 24 hours with concomitant oral amiodarone overlap. If NSR was not established within 24 hours, then external electrical CVN was performed. After 48 hours, the IV infusion was discontinued and the oral regimen maintained through discharge. Control group patients received either combination digoxin and procainamide or diltiazem. Postoperative -blocker administration was instituted in all patients.
Results. Six-hundred forty consecutive CABG patients were examined between July 1995 and June 2003. Postoperative AF developed in 160 of these patients (25%). One-hundred patients constituted the study group and 60 patients represented the control group. Restoration of NSR within 24 and 48 hours occurred in 79 (79%) and 90 patients (90%) for the study group, respectively, compared with 38 (64%) and 44 patients (73%) for the control group, respectively. The presence of NSR at discharge was achieved in 98 study patients (98%) and 50 control patients (83%). The length of stay (LOS) for the study and control patients was 7.4 and 9.1 days, respectively. There was no mortality in either group. Conclusions. Amiodarone and early CVN was more effective than nonamiodarone therapies with regard to restoring NSR for patients in whom AF developed after elective CABG. A trend toward a decrease in LOS was observed in the study group, but was not statistically significant. The overall LOS using amiodarone therapy with early CVN was similar to postoperative AF for patients in whom the condition did not develop.
T
Material and Methods
he occurrence of atrial fibrillation (AF) is inevitable with regard to the practice of open-heart surgery. Although chemical and electrical strategies have attempted to eradicate this phenomenon, no method has proven to be completely successful. Decades of trials have attempted to prevent the occurrence of postoperative AF with varying degrees of success. The purpose of this study was to examine the role of amiodarone and early electrical cardioversion (CVN) with regard to restoring normal sinus rhythm (NSR) in patients who have undergone coronary artery bypass grafting (CABG) with postoperative AF. This study group was compared with patients who did not receive amiodarone and early electrical CVN after the development of postoperative AF. Accepted for publication June 11, 2004. Address reprints requests to Dr Samuels, The Lankenau Hospital, Medical Science Bldg, Suite #280, 100 Lancaster Ave, Wynnewood, PA 19096; e-mail: [email protected].
© 2005 by The Society of Thoracic Surgeons Published by Elsevier Inc
(Ann Thorac Surg 2005;79:113– 6) © 2005 by The Society of Thoracic Surgeons
A retrospective nonrandomized review of patients undergoing CABG, in which a single surgeon at the same institution performed all of the procedures, were examined between July 1995 and June 2003. All surgeries were executed with the aid of cardiopulmonary bypass (CPB), antegrade cold blood cardioplegia, and mild hypothermia. A review of the therapies used to treat postoperative AF was assessed. Two therapeutic groups were identified. The study group consisted of patients who received amiodarone and early electrical CVN. Patient informed consent was obtained for the use of off-label amiodarone to treat postoperative AF. Procedural consent was obtained to use electrical CVN with regard to the restoration of NSR. The control group consisted of patients who received nonamiodarone therapies. Between July 1995 and June 2000, postoperative AF was treated with combination digoxin and procainamide or diltiazem—these patients constituted the control group. Between July 2000 and June 2003, postoperative AF was treated with amio0003-4975/05/$30.00 doi:10.1016/j.athoracsur.2004.06.049
CARDIOVASCULAR
Selective Use of Amiodarone and Early Cardioversion for Postoperative Atrial Fibrillation
CARDIOVASCULAR
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SAMUELS ET AL AMIODARONE FOR POSTOPERATIVE AF
Ann Thorac Surg 2005;79:113– 6
Table 2. Results Outcome
Non-Amiodorane (n ⫽ 60)
Amiodorane (n ⫽ 100)
p Value
NSR @ 24 hrs NSR @ 48 hrs NSR @ DC TEE CVN Anticoagulation LOS (days)a (SD)
38 44 50 5 5 5 9.1 (1.704)
79 90 98 0 10 0 7.9 (1.703)
0.0423 0.0078 0.0011 0.0067 NS 0.0067 0.147
a
Standard deviation (SD) using Student’s t test.
CVN ⫽ cardioversion; DC ⫽ direct current; LOS ⫽ length of stay; TEE ⫽ transesophageal echocardiographylitus; HTN ⫽ hypertension; NS ⫽ not significant; SD ⫽ standard deviation.
Fig 1. Amiodarone and early electrical cardioversion (CVN) protocol. * ⫽ metoprolol used in all cases (25 mg by mouth [PO] twice a day [BID]). (A-Fib ⫽ atrial fibrillation; IV ⫽ intravenous; NSR ⫽ normal sinus rhythm; Post Op A-Fib ⫽ postoperative atrial fibrillation; TID ⫽ three times a day.)
darone and early (ⱕ 24 hours) CVN—these patients constituted the study group. Patients with preexisting arrhythmia (or when observed during preoperative antiarrhythmic therapy) were excluded from the study, including those patients exhibiting a history of paroxysmal AF. Emergent patients exhibiting recent myocardial infarction were also excluded from the study. Rhythm identification was obtained by 24-hour telemetry monitoring and confirmed with 12-lead electrocardiography. The study group received 150 mg of amiodarone bolus intravenously and thereafter received an infusion of 1 g over a 24-hour period. If NSR was established within 24 hours, then the intravenous (IV) infusion was continued for another 24 hours with concomitant oral amiodarone (200 mg three times a day [TID]) overlap. If NSR was not established within 24 hours, then external electrical CVN was performed. After 48 hours the IV infusion was Table 1. Demographics Non-Amiodorane Amiodorane p (n ⫽ 60) (n ⫽ 100) Value Age (yrs) Gender (male:female ratio) HTN DM COPD CRI BB ACE-I CCB Diuretic
66 38:22
67 59:41
NS NS
38 25 9 5 43 15 9 17
68 44 13 10 73 30 12 26
NS NS NS NS NS NS NS NS
ACE-I ⫽ angiotensin converting enzyme inhibitor; BB ⫽ -blocker; CCB ⫽ calcium channel blocker; COPD ⫽ chronic obstructive pulmonary disease; CRI ⫽ ; chronic renal insufficiency; DM ⫽ diabetes mellitus; HTN ⫽ hypertension; NS ⫽ not significant.
discontinued and the oral regimen maintained until discharge (Fig 1). The therapy for the control group included a combination of digoxin and procainamide or IV and oral diltiazem. A digoxin dosage of 1 g was given intravenously over a 24-hour period and thereafter a daily oral dosage of 0.25 mg was given. A procainamide dosage of 1 g was given intravenously as a bolus and thereafter an IV infusion of 1 mg/min over a 24-hour period— oral procainamide (500 mg twice a day [BID]) was instituted the next day with subsequent discontinuation of IV infusion. Alternatively IV diltiazem was given as a bolus and thereafter by an infusion titrated for heart rate. The IV diltiazem was discontinued between 24 – 48 hours after the second oral diltiazem dose (30 mg TID) was administered. Electrical CVN was performed for the control group on a selective basis. For those patients who were not cardioverted, rate control and anticoagulation was instituted if NSR was not established by the 48-hour mark. -blocker administration (metoprolol 25 mg BID) was instituted in all patients. Patients who were not given postoperative -blocker therapy were excluded from the analysis. The conduct of the operation and the postoperative protocols were kept constant for all of the patients during the two time periods (1995–2000 and 2000 –2003). Follow-up was limited to 4 weeks from the time of discharge. Statistical analysis between the two groups was performed using Fisher’s exact test and Student’s t test when applicable.
Results There were 640 consecutive elective CABG procedures performed between July 1995 and June 2003. Overall, postoperative AF developed in 160 patients (25%). The demographic profile of the two groups was similar with respect to age, gender, and comorbid conditions (Table 1). Similarly the two groups were comparable with respect to preoperative medications (ie, -blockers, calcium-channelblockers, angiotensin-converting enzyme inhibitors, and diuretics). In the control group, 45 patients (75%) were treated using a combination digoxin and procainamide, whereas 15 patients (15%) were treated using diltiazem.
SAMUELS ET AL AMIODARONE FOR POSTOPERATIVE AF
Table 3. Adverse Events Non-Amiodorane Amiodorane p (n ⫽ 60) (n ⫽ 100) Value Mortality Stroke Perioperative MI Prolonged ventilation VT/VF ARF/HD Surgical infection
0 1 1 3 1 1 1
0 1 2 4 2 1 2
NS NS NS NS NS NS NS
ARF/HD ⫽ acute renal failure/hemodialysis; MI ⫽ myocardial infarction; VT/VF ⫽ ventricular tachycardia/ventricular fibrillation.
There was no significant difference regarding the patient profiles between the two categories within the control group. Restoration of NSR within 24 – 48 hours occurred in 79 (79%) and 90 patients (90%) from the study group, respectively, compared with 38 (63%) and 44 patients (73%) from the control group, respectively. The presence of NSR at discharge was achieved in 98 study patients (98%) and 50 control patients (83%). There was no significant difference with regard to the outcome between the two categories (ie, digoxin/procainamide and diltiazem) in the control group. Patients who remained in AF at the time of discharge were placed on anticoagulation. The need for electrical CVN in an effort to restore NSR was necessary in 10 patients from the study group. The length of stay (LOS) for study and control patients was 7.4 and 9.1 days, respectively (Table 2). There was no mortality in either group. The incidence of adverse events was similar in both groups (Table 3). There was no need for transesophageal echocardiography (TEE) in the study group. Five patients in the control group underwent TEE before electrical CVN. Lastly, 2 patients (2%) in the study group required anticoagulation for persistent AF, whereas 10 patients (17%) required anticoagulation in the control group. At 1 month after release, 2 out of 58 study patients (3.4%) discharged with NSR required readmission for recurrent AF and 8 out of 90 control patients (8.9%) discharged with NSR required readmission for recurrent AF. At 1 month after discharge, all of the study patients and 7 of the 10 control patients who were discharged with AF on anticoagulation were experiencing NSR at this time frame.
Comment The incidence rate of postoperative AF in cardiac surgery ranges between 20%–50% [1]. Despite initial enthusiasm regarding a reduction in postoperative AF regarding off-pump CABG [2], subsequent reports cite similar rates for CABG performed with CPB [3]. This study occurred during a period in which all CABG procedures were performed with CPB (ie, on-pump) with standard protocols for perioperative management by a single surgeon. Therefore variables with regard to technique, style, and therapy were kept minimal. In a similar fashion a single
115
type of -blocker (ie, metoprolol) at a fixed dose (ie, 25 mg by mouth [PO] BID) was used to standardize the therapy to avoid outcome differences associated with the numerous types and dosing of the various commercially available -blockers. Efforts to prevent the development of postoperative AF using a multitude of prophylaxis protocols has resulted in varying degrees of success. The use of prophylactic amiodarone, for example, has been well-documented, with postoperative AF occurring in as low as 5% [4, 5] to as high as 35% [6] of the study patients. Several other studies administered amiodarone as the agent of choice with regard to prophylaxis [7–10] and have reported differing outcomes depending upon the patient population, the route of drug administration, the duration of drug administration, and the presence or absence of -blocker therapy. In this study amiodarone was used selectively with the overall goal of establishing NSR within 24 hours. Irrespective of preoperative medications, all patients received -blocker therapy thus minimizing the effects of “-blocker withdrawal” on outcome. In an effort to approach the problem from another perspective, our goal was to compare a traditional strategy of treatment (ie, digoxin and procainamide or diltiazem) with a new protocol using a combination of IV and oral amiodarone selectively. The rational for the protocol was based on the observation of two separate studies using IV amiodarone [6] and oral amiodarone [11] prophylactically. Although both studies indicated efficacy compared with the control groups, the incidence of AF was still significant—25% and 35%. In contrast to these studies and others investigations, we added the component of early electrical CVN at the 48-hour mark to avoid the necessity for anticoagulation. Although there is no established necessity for anticoagulation after 48 hours regarding heart surgery patients in whom AF developed, the common practice is to, nonetheless, institute heparin and coumadin therapy to avoid stroke. Thus the goal of our investigation was to determine if NSR could be accomplished within 48 hours of the onset of postoperative AF to restore the postoperative course of the patient as though the arrhythmia never occurred. Compared with the original management using digoxin and procainamide or diltiazem, the study patients demonstrated superior conversion rates at all time intervals. Furthermore the use of early electrical CVN obviated the necessity for anticoagulation and TEE. Although it was our observation that this study protocol was responsible for a decrease in the average LOS by nearly 36 hours, the small study size did not indicate statistical significance. The average LOS for contemporaneous CABG patients without the development of postoperative AF was comparable with the study group at 7.5 days. The average LOS for non-AF patients did not change significantly during the entire study period. Although a financial analysis was not performed with regard to this research, the reduced LOS as well as the avoidance of TEE and anticoagulation suggests that a cost decrease would exist.
CARDIOVASCULAR
Ann Thorac Surg 2005;79:113– 6
CARDIOVASCULAR
116
SAMUELS ET AL AMIODARONE FOR POSTOPERATIVE AF
There are several limitations inherent to this study, including a relatively small sample size and limited follow-up. Although this was a retrospective, nonrandomized, nonblinded, and historically controlled review the data supports a favorable response with regard to the use of amiodarone as a superior antiarrhythmic therapy to treat postoperative AF and the role of early CVN to restore NSR. This combination of pharmacological and electrical therapies results in a LOS equivalent to those patients who never experienced postoperative AF. In conclusion the use of amiodarone and early electrical CVN is a safe, practical, and efficacious approach to the CABG patient in whom postoperative AF often develops. Selective pharmacologic treatment in combination with selective electrical therapy, as opposed to prophylactic treatment, may obviate the unnecessary and, thus far, ineffective prophylaxis regimens.
References 1. Burke SW, Solomon AJ. Atrial fibrillation in patients after cardiovascular surgery : incidence, risk factors, preventive and therapeutic strategies. Am J Cardiovasc Drugs 2003;3: 95–100. 2. D’Amato TA, Savage EB, Wiechmann RJ, Sakert T, Benckart DH, Magovern JA. Reduced incidence of atrial fibrillation with minimally invasive direct coronary artery bypass. Ann Thorac Surg 2000;70:2013– 6.
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