© 2005 The European Society of Cardiology. Published by Elsevier Ltd. All rights reserved.
OPINION
Have all the ICD primary prevention trials excluded an important group of patients?
The Cardiac Arrhythmia Service, Lahey Medical Center Burlington, Massachusetts, USA
Manuscript submitted 20 July 2004. *Corresponding author. Department of Cardiology, 41 Mall Road, Burlington, MA 01805, USA. Tel.: +1 781 744 8863. E-mail address: david.t.martin{at}lahey.org
Abstract
Primary prevention trials of implantable cardioverter defibrillator (ICD) therapy have generally excluded patients early after revascularization. Clinicians are commonly faced with patients who have ventricular dysfunction and nonsustained ventricular tachyarrhythmia developing shortly after revascularization. Since there are no evidence-based guidelines, management is currently at the discretion of the treating clinician. Recently, evidence has emerged that this patient population is at increased risk of development of life-threatening ventricular tachyarrhythmia and, pending prospective trials, we suggest that ICD therapy should be used in appropriately selected patients with perioperative ventricular arrhythmia.
Key Words: implantable cardioverter defibrillator, cardiac surgery, ventricular tachyarrhythmia
Randomized controlled trials of ICD therapy have greatly improved our knowledge about sudden death reduction in patients with ventricular dysfunction. Both primary and secondary prevention trials have shown significant reduction in mortality in this patient population. The benefit is marked when the ventricular dysfunction is due to coronary artery disease, and recent evidence [1,
2] suggests that patients with idiopathic cardiomyopathy also benefit.
The MUSTT trial [3] evaluated patients with ischaemic cardiomyopathy (left ventricular ejection fraction 
40%) and asymptomatic nonsustained ventricular tachycardia who had sustained tachycardia induced during programmed ventricular stimulation; the risk of cardiac arrest or death from arrhythmia among the patients who received an ICD was significantly lower than that among the patients discharged without receiving one. The MADIT II trial [4] evaluated patients with prior myocardial infarction and a left ventricular ejection fraction of 30%; after an average follow-up of 20 months, ICD therapy reduced mortality by 31% compared with conventional therapy. SCD-HeFT [2] evaluated patients with ischaemic and nonischaemic cardiomyopathy with ejection fraction 35%; after a median of 45.5 months of follow-up, ICD therapy reduced mortality by 23% compared with placebo or amiodarone therapy.
In clinical practice, most ICD recipients are similar to the patients who were enrolled in these trials; however, some have characteristics that were not studied. Electrophysiologists are commonly asked to see patients with ventricular dysfunction that develop nonsustained ventricular tachyarrhythmia (nsVT) immediately after surgical and percutaneous revascularization. There are no guidelines addressing this patient population and the decision on how to proceed is dependent on the discretion of the treating electrophysiologist. All primary prevention trials excluded patients early after revascularization. The SCD-HeFT trial [2] excluded patients within 1 month of coronary bypass surgery; the MADIT II trials [4] excluded patients within the first 3 months of revascularization; in the MUSTT trial [3] most patients who were included were revascularized many months before recognition of nsVT (nsVT/VT). The rationale for exclusion of this patient population is dual: ventricular function often improves after revascularization [5], thus reducing the risk of sudden cardiac death; and recent cardiac surgery may increase the risk of nsVT [6].
We have recently studied 97 patients who had an ICD implanted in our institution for perioperative nsVT or VT during the index admission for cardiac bypass surgery over the past 10 years. Forty-four of these patients had an ICD implanted for de novo postoperative nsVT/VT [7]. The mean age (±SD) was 66 ± 11 years and 91% were males. The preoperative ejection fraction was 32 ± 10% (range 15–60%). The nsVT/VT occurred 4 ± 3 days after surgery and was nonsustained in 33 patients. The patients were mostly in sinus rhythm (95%) before the occurrence of the arrhythmia. Eleven patients (25%) developed sustained postoperative VT; this group was implanted without having programmed ventricular stimulation, whereas the rest (33 patients) who had nonsustained VT underwent ICD implantation after a positive stimulation test (sustained monomorphic VT in 91%). Patients received appropriate medical therapy for the nsVT before undergoing programmed ventricular stimulation. ICDs were implanted 8 ± 5 days after the surgery. During a mean follow-up of 41 ± 27 months, seven patients had appropriate therapy. Four of the 33 patients (12%) who had nsVT and three of the 11 (27%) who had sustained VT had therapy (P = NS). Four patients had appropriate therapy in the first month. There were five deaths (11%) during the follow-up period. This striking benefit of ICD therapy in selected patients early after cardiac surgery has recently been confirmed by other investigators [8,9].
This recent retrospective research has suggested that ICD implantation for postoperative nsVT/VT during the index admission for cardiac surgery is beneficial, since there is a high rate of early recurrence. This patient population has been excluded from previously conducted prospective ICD trials, but is deserving of further scrutiny because of the high frequency of postoperative nsVT/VT. Our study showed that four patients (9%) had appropriate ICD therapy in the first month after implant; arranging a follow-up consultation with an electrophysiologist 1–2 months after cardiac surgery may therefore be a high risk strategy.
In conclusion, there is a lack of clear management guidelines in patients immediately after cardiac surgery and revascularization. The ACC/AHA/NASPE guidelines for implantation of antiarrhythmia devices [10] do not address this patient population. Our research [7] and that of others [8,9] suggests that these patients should be included in prospective randomized clinical trials and they should be included in future updates of these guidelines.
References
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[2] Bardy GH, Lee KL, Mark DB, et al. Amiodarone or an implantable cardioverter-defibrillator for congestive heart failure. N Engl J Med 2005; 352: 225–237.
[3] Buxton AE, Lee KL, Fisher JD, Josephson ME, Prystowsky EN, Hafley G. A randomized study of the prevention of sudden death in patients with coronary artery disease Multicenter Unsustained Tachycardia Trial Investigators. N Engl J Med 1999; 341: 1882–1890.
[4] Moss AJ, Zareba W, Hall WJ, et al. Prophylactic implantation of a defibrillator in patients with myocardial infarction and reduced ejection fraction. N Engl J Med 2002; 346: 877–883.
[5] Gunning MG, Chua TP, Harrington D, et al. Hibernating myocardium: clinical and functional response to revascularisation. Eur J Cardiothorac Surg 1997; 11: 1105–1112.[Abstract]
[6] Brembilla-Perrot B, Villemot JP, Carteaux JP, et al. Postoperative ventricular arrhythmias after cardiac surgery: immediate- and long-term significance. Pacing Clin Electrophysiol 2003; 26: 619–625.[CrossRef][Medline]
[7] Bolad I, MacLellan C, Karanam S, et al. Effectiveness of early implantation of cardioverter defibrillator for postoperative ventricular tachyarrhythmia. Am J Cardiol 2004; 94: 376–378.[Medline]
[8] Telfer EA, Mecca A, Martini M, Olshansky B. Implantable defibrillator use for de novo ventricular tachyarrhythmias encountered after cardiac surgery. Pacing Clin Electrophysiol 2002; 25: 951–956.[Medline]
[9] Mittal S, Lomnitz DJ, Mirchandani S, et al. Prognostic significance of nonsustained ventricular tachycardia after revascularization. J Cardiovasc Electrophysiol 2002; 13: 342–346.[CrossRef][Web of Science][Medline]
[10] Gregoratos G, Abrams J, Epstein AE, et al. ACC/AHA/NASPE 2002 guideline update for implantation of cardiac pacemakers and antiarrhythmia devices: summary article: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (ACC/AHA/NASPE Committee to update the 1998 Pacemaker Guidelines). Circulation 2002; 106: 2145–2161.
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