Letter by Witte et al Regarding Article, “Implantable Cardioverter-Defibrillators in Tetralogy of Fallot”
To the Editor:
Khairy et al1 are to be commended for their presentation of data examining the effects of implantable cardioverter-defibrillators (ICDs) in patients with tetralogy of Fallot. The management of the risk of sudden cardiac death in such patients remains a major problem for the physicians caring for patients with congenital heart disease (CHD). We feel, however, that enthusiasm for ICD therapy in CHD should be tempered by the current lack of evidence of absolute benefit and clear evidence of device-related physical and psychological morbidity.
ICDs are recommended in patients with repaired CHD in both North America and Europe.2 The guideline that presented this recommendation is not based on randomized studies. Patients with CHD have a lower overall rate of death than do patients with both ischemic left ventricular dysfunction and dilated cardiomyopathy, and yet even in these groups with relatively higher risk, outstanding questions about the use of ICDs remain. In ischemic heart disease, there is no overall mortality benefit from ICD therapy in patients with more severe heart failure symptoms,3 and the data in dilated cardiomyopathy, with a mean 1-year death rate in the placebo groups of 9%, are even less robust.4 Hence, one has to suspect that unless more refined selection criteria are developed, and the data presented in their highly selected group are not sufficient, the use of ICDs in tetralogy of Fallot patients, who have an annualized sudden cardiac death rate of 1.2% to 1.8%, would be associated with reductions in the rate of death that are more marginal than those seen in ischemic heart disease or dilated cardiomyopathy.
Lack of randomized data showing a reduction in the rate of death with ICD therapy in CHD is not the only reason to be cautious. Although 24% of their1 primary and 30% of their secondary prevention patients received an appropriate shock from their device for ventricular tachyarrhythmia, it is impossible to determine in a retrospective series whether such discharges were for life-threatening arrhythmias that would have lead to cardiovascular instability or nonsustained non–life-threatening ventricular tachycardia. In patients with dilated cardiomyopathy, such appropriate shocks are not equivalent to life-saving shocks5; therefore, the reported higher shock rates for patients with dilated cardiomyopathy compared with patients with hypertrophic cardiomyopathy or ischemic heart disease should not be taken as equivalent to a higher rate of sudden cardiac death prevention. Furthermore, the complication rate (amounting to 30%) and inappropriate shock rate (almost 6% per year) are higher than in patients with traditional indications. In addition, the late lead complications seen in 25 patients in their group (more than 10%), although infrequently contributing to death, are commonly associated with significant morbidity and prolonged hospital stays.
Although the data presented by Khairy et al1 contribute importantly to the world literature on the question of ICD therapy in tetralogy of Fallot, the issue is by no means resolved. Planning an adequately powered, randomized, placebo-controlled study of ICD therapy in CHD might never be practical. However, the current published guidelines are not evidence based and the significant morbidity impact of ICD implantation in young patients with an overall excellent life expectancy should not be underestimated.
Khairy P, Harris L, Landzberg MJ, Viswanathan S, Barlow A, Gatzoulis MA, Fernandes SM, Beauchesne L, Therrien J, Chetaille P, Gordon E, Vonder Muhll I, Cecchin F. Implantable cardioverter-defibrillators in tetralogy of Fallot. Circulation. 2008; 117: 363–370.
Zipes DP, Camm AJ, Borggrefe M, Buxton AE, Chaitman B, Fromer M, Gregoratos G, Klein G, Moss AJ, Myerburg RJ, Priori SG, Quinones MA, Roden DM, Silka MJ, Tracy C, Blanc JJ, Budaj A, Dean V, Deckers JW, Despres C, Dickstein K, Lekakis J, McGregor K, Metra M, Morais J, Osterspey A, Tamargo JL, Zamorano JL, Smith SC Jr, Jacobs AK, Adams CD, Antman EM, Anderson JL, Hunt SA, Halperin JL, Nishimura R, Ornato JP, Page RL, Riegel B; American College of Cardiology/American Heart Association Task Force; European Society of Cardiology Committee for Practice Guidelines; European Heart Rhythm Association and the Heart Rhythm Society. ACC/AHA/ESC 2006 guidelines for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death–executive summary: a report of the American College of Cardiology/American Heart Association Task Force and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Develop Guidelines for Management of Patients with Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death). Eur Heart J. 2006; 27: 2099–2140.
Bardy GH, Lee KL, Mark DB, Poole JE, Packer DL, Boineau R, Domanski M, Troutman C, Anderson J, Johnson G, McNulty SE, Clapp-Channing N, Davidson-Ray LD, Fraulo ES, Fishbein DP, Luceri RM, Ip JH; Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT) Investigators. Amiodarone or an implantable cardioverter-defibrillator for congestive heart failure. N Engl J Med. 2005; 352: 225–237.
Ellenbogen KA, Levine JH, Berger RD, Daubert JP, Winters SL, Greenstein E, Shalaby A, Schaechter A, Subacius H, Kadish A; Defibrillators in Non-Ischemic Cardiomyopathy Treatment Evaluation (DEFINITE) Investigators. Are implantable cardioverter defibrillator shocks a surrogate for sudden cardiac death in patients with nonischemic cardiomyopathy? Circulation. 2006; 113: 776–782.