CORRESPONDENCE: LETTER TO THE EDITOR
Implantable Cardioverter-Defibrillator Shocks and Their Adverse Impact on Patient-Centered Outcomes: Fact or Fiction?
Susanne S. Pedersen, PhD* and
Krista C. van den Broek, MA
* CoRPS, Department of Medical Psychology, Room P506, Tilburg University, Warandelaan 2, P.O. Box 90153, 5000 LE Tilburg, the Netherlands (Email: s.s.pedersen{at}uvt.nl).
In a recent issue of the Journal, Daubert et al. (1) reported the impact of inappropriate implantable cardioverter-defibrillator (ICD) shocks on health outcomes in the MADIT II (Multicenter Automatic Defibrillator Trial II). The incidence of 1 or more inappropriate shocks was 11.5%, inappropriate shocks comprised 31.2% of all shock episodes, and inappropriate shocks predicted a 2-fold increased mortality risk. In their conclusions, the authors refer to the potential detrimental effects of inappropriate shocks on quality of life but also state that this association is not yet established. In an accompanying editorial, Dr. Raitt (2) also refers to the effect of shocks on patient-centered outcomes such as quality of life and psychological distress.
However, the majority of references cited to substantiate this impact of shocks on patient-centered outcomes were published more than a decade ago (3–6). What is more, neither Daubert et al. (1) nor Raitt (2) cite any studies that failed to find a relationship between shocks and patient-centered outcomes, although these data are available (7–12). Differences in study design and the way that shocks were assessed (e.g., self-report vs. objectively measured) and quantified (e.g., shocks/no shocks vs. number of shocks) may in part explain these mixed findings. For example, in the Canadian Implantable Defibrillator Study there was a dose-response relationship, with only patients experiencing  5 shocks being at risk for impaired quality of life (13).
Alternatively, the inconsistency in findings may be attributed to whether factors that may potentially compete with shocks as a determinant of outcome were accounted for. Sears et al. (14) showed that although shocks had a significant effect on quality of life, this effect was relatively small compared with that of psychological factors such as optimism, trait-anxiety, history of depression, and social support. We showed that device-related concerns and Type D personality (i.e., tendency to experience negative emotions and to inhibit self-expression) had a greater effect on anxiety and depression after ICD implantation compared with shocks (15). In another study, we found that anxiety and depression levels were higher in nonshocked Type D patients than in shocked non–Type D patients, indicating that personality factors may play a substantial role in this context (9).
Taken together, it seems fair to conclude that research on shocks and patient-centered outcomes has produced inconsistent findings and that other factors may be equally (or even more) important in predicting these outcomes after ICD implantation. With changes in ICD programming and the use of new antitachycardia pacing therapies (16) leading to a reduction in shocks and better quality of life (17), it may be time for a paradigm shift that includes looking at the role of other factors in addition to shocks. The ICD shocks may indeed be a "double-edged sword" in terms of their adverse impact on prognosis (2), but their impact on patient-centered outcomes may be more benign than generally assumed. From a clinical perspective, this observation does not imply that shocks are not important in terms of patient-centered outcomes, but rather that the ICD patient's psychological profile is of major importance.
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1. Daubert JP, Zareba W, Cannorm, et al. MADIT II Investigators Inappropriate implantable cardioverter-defibrillator shocks in the MADIT II study: frequency, mechanisms, predictors, and survival impact J Am Coll Cardiol 2008;51:1357-1365.[Abstract/Free Full Text]2. Raitt MH. Implantable cardioverter-defibrillator shocks: a double-edged sword? J Am Coll Cardiol 2008;51:1366-1368.[Free Full Text] 3. Fricchione GL, Olson LC, Vlay SC. Psychiatric syndromes in patients with the automatic internal cardioverter defibrillator: anxiety, psychological dependence, abuse, and withdrawal Am Heart J 1989;117:1411-1414.[CrossRef][Web of Science][Medline] 4. Dunbar SB, Warner CD, Purcell JA. Internal cardioverter defibrillator device discharge: experiences of patients and family members Heart Lung 1993;22:494-501.[Web of Science][Medline] 5. Luderitz B, Jung W, Deister A, Manz M. Patient acceptance of implantable cardioverter defibrillator devices: changing attitudes Am Heart J 1994;127:1179-1184.[CrossRef][Web of Science][Medline] 6. Dougherty CM, Shaver JF. Psychophysiologial responses after sudden cardiac arrest during hospitalization Appl Nurs Res 1995;8:160-168.[CrossRef][Web of Science][Medline] 7. Duru F, Buchi S, Klaghofer R, et al. How different from pacemaker patients are recipients of implantable cardioverter-defibrillators with respect to psychosocial adaptation, affective disorders, and quality of life? Heart 2001;85:375-379.[Abstract/Free Full Text] 8. Newman DM, Dorian P, Paquette M, et al. Effect of an implantable cardioverter defibrillator with atrial detection and shock therapies on patient-perceived, health-related quality of life Am Heart J 2003;145:841-846.[CrossRef][Web of Science][Medline] 9. Pedersen SS, Van Domburg RT, Theuns DAMJ, Jordaens L, Erdman RAM. Type D personality is associated with increased anxiety and depressive symptoms in patients with an implantable cardioverter defibrillator and their partners Psychosom Med 2004;66:714-719.[Abstract/Free Full Text] 10. Pedersen SS, Theuns DA, Muskens-Heemskerk A, Erdman RA, Jordaens L. Type-D personality but not implantable cardioverter-defibrillator indication is associated with impaired health-related quality of life 3 months post-implantation Europace 2007;9:675-680.[Abstract/Free Full Text] 11. Groeneveld PW, Matta MA, Suh JJ, Yang F, Shea JA. Quality of life among implantable cardioverter-defibrillator recipients in the primary prevention therapeutic era Pacing Clin Electrophysiol 2007;30:463-471.[CrossRef][Medline] 12. Van den Broek KC, Nyklicek I, Van der Voort PH, Alings M, Denollet J. Shocks, personality, and anxiety in patients with an implantable defibrillator Pacing Clin Electrophysiol 2008;31:850-857.[CrossRef][Medline] 13. Irvine J, Dorian P, Baker B, et al. CIDS Investigators Quality of life in the Canadian Implantable Defibrillator Study (CIDS) Am Heart J 2002;144:282-289.[Web of Science][Medline] 14. Sears SF, Lewis TS, Kuhl EA, Conti JB. Predictors of quality of life in patients with implantable cardioverter defibrillators Psychosomatics 2005;46:451-457.[Abstract/Free Full Text] 15. Pedersen SS, Theuns DAMJ, Erdman RAM, Jordaens L. Clustering of device-related concerns and type D personality predicts increased distress in ICD patients independent of shocks Pacing Clin Electrophysiol 2008;31:20-27.[Medline] 16. Wathen M. Implantable cardioverter defibrillator shock reduction using new antitachycardia pacing therapies Am Heart J 2007;153(Suppl):44-52.[CrossRef][Medline] 17. Wathen M, DeGroot P, Sweeney MO, et al. PainFree RX II Investigators Prospective randomized multicenter trial of empirical antitachycardia pacing versus shocks for spontaneous rapid ventricular tachycardia in patients with implantable-cardioverter defibrillators: pacing fast ventricular tachycardia reduces shock therapies (PainFree RX II) trial results Circulation 2004;110:2591-2596.
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