Europace Advance Access originally published online on November 13, 2006
Europace 2006 8(12):1054-1056; doi:10.1093/europace/eul123
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
ICD
Influence of gender on ICD implantation for primary and secondary prevention of sudden cardiac death
Division of Cardiology, University of Ottawa Heart Institute, H145-1053 Carling Avenue, Ottawa, Ontario, Canada K1Y 4E9
Manuscript submitted 15 January 2006. Accepted after revision 20 August 2006.
* Corresponding author: Tel.: +1 613 761 4914; fax: +1 613 761 4407. E-mail address: dbirnie{at}ottawaheart.ca
 |
Abstract |
|---|
 Top Abstract IntroductionResultsDiscussionReferences |
|---|
Aims This study sought to investigate the influence of gender on access to ICD therapy and examine the influence of gender on subsequent ICD shock experience.
Methods and results The records of 353 consecutive patients (140 and 213 secondary prevention, respectively) who received their first ICD between January 2000 and March 2004 were reviewed. All patients fulfilled criteria for primary or secondary prevention ICD implantation. Baseline characteristics and ICD shock experiences were compared. Female patients were younger and less likely to have a history of ischaemic heart disease or atrial arrhythmias (P<0.01). In contrast, female patients were more likely to have heart failure and diabetes (P<0.01). Markedly fewer females received an ICD for either primary (M:F ratio 8.5:1, P<0.01) or secondary (M:F ratio 4.5:1, P<0.01) prevention. Further, significantly fewer female patients received an ICD for MADIT II indications (M:F 11.2:1, P<0.01). Over the mean follow-up of 1.8±1.1 years, gender had no influence upon the likelihood of receiving either an appropriate or an inappropriate shock (P=ns).
Conclusion Although male patients accounted for the great majority (85%) of all ICD recipients, there was no evidence of influence of gender on the likelihood of receiving an appropriate or inappropriate shock.
Key Words: Arrhythmias, Implantable cardioverter defibrillators, Gender, Sudden cardiac death
|
Introduction |
|---|
|
TopAbstractIntroductionResultsDiscussionReferences |
|---|
Despite advances in cardiovascular care, sudden cardiac death remains a major public health issue. Early Framingham data showed that women have a lower incidence of sudden cardiac death (M:F age-adjusted excess of 2:1) with events lagging 10–20 years behind those in men.1
More recent reports would suggest that this rate more closely approximates 1.3–1.4:1.2
Two previous studies have examined the influence of gender upon ICD implantation practices.3,4 These studies predominantly examined secondary prevention of sudden cardiac death (<5% of patients were implanted for primary prevention). The aim of this study was to examine the influence of gender on ICD implantation for primary and secondary prevention of sudden cardiac death. In addition, the study examined the effect of gender on subsequent shock experience.
Methods
This observational study was conducted on all consecutive patients who underwent first ICD implantation from January 2000 to March 2004 at a Canadian tertiary care centre. All patients fulfilled criteria for primary or secondary prevention ICD implantation. Early ICD recipients were implanted largely for secondary prevention following aborted sudden cardiac death or VT. With the publication of large primary prevention trials such as MUSST,5 MADIT,6 MADIT II,7 and SCD-HeFT,8 an increasing proportion of patients were implanted for primary prevention.
Baseline and follow-up data were entered prospectively in the ICD clinic database. Additional data were collected from ICD follow-up notes, office notes, and computer records. Information was collected on demographics, past medical history, type of ICD implant, and ICD interrogation results. The follow-up period began following ICD implantation and ended in March 2004. In the first year, patients were followed in the ICD clinic at 3-month intervals and thereafter on a semi-annual basis.
All identified shocks were reviewed independently by two experienced clinical electrophysiologists in a blinded fashion. Appropriate shocks were defined as shocks delivered during VF/VT.
Data are presented as mean±SD. Analysis of variance between and within groups was done through a simple unpaired and paired Student's t-test, respectively. Categorical variables were analyzed using a 
2 test. Kaplan–Meier analysis was performed for endpoints of total shocks and ICD implantation indication.
|
Results |
|---|
|
TopAbstractIntroductionResultsDiscussionReferences |
|---|
Data were collected from 353 consecutive patients (85% male; age 63±13 years) who underwent first ICD implantation from January 2000 to March 2004. One hundred and forty-three patients received ICDs for primary prevention and 210 patients for secondary prevention (Table 1). Follow-up was similar between the two genders (1.8±1.1 vs. 1.7±1.2 years, P=ns). Female patients were significantly younger than male patients (57±14 vs. 64±12 years, P<0.01) and less likely to have a history of ischaemic heart disease (56 vs. 64%, P<0.01), myocardial infarction (45 vs. 69%, P<0.01), coronary artery bypass grafting (21 vs. 35%, P<0.01), or atrial arrhythmias (17 vs. 29%, P<0.01). Female patients were more likely than male patients to have a history of heart failure (33 vs. 25%, P<0.01) and diabetes (28 vs. 20%, P<0.01). The genders had similar baseline left ventricular ejection fraction (LVEF) (28±11 vs. 26±10%, P=ns).
|
Markedly fewer females received an ICD for either primary (15 vs. 128 patients, M:F ratio 8.5:1, P<0.01) or secondary (38 vs. 172 patients, M:F ratio 4.5:1, P<0.01) prevention. Further, significantly fewer female patients received an ICD for MADIT II7
indications (9 vs. 101, M:F 11.2:1, P<0.01). When comparing the baseline characteristics of patients who received an ICD for primary prevention, there were no significant predictors between the genders. During clinical follow-up (1.8±1.1 years), 10 (19%) of the female patients received an appropriate shock (Figure 1) and 57 (19%) of the male patients received a shock over the follow-up period (P=ns when compared with female).
|
|
Discussion |
|---|
|
TopAbstractIntroductionResultsDiscussionReferences |
|---|
This study examines the influence of gender upon ICD implantation for primary and secondary prevention of SCD. Markedly fewer females received ICDs for both primary and secondary prevention. This finding is similar to two previous clinical series which have examined the influence of gender upon ICD implantation practice for secondary prevention of sudden cardiac death.3
,4 These authors found no evidence of in-house discrimination and speculate that women were not implanted due to referral bias.4
Our series is the first to examine the influence of gender in a large group of primary prevention patients. Our findings indicate an even greater gender disparity for these patients (especially MADIT II patients, M:F ratio 11.2:1). This finding was independent of other baseline characteristics, such as age, LVEF, and medical history. Data from various sources suggest that the M:F ratio of primary prevention ICD candidates is between 1.9:1 and 2.7:1.9–11
It is possible that females are not undergoing primary prevention ICD implantation through initial referral bias or unwillingness to undergo ICD implantation. The latter may play a role as females present later in life with ischaemic cardiomyopathy, and investigators have suggested that individual preference for life-sustaining therapies decreases with increasing age.12 In addition, several studies have consistently shown that males exhibit a greater interest in life-sustaining treatments.12 However, it seems more likely that the major factor is referral bias rather than refusal, as women tend to present later with heart disease and hence the female cohort should be older and not younger.
Despite a sex bias in ICD implantation, the subsequent shock experience was similar between the genders. These data extend findings from previous reports in secondary prevention populations.3,4
This study showed that among a contemporary cohort, male patients accounted for the great majority (85%) of all ICD recipients. This gender difference was even more marked for primary prevention ICD implants. There was no evidence of influence of gender on the likelihood of receiving an appropriate shock.
|
References |
|---|
|
TopAbstractIntroductionResultsDiscussionReferences |
|---|
[1] Kannel WB, Wilson PW, D'Agostino RB, Cobb J. Sudden coronary death in women. Am Heart J 1998; 136: 205–12.[CrossRef][Web of Science][Medline]
[2] Abildstrom SZ, Rask-Madsen C, Ottesen MM, Andersen PK, Rosthoj S, Torp-Pedersen C, et al. Impact of age and sex on sudden cardiovascular death following myocardial infarction. Heart 2002; 88: 573–8.
[3] Pires LA, Sethuraman B, Guduguntla VD, Todd KM, Yamasaki H, Ravi S. Outcome of women versus men with ventricular tachyarrhythmias treated with the implantable cardioverter defibrillator. J Cardiovasc Electrophysiol 2002; 13: 563–8.[CrossRef][Web of Science][Medline]
[4] Staniforth AD, Sporton SC, Robinson NM, Cooper J, Earley MJ, Nathan AW, et al. Is there a sex bias in implantable cardioverter-defibrillator referral and prescription? Heart 2004; 90: 937–8.
[5] 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: 1882–90.
[6] Moss AJ, Hall WJ, Cannom DS, Daubert JP, Higgins SL, Klein H, et al. Improved survival with an implanted defibrillator in patients with coronary disease at high risk for ventricular arrhythmia. Multicenter Automatic Defibrillator Implantation Trial Investigators. N Engl J Med 1996; 335: 1933–40.
[7] Moss AJ, Zareba W, Hall WJ, Klein H, Wilber DJ, Cannom DS, et al. Prophylactic implantation of a defibrillator in patients with myocardial infarction and reduced ejection fraction. N Engl J Med 2002; 346: 877–83.
[8] Bardy GH, Lee KL, Mark DB, Poole JE, Packer DL, Boineau R, et al. Amiodarone or an implantable cardioverter-defibrillator for congestive heart failure. N Engl J Med 2005; 352: 225–37.
[9] McDonagh TA, Morrison CE, Lawrence A, Ford I, Tunstall-Pedoe H, McMurray JJ, et al. Symptomatic and asymptomatic left-ventricular systolic dysfunction in an urban population. Lancet 1997; 350: 829–33.[CrossRef][Web of Science][Medline]
[10] Gauri AJ, Davis A, Hong T, Burke MC, Knight BP. Disparities in the use of primary prevention and defibrillator therapy among blacks and women. Am J Med 2006; 119: 167–21.
[11] Al Khatib SM, Anstrom KJ, Eisenstein EL, Peterson ED, Jollis JG, Mark DB, et al. Clinical and economic implications of the Multicenter Automatic Defibrillator Implantation Trial-II. Ann Intern Med 2005; 142: 593–600.
[12] Ditto PH, Smucker WD, Danks JH, Jacobson JA, Houts RM, Fagerlin A, et al. Stability of older adults' preferences for life-sustaining medical treatment. Health Psychol 2003; 22: 605–15.[CrossRef][Web of Science][Medline]
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  D. H. Birnie MB ChB MD, C. Sambell BSc, H. Johansen PhD, K. Williams MS, R. Lemery MD, M. S. Green MD, M. H. Gollob MD, D. S. Lee MD PhD, and A. S.L. Tang MD Use of implantable cardioverter defibrillators in Canadian and US survivors of out-of-hospital cardiac arrest Can. Med. Assoc. J., July 3, 2007; 177(1): 41 - 46. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||