Are Eligible Patients in the Community Receiving ICDs?
Abstract & Commentary
Edward P. Gerstenfeld, MD Professor of Medicine, Chief, Cardiac Electrophysiology, University of California, San Francisco
Source: Narayanan K, et al. Frequency and determinants of implantable cardioverter defibrillator deployment among primary prevention candidates with subsequent sudden cardiac arrest in the community. Circulation 2013;128:1733-1738.
Sudden death accounts for 50% of cardiovascular mortality, and implantation of implantable cardioverter defibrillators (ICD) may be underutilized. The Oregon Sudden Unexpected Death Study is a community-based, prospective study of sudden cardiac arrest (SCA). The study has tracked all SCA in the Portland area since 2003. In the current study, all SCA survivors ≥ 18 years of age who had an echocardiogram prior to cardiac arrest were included. The records were reviewed to determine who was eligible for an ICD prior to the cardiac arrest, and who had and did not have an ICD placed according to the time-period appropriate guidelines based on the MADIT-II1 and SCD-HeFT2 studies. Patients who had a secondary prevention ICD (i.e., for pre-existing ventricular tachycardia or fibrillation) in place before the SCA, with echocardiograms performed within 40 days of an acute coronary event, or with expected survival < 1 year were excluded.
There were a total of 2093 SCAs identified between 2003 and 2012, and of these, 488 patients had a prior qualifying echocardiogram. Of these, 144 (32.1%) had LVEF ≤ 35%, 127 (28.3%) had LVEF ≤ 30%, and 304 (67.9%) had LVEF > 35%. According to time-specific guideline criteria, there were 12 primary ICD implantations among the 92 eligible candidates (13%). In addition, there were three primary prevention ICDs implanted during 2003-2005 that did not meet MADIT II criteria, increasing the primary ICD implantation rate to 15 of 95 (15.8%). Those not receiving ICDs were older than those receiving ICDs (age 67.1 ± 13.6 vs 58.5 ± 14.8 years; P = 0.05); there were no ICD recipients among those aged ≥ 80 years, while 16 (20%) of the nonrecipients were ≥ 80 years (P = 0.11). There were no significant differences in sex, race, history of myocardial infarction, or revascularization before SCA between the ICD recipients and nonrecipients. All recipients and a majority of the nonrecipients had a clinical history of heart failure. Ten (83.3%) and 61 (76.3%) of recipients and nonrecipients, respectively, were on diuretics for symptomatic heart failure. Among ICD nonrecipients, 13.8% had dementia, 12.5% were on chronic dialysis, 25% had peripheral vascular disease (PVD), and 11.3% had diabetes mellitus. The authors concluded that a community survey of sudden cardiac arrest victims showed that 20% were eligible for prophylactic ICD implantation, but only a small proportion of these had ICDs. These data suggest that further study of the barriers to primary prevention ICD implantation is warranted.
Commentary
In this community-based study of cardiac arrest survivors, nearly one-third had a prior echocardiogram with an EF < 35%. Yet, only 15% had a primary prevention ICD implanted. The majority (> 2/3) of patients were on chronic heart failure therapy, including diuretics, suggesting clinical heart failure symptoms. The time between the qualifying echocardiogram and the cardiac arrest was on average > 2 years, suggesting that the reduced ejection fraction was not a recent diagnosis in these patients. Why was the utilization of ICDs so low in this population? Some of the nonrecipients were older (20% > age 80) and had comorbidities such as chronic dialysis (12.5%) or dementia (13.8%). I think most would agree that an elderly patient with dementia or on chronic dialysis would not benefit from an ICD. However, most studies have shown that the rate of appropriate ICD shocks is similar in the elderly to younger patients, and that age alone should not be an exclusion to ICD placement.3 Many physicians in the community have become disillusioned with ICDs due to problems with lead failures, inappropriate shocks, and lack of perceived benefit. It is important to recall that in the SCD-HeFT trial,2 the mortality benefit in primary prevention ICD recipients was 7% over 5 years — thus one would need to follow 100 patients with implanted ICDs for 5 years to see seven lives saved.
The current study certainly has limitations — we cannot appreciate the number of patients who received ICDs during this time period who may have benefitted, and the clinical scenario of each patient is difficult to determine. In general, I believe we have all learned that ICD placement is a careful decision that involves risks and benefits that need to be considered and discussed with each patient. However, we should remember that the mortality benefit with ICD placement is greater than many commonly prescribed medical therapies. The finding in this study that < 10% of SCA patients survived to hospital discharge is disconcerting. If nothing else, this study should serve as a wake-up call to remember to consider ICD placement in the appropriate patient with reduced ejection fraction. In the future, better risk stratification tools and predictors of SCA are sorely needed.
References
- Moss AJ, et al. Prophylactic implantation of a defibrillator in patients with myocardial infarction and reduced ejection fraction. N Engl J Med 2002;346:877-883.
- Bardy GH, et al. Amiodarone or an implantable cardioverter-defibrillator for congestive heart failure. N Engl J Med 2005;352:225-237.
- Yung D, et al. Survival after implantable cardioverter-defibrillator implantation in the elderly. Circulation 2013;127:2383-2392.
