Home defibrillation: A feasibility study in myocardial infarction survivors at intermediate risk of sudden death
Article Outline
Abstract
Background
Out-of-hospital cardiac arrest occurs at home in 65-80% of cases and is often witnessed. We designed a study to explore the feasibility of a home defibrillation program (a) evaluating the retention of cardiopulmonary resuscitation and automated external defibrillators (AED) use skills (BLSD) (b) assessing the impact on anxiety, depression, and quality of life and (c) recording the critical issues emerging from program implementation.
Methods
Thirty-three post-myocardial infarction patients and their 56 relatives received BLSD training and an AED. Assessment of BLSD skills, levels of anxiety, and depression and quality of life were scheduled every 3 months for 1 year or until a common stopping date.
Results
Overall BLSD score was 26 ± 3 at baseline vs. 22 ± 5 at 3 months (P < .0001), 21 ± 6 at 6 months (P < .0001), 22 ± 4 at 9 months (P < .0001) and 23 ± 5 at 12 months (P = .001). Conversely, the BLSD component AED use” remained stable throughout the study. Quality of life, anxiety, and depression scores remained constant. Compliance to BLSD retraining sessions and AEDs checks decreased over time and was influenced by a concomitant clinical appoinment.
Conclusions
BLSD performance of families of post-myocardial infarction patients decreases over time, even though the ability to operate AEDs appears to be the least affected component. Compliance with retraining sessions and AED checks declines over time and is improved if they are combined with clinical appointments. The implementation of a home defibrillation program does not affect anxiety, depression, or the quality of life.
Sudden cardiac death is the most frequent cause of death in industrialized countries with an approximated incidence of 1 per 1000 per year, accounting for 14.5% to 20% of fatalities in women and men, respectively.1, 2 Out-of-hospital cardiac arrest (OHCA) occurs at home in 65% to 80% of cases2, 3, 4, 5, 6, 7 and is witnessed in 52% of events to 81% of events,2, 8 often by a family member who attempts cardiopulmonary resuscitation. Ventricular fibrillation and ventricular tachycardia are documented as the presenting rhythm of OHCA1, 6, 8 in up to 70% of cases, although a recent decline down to 41% has been observed.1, 9, 10 The efficacy of automated external defibrillators (AEDs) on the outcome of OHCA caused by ventricular fibrillation or pulseless ventricular tachycardia has been convincingly demonstrated in both experimental and clinical studies and is significantly influenced by time to defibrillation.11 These findings explain the increasing diffusion of AED-based programs both inside and outside the emergency medical system.12 Among programs outside the emergency medical system, a role for home defibrillation (HD) has been proposed, but despite a strong rationale beyond it,13 published evidence of feasibility and efficacy is remote and scant,14, 15, 16, 17, 18, 19, 20, 21 and the awaited results of a large multicenter clinical trial currently under way will not be available in the short term.22
In the year 2001, the use of AEDs by lay persons was allowed across Italy. Following this legislation, we have designed a study to explore the feasibility of an HD program in a population of myocardial infarction survivors at intermediate risk of sudden death. The present article reports the results of our study.
Methods
Aim of the study
The present study was designed to assess the feasibility of an HD program. In this prospective study, the primary objective was to investigate (a) the retention of basic life support and AED use (BLSD) skills; (b) the levels of anxiety and depression; and (c) the quality of life in families of survivors from acute myocardial infarction at intermediate risk of sudden death enrolled in our HD program. The secondary objective of our study was to analyze the critical issues possibly emerging (a) from the presence of an AED at home, (b) from AED use, and (c) from AEDs' periodic checks.
Study design
After the approval of the ethical board of the 4 participating institutions, from April 2003 to September 2005, all patients admitted for ischemic heart disease were screened and considered eligible for HD program if they had an acute myocardial infarction in the previous year, had an ejection fraction of 30% to 40%, were not a candidate for an implantable cardioverter defibrillator (ICD) according to current guidelines,23 had at least one relative trainable to BLSD, and were resident in the study area. The HD program was proposed to eligible patients and their families with the aid of standardized descriptive material. Thirty-three patients and their 59 relatives gave written informed consent and were enrolled in the study.
As previously stated, feasibility of an HD program was investigated through the assessment of BLSD performance (in all relatives and in patients who accepted to be trained), quality of life (in patients), and levels of anxiety and depression (in both patients and relatives); moreover, data about problems possibly arising from the presence of an AED at the patient's home, episodes of AED use, and results of AED technical checks were prospectively collected at the time of follow-up contacts. In detail, enrolled patients and their relatives were interviewed at baseline by a psychologist, completed the 36-item Short-Form (SF-36) questionnaire for the evaluation of quality of life,24, 25 the Zung questionnaires for anxiety26 and depression,27 and received a 2-hour BLSD course based on the International Liaison Committee on Resuscitation (ILCOR) 2000 recommendations28, 29 inclusive of a slide presentation on causes of adult cardiac arrest, basic life support (BLS) techniques (safe approach, initial patient evaluation, emergency call, chest compression, and mouth-to-mouth ventilation), and automated defibrillator use followed by a hands-on training session with AED trainers and BLS manikins. The BLSD training of relatives was a prerequisite for inclusion in the study; however, the opportunity of attending the BLSD course was offered to patients as well. After BLSD course completion, BLSD performance was scored through a dedicated assessment form.30 Observance of safety measures during AED use was required to receive an AED (LIFEPAK 500 AED, Medtronic, Minneapolis, MN). Follow-up contacts to reassess BLSD performance, quality of life, and anxiety and depression profiles; to recall problems arising from the presence of the AED at patient's home; to recall episodes of AED use; and to perform an AED check were scheduled every 3 months for 1 year or until a common stopping date (October 2005). After BLSD performance assessment at follow-up contacts, a retraining session was administered. Clinical follow-up was scheduled at the time of discharge from hospital and thereafter was arranged independently of our study. When a clinical follow-up was independently scheduled in the time window of study follow-up contacts, the opportunity of combining the events was offered.
Statistical analysis
Descriptive statistics were reported using mean and SD for normally distributed continuous variables, or median with 25th to 75th percentile in case of skewed distribution. Normality of distribution was tested by Kolmogorov-Smirnov test for one sample. Absolute and relative frequencies were reported for categorical variables. Comparisons of normally continuous variables were performed by 2-tailed Student t test for 2 distributions and by analysis of variance with Bonferroni correction for >2 distributions. Comparisons of skewed continuous variables were performed by Wilcoxon test for 2 distributions and by Friedman test for >2 distributions. Comparisons of categorical variables were performed by means of Fisher exact test for extreme proportions, or χ2 otherwise. The generalized linear model repeated-measurements test was performed for repeated-measures data. Repeated and difference a priori contrasts were used to test between-subjects factors. SPSS 12.0 software (SPSS Inc, Chicago, IL) was used for statistical analysis.
Results
Eighty-nine persons have been enrolled in the study (33 patients and 56 relatives) from 4 centers. The average age of patients was 66 ± 13 years, 25 (76%) of 33 were males, time from acute myocardial infarction was 2 ± 2 months, and median ejection fraction was 40%35, 36, 37, 38, 39, 40; age of relatives was 45 ± 15 years (P < .0001 as compared to patients) and 27% were males (P < .0001 as compared with patients). Sixty-six persons (10/33 patients and 56/56 relatives) received a formal BLSD course. Of 66 (97%) candidate providers, 64 successfully completed the BLSD course. Conversely, 2 candidate providers repeatedly failed to guarantee the recommended safety measures required to operate an AED and, for the purposes of our study, were considered not suitable as BLSD providers.
Compliance to scheduled BLSD reassessment/retraining session decreased significantly over time. Scheduled BLSD reassessment/retraining sessions were attended by 60 (100%) of 60 trained rescuers at 3 months (P = not significant [NS] vs baseline), 55 (93%) of 59 at 6 months (P = .047 vs baseline, P = NS vs 3 months), 41 (76%) of 54 at 9 months (P = .0001 vs baseline, P = .016 vs 6 months), and 36 (72%) of 50 at 12 months (P = .0001 vs baseline, P = NS vs 9 months) as summarized in Table I. Compliance to study follow-up contacts at 9 months (40/44 with concomitant clinical appointment vs 1/10 without concomitant clinical appointment) and 12 months (32/36 with concomitant clinical appointment vs 4/14 without concomitant clinical appointment) was significantly higher if they were scheduled on the same day of a clinical appointment (P < .0001 at both times).
Table I. Compliance to reassessment/retraining sessions
| Follow-up time (months) | Regularly attended | Scheduled, not attended | Follow-up contact not expired at common stopping date | Dropout |
|---|---|---|---|---|
| 3 | 60 | 0 | 4 | 2 |
| 6 | 55 | 4 | 4 | 3 |
| 9 | 41 | 13 | 9 | 3 |
| 12 | 36 | 14 | 13 | 3 |
Quality of BLSD performance was inferior to baseline at each reassessment (Figure 1). Overall mean BLSD score was 26 ± 3 at baseline versus 22 ± 5 at 3 months (P < .0001), 21 ± 6 at 6 months (P < .0001 as compared with baseline), 22 ± 4 at 9 months (P < .0001 as compared with baseline), and 23 ± 5 at 12 months (P = .001 as compared with baseline). The BLSD performance was analyzed by the following components: evaluation of victims of suspected cardiac arrest, chain of survival activation, cardiopulmonary resuscitation, and finally AED use. Average score for the BLSD component “Evaluation of victims of suspected cardiac arrest” decreased from a median of 6 [4-7] at baseline to 5 [3-6] at 3 months (P < .005), 4 [3-6] at 6 months (P < .01 as compared with baseline), 4 [3-6] at 9 months (P = .03 as compared with baseline), and 5 [3-6] at 12 months (P = .003 as compared with baseline). Average score for the BLSD component “Chain of survival activation” decreased from 7 [5-8] at baseline to 6 [4-6] at 3 months (P = .006), 5 [3-6] at 6 months (P = .009 as compared with baseline), 5 [3-6] at 9 months (P = .052 compared with baseline), and 5 [3-6] at 12 months (P = .002 as compared with baseline). Average score for the BLSD component “Cardiopulmonary resuscitation” decreased from 8 [6-10] at baseline to 7 [5-8] at 3 months (P = .006), 7 [5-8] at 6 months (P = NS as compared with baseline), 7 [5-8] at 9 months (P = NS as compared with baseline), and 8 [5-9] at 12 months (P = NS as compared with baseline). Average score for the BLSD component “AED use” was 6 [4-6] at baseline and remained stable over time: 6 [4-6] at 3 months (P = NS), 5 [4-6] at 6 months (P = NS as compared with baseline), 5 [4-6] at 9 months (P = NS as compared with baseline), and 6 [5-6] at 12 months (P = NS as compared with baseline).
Figure 1.
Scatterplot of individual BLSD scores at follow-up. Significant differences as compared with baseline are evidenced.
Quality of life as perceived by enrolled patients remained stable or even improved over time. Average physical health score as assessed by SF-36 questionnaire was 50 ± 20 at baseline and 52 ± 20, 56 ± 19, 56 ± 23, and 62 ± 23 at 3, 6, 9 and 12 months, respectively (P = .048 at 12 months and P = NS at any other time vs baseline); average mental health score as assessed by SF-36 questionnaire remained unchanged with 54 ± 20 at baseline and 54 ± 18, 58 ± 18, 55 ± 21, and 61 ± 21 at 3, 6, 9 and 12 months, respectively (P = NS at any time vs baseline) (Figure 2, Figure 3).
Figure 2.
Scatterplot of physical quality of life (SF-36) scores at follow-up.
Figure 3.
Scatterplot of mental quality of life (SF-36) scores at follow-up.
Anxiety score in enrolled patients, as assessed by Zung questionnaire, remained stable over time. Anxiety score was 34 ± 6 at baseline as compared with 34 ± 5, 36 ± 7, 37 ± 8, and 35 ± 7 at 3, 6, 9, and 12 months, respectively (P = NS at any time vs baseline). Depression score in enrolled patients, as assessed by Zung questionnaire, remained stable over time. Depression score was 38 ± 8 at baseline as compared with 37 ± 9, 38 ± 7, 40 ± 9, and 39 ± 11 at 3, 6, 9, and 12 months, respectively (P = NS at any other time vs baseline).
Anxiety score in family members of enrolled patients, as assessed by Zung questionnaire, remained stable or was reduced over time. Anxiety score was 34 ± 6 at baseline as compared with 33 ± 7, 34 ± 8, 32 ± 8, and 33 ± 8 at 3, 6, 9 and 12 months, respectively (P = .035 at 3 months and P = NS at any time vs baseline). Depression score in family members of enrolled patients was 34 ± 7 at baseline as compared with 33 ± 7, 34 ± 9, 33 ± 8, and 32 ± 8 at 3, 6, 9, and 12 months, respectively (P = .02 at 3 months and P = NS at any time vs baseline).
During the study period, no error resulting from periodic checks of the AED were reported. Interestingly, the technical assistance request icon on one device was active at a follow-up contact, but it had not been noticed by the enrolled family, thus generating the possibility of a device malfunction in case of AED use.
No cardiac arrest or attempts to AED use were observed in the study period.
Discussion
Despite a strong rationale supporting HD, it has not been largely investigated. Our study expands the previous knowledge about “home defibrillation” with several findings. The first relevant finding of the present study is that families enrolled in an HD program, despite their unique motivation, formal BLSD training, and an intensive intention-to-treat retraining strategy, exhibited a significant decay in all components of BLSD performance except for AED use, which remained unaltered over time. The observed decline in knowledge and skills was expected, as published literature had already evidenced the rapid decay of BLS skills in unselected lay rescuers,31, 32, 33, 34 but extrapolation to the unique scenario of HD would have been inappropriate, considering the strong motivation and the peculiar characteristics of the trained BLSD providers. Actually the latest guidelines have simplified cardiopulmonary resuscitation and it generates the hypothesis that BLS skills might be better retained with these recent modifications, but this speculation needs to be prospectively verified. Preliminary experiences of HD16 have shown the short-term retention of BLSD skills is unsatisfactory, but these pioneer findings were based on a small population and a very short follow-up. Our study confirmed these findings and expanded the knowledge on BLSD performance in home-defibrillation providers by adding an analysis of the BLSD components. In our study the least affected component of BLSD performance was AED use, which actually remained stable over time. This observation and previous findings in unselected lay rescuers raise the issue whether candidates for HD programs should be trained to formal BLSD or to AED use only. Some evidence suggests an improved outcome of OHCA with AED use only.36 However, theoretical consideration and published evidence suggest that complete BLSD maneuvers may offer better results, at least in patients with delayed shock delivery.37 The use of chest compressions only as a surrogate for formal BLS has been suggested as an alternative.38, 39, 40 However, reluctance to perform mouth-to-mouth ventilation on a stranger due to repulsion or fear of infection (commonly observed in public access defibrillation programs) is not expected to represent a problem in HD programs. In the absence of definitive recommendations, current guidelines and renewed emphasis on cardiopulmonary resuscitation in advanced cardiovascular life support suggest that both BLS and AED use should be included in training programs, although in some circumstances, AED use may reasonably precede BLS training.12 Whatever strategy is chosen, formal training, videotape/DVD, or dedicated Web site–based self-instruction represent possible options. However, formal training is explicitly required by the law at least in some countries in Europe.12 In addition, the observation in our study of occasional candidate BLSD providers repeatedly not able to observe the required safety measures at the time of AED discharge requires further investigation to clarify whether acquisition of BLSD skills should be verified before releasing an unconditioned authorization to operate in-home AEDs. Actually, the United States Food and Drug Administration specifies that AEDs should be used by “trained individuals,” but allows local authorities to determine specific training requirements.11, 41 The fast decay of BLSD skills in lay rescuers raises the issue of retraining strategies. Formal BLSD retraining and self-retraining represent possible options, but compliance to retraining session is expected to be low. Technical maintenance of AEDs may represent a critical issue of HD programs as well. A possible strategy to manage both BLSD retraining sessions and attendance to AEDs technical maintenance schedule comes from the second relevant finding of the present study: despite high motivation of enrolled families, compliance to follow-up contacts with retraining sessions and AED checks was highly influenced by its concomitant arrangement with clinical appointments. This finding generates the hypothesis that giving the patients the opportunity to check their home AED and attend retraining sessions on the occasion of clinical appointments (as occurs for pacemaker or ICD controls) might be a successful option.
The third relevant finding of our study is that in families who participate in an HD program, the program itself and the presence of an AED at home had no effect on anxiety, depression, and quality of life. Actually, a possible limitation of this observation is that our study investigated levels of anxiety, depression, and the quality of life only in families who agreed to join the program. This may represent a selection bias, but also likely resembles participation in home-defibrillation programs in clinical practice. Moreover, in the absence of a control group, we cannot exclude a lack of quality of life improvement as a result of adherence to our HD program. We did not observe any AED intervention in the study period. Actually, our study was not designed to investigate the effect of HD on prognosis of our population, but it might have affected the impact on anxiety and depression. In fact, the PAD trial described a “transient psychological trauma” in lay rescuers. The witnessed death of a loved one could be even more dramatic and the potential for serious psychological sequelae after unsuccessful resuscitation and AED use should be considered.13 The absence of any AED use during the study period is not surprising as a significant delay in the onset of survival benefit from implanted cardioverter defibrillators postinfarction has been clearly described in the MADIT II trial population42 and indicates that studies designed to assess the impact on prognosis and cost-effectiveness analyses of home-defibrillation programs require appropriate long-term follow-up. Indeed, a major limitation of home-defibrillation programs is that, unfortunately, most patients who have cardiac arrest at home cannot be identified on the basis of their clinical characteristics.2 This observation is the consequence of a high number of cardiac arrests in large populations at low or very low relative risk of sudden death as compared with a low absolute number of cardiac arrests in small populations at intermediate or high risk of sudden cardiac death.43 Therefore, selection of candidates is a critical issue in HD programs design, as it generates many implications in terms of human and economic resource allocation. Accordingly, cost-effectiveness of home-defibrillation programs is mainly a function of selection criteria and follow-up duration. Then, potential candidates for pilot clinical research on HD should probably be selected from a population of patients at intermediate risk of sudden death not eligible for ICD implantation on the basis of current evidence, including selected patients with cardiac channelopathies, ischemic heart disease, and systolic dysfunction, or previous cardiac arrest of reversible causes.
Current evidence does not support HD as a high priority in public health policies, but the potential interest of families of patients at intermediate risk for sudden death cannot be disregarded. The interest of patients to buy AEDs “out of the pocket” has been documented,21 and our study supports the creation of a regulatory policy that includes training.
The implications for clinical practice and research of our study are that the expansion of “home defibrillation” and verification of BLSD skills acquisition should be considered to ensure safe and effective AED operation; that retraining sessions and AED checks would be probably best arranged on the occasion of clinical appointments to maximize compliance; and that no negative impact of participation in an HD program is expected to arise over time in families who agree to join an HD program at least in the absence of AED interventions.
Conclusions
Epidemiologic and clinical observations support a possible role of HD programs to improve the outcome of OHCA, but evidence to support the allocation of public health care resources to these projects is still awaited. However, private-funded HD initiatives and future research should consider that overall BLSD performance of families of patients affected by ischemic heart disease decreases over time after training, although the ability to operate AEDs appears to be the least affected component. Retraining strategies and compliance to an AED maintenance schedule in HD programs represent a critical challenge. Compliance with retraining sessions and AED checks appears to be significantly increased if they are combined with clinical appointments. The implementation of an HD program does not appear to affect anxiety, depression, or the quality of life. The impact on prognosis of HD programs as well as their cost-effectiveness depend on the relative risk of the selected population and the time frame of the analysis and remain to be established.
We thank Tommaso Ianni and Tiziana De Santo for their precious assistance in study conduction and analysis of the data.
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The present study was supported by grants from the “Accademia dei Lincei, Lascito Cesare Tumedei,” Rome, Italy, and Medtronic Italia, Milan, Italy.
PII: S0002-8703(06)00655-7
doi:10.1016/j.ahj.2006.07.008
© 2006 Mosby, Inc. All rights reserved.
