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Sudden cardiac arrest: Studies on risk and outcome

Blom, M.T.

Publication date2014Document VersionFinal published version

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Citation for published version (APA):Blom, M. T. (2014). Sudden cardiac arrest: Studies on risk and outcome. Boxpress.

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CHAPTER 12

M.T. Blom*, S.G. Beesems*, P.C. Homma, J.A. Zijlstra, M. Hulleman, D.A. van Hoeijen, A. Bardai, J.G.P. Tijssen, H.L. Tan, R.W. Koster.

* These authors contributed equally

Accepted with revision in Circulation, 2014

206

out-of-hospital cardiac arrest (OHCA) was advocated in The Netherlands. We aimed to establish whether survival with favorable neurologic outcome after

We performed a population-based cohort study, including patients with OHCA from cardiac causes between 2006 and 2012, excluding EMS-witnessed arrests. We determined survival status at each stage (to emergency room, to admission, to discharge) and examined temporal trends using logistic regression analysis with ‘year-of-resuscitation’ as independent variable. By adding each co-variable subsequently to the regression model, we investigated their impact on the Odds Ratio (OR) of ’year-of-resuscitation’. Analyses were performed according to initial rhythm (shockable vs. non-shockable), and AED-use. Rates of survival with favorable neurologic outcome after OHCA increased

for trend

207

Chapter 12

Out-of-hospital cardiac arrest (OHCA) is a leading cause of death in industrialized countries, affecting 300 000 individuals/year in North America.1,2 In Europe 275 000 OHCAs are treated annually.3 Although the majority of OHCAs ( 70%) have a cardiac

4 OHCA is lethal in most cases.5,6 Interventions aiming at improved bystander cardiopulmonary resuscitation

to increase survival rates after OHCA. A recent study7 showed that national initiatives to increase bystander CPR have improved survival rates in Denmark. In the Netherlands,

8 We aimed to establish (1) whether survival with favorable neurologic outcome after OHCA in the community has increased in the Netherlands between 2006 and

changes in resuscitation care may explain altered survival rates.

The Amsterdam Resuscitation Study (ARREST) is an ongoing, prospective registry of all-cause OHCA in the North Holland province of The Netherlands. ARREST was set up to establish the determinants of outcome of OHCA,8,9 and gain insight in the genetic, clinical and pharmacological determinants of OHCA in the general population.10,11 The study region covers 2404 km2 (urban and rural communities) and has a population of 2.4 million people. The present investigation covered the study period January 1, 2006 - December 31, 2012. The Medical Ethics Review Board of the Academic Medical Center, Amsterdam, approved the study and gave a waiver for obtaining (written) informed consent.

In a medical emergency, people dial the national emergency number. When the Emergency Medical Service (EMS) dispatcher suspects OHCA, two ambulances are

Life Support. The placement of AEDs in public areas (‘onsite AED’) was stimulated but not centrally controlled or directed.8 Furthermore, the implementation of changed

208

CPR guidelines (from 15 compressions with two ventilations [Guidelines 2000] to 30 compressions with two ventilations [‘30:2 CPR-protocol’, Guidelines 2005] lasted well into 2007.12

After each CPR attempt, EMS paramedics routinely send the continuous ECG from

dedicated software (Code Stat Reviewer 9.0, Physio-Control, Redmond WA, USA). If an AED is used, ARREST personnel visit the AED site shortly after the OHCA, and

CPR-procedure (witness of OHCA, bystander CPR performed, AED-use) are collected according to Utstein recommendations,13 by means of a pre-coded set of questions that ambulance staff is required to answer, and by retrieving ambulance data of the event. Data on post-resuscitation care (therapeutic hypothermia [TH] or percutaneous coronary intervention [PCI]) were derived from hospital records. Survival was assessed at three time points: survival to transfer of care at ER (hereafter called survival to ER), survival to hospital admission, and survival to hospital discharge (information retrieved from hospital records and civic registry).

Arrests were deemed to result from cardiac causes unless an unequivocal non-cardiac cause was documented (e.g., trauma, drowning). We excluded EMS-witnessed cardiac arrests, aborted resuscitation efforts in individuals with a “do not resuscitate” status,

variable, and was determined by analyzing the impedance signal in the continuous ECG

Category (CPC) scale was assessed by reviewing hospital charts of patients who survived

2.13-15

To evaluate changes in baseline resuscitation characteristics, hospital care and survival rates by calendar year, we calculated a P-value for trend using Chi-square test (Linear-

209

Chapter 12

by-Linear) for dichotomous data. For continuous variables, we used linear regression

Jonckheere-Terpstra test. We evaluated changes in in-hospital care (TH and/or PCI

performed) in patients admitted to hospital. We assessed whether survival with favorable

neurologic outcome had improved over time using logistic regression analysis, with

the independent variable ‘year-of-resuscitation’ as a continuous variable. Survival with

rhythm (shockable or non-shockable). Survival per stage (to ER, to hospital admission

and to hospital discharge) was regressed by selecting patients who had survived to the

previous stage.

To establish which factor contributed to increased rates of survival with favorable

with ‘year-of-resuscitation’ as the independent variable. We then analyzed which

with favorable neurologic outcome. We then added such a variable to the model, to

determine whether the OR of ‘year-of-resuscitation’ would be adjusted towards the

1, indicating that the effect of ‘year-of-resuscitation’ is (at least partly) explained by

analysis.

Hospital-care variables were evaluated in patients admitted to hospital alive.

CPR-protocol was assessed for the years 2006 and 2007, since implementation of

protocol change occurred in that period.12 Only these years were used when we analyzed

the association between protocol and survival with favorable neurologic outcome.

data sets using multivariate imputation models using information from all pre-hospital

OHCA variables presented in Table 1. Since AED-use is strongly associated with other

or no AED-use) before running imputation models. Missing data on outcome were not

imputed. We then compared estimates from the observed data set with the estimates

from the imputed data sets.

Continuous variables were described as means and standard deviations (SD), or medians

and interquartile range where appropriate, and categorical variables as absolute numbers

analyzed using the statistical software package of SPSS (SPSS for Mac, version 20.0,

SPSS Inc.).

Supplemental Table s1). The incidence of EMS treated OHCA (with/without cardiac

210

cause) did not change during the study period. Patient and resuscitation characteristics

of dispatched police AEDs. There was a large increase over time in AED-use (2006: 21.4% to 2012: 59.3%, p

211

Chapter 12

2006

2007

2008

2009

2010

2011

2012

851

876

874

871

887

900

874

Mea

n ag

e, y

ears

, (SD

) 65

.0 (1

5.7)

65.1

(15.

9)65

.1 (1

5.6)

65.9

(15.

0)67

.6 (1

4.6)

66.3

(16.

0)67

.1 (1

4.1)

212

(n=593) either because patients were already conscious (n=369, 62.2%), or because only

palliative care was given (n=138, 23.3%). Only 86 (14.5%) patients did not receive

were not performed.

Table 2 shows rates of survival with favorable neurologic outcome per year. In the total

neurologic outcome occurred from 16.2% in 2006 to 19.7% in 2012 (OR 1.04, 95%

CI 1.01-1.07). This was largely due to improved rates among patients with shockable

of survival with favorable neurologic outcome was observed among patients with non-

shockable

further analyses in this patient group.

213

Chapter 12

2006

2007

2008

2009

2010

2011

2012

n(%)

138

(16.

2)13

5 (1

5.4)

183

(21.

0)15

0 (1

7.3)

166

(18.

8)17

2 (1

9.3)

168

(19.

7)0.

021

1.04

(1.0

1-1.

07)

41 (0

.7)

125

(29.

1)12

1 (2

9.3)

171

(41.

1)14

1 (3

6.5)

147

(37.

9)15

9 (3

7.9)

154

(41.

4)

214

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

2006 2007 2008 2009 2010 2011 2012

Per

cent

age

Year

No AED-use

Dispatched AED

Local AED

Among patients with shockable rhythm, survival rates increased at each

95% CI 1.06-1.16). Among patients who reached ER alive, the proportion of those

1.11), as did the proportion of patients discharged alive after admission to hospital

neurologically intact at hospital discharge remained high throughout the study period

To explore which changes might explain the increase in survival with favorable neurologic outcome in patients with a shockable rhythm, we analyzed which variables changed the crude OR of ‘year-of-resuscitation’ towards 1 when added to the logistic regression model. Variables not included in the analyses were ‘Male sex’ and ‘PCI-treatment’ (no change), and ’30:2 CPR-protocol’ (no association16) (Supplemental Table s2). Table 3 shows the (adjusted) ORs of ‘year-of-resuscitation’ with each consecutively added variable. Only two variables decreased the OR of ‘year-of-resuscitation’ to a non-

what might explain the observed increased rates of survival with favorable neurologic

215

Chapter 12

1.08

(1.0

4-1.

13)

216

this group, AED-use statistically explained the improved survival rates. Adding other variables to the model did not show relevant changes. In the patient group without

‘year-of-resuscitation’. Repeating the analysis with imputation for missing data showed comparable results (Supplemental Tables s3 and s4).

We report an increase in rates of survival with favorable neurologic outcome after OHCA (16.2% to 19.7%) in The Netherlands during a 7-year study period, though solely in patients presenting with a shockable rhythm (29.1% to 41.4%). Survival increased at each stage of the resuscitation process, but the strongest trend was found in the pre-hospital phase (OR 1.11). The proportion of patients that were neurologically intact remained high throughout the study period (89.9% to 95.1%). Rates of AED-use almost tripled during the study period (21.4% to 59.3%), thereby decreasing the time

rate for a considerable part.

When compared with other countries, Dutch pre-hospital resuscitation care had already high standards at the beginning of our study period.17-19 For instance, the increased bystander CPR rate to 44.9% in 2010 in Denmark as reported by Wissenberg et al.7 is still low compared to the 65.8% of resuscitations with bystander CPR at the start of our study period in 2006. Similarly, the Danish increase in 30-day survival (to 10.8% in 2010) is much lower than the rate of survival with favorable neurologic outcome in 2006 (16.2%) in the present study. Nonetheless, even in The Netherlands, there was ample room for improvement. The survival analysis at each consecutive stage of resuscitation care showed that the largest increase was found in the pre-hospital phase, indicating that the large investments in improvement of pre-hospital care had the desired effects. The subsequent increased survival rate after hospital admission clearly shows that improving pre-hospital survival rates after OHCA is not ‘merely changing the place to die’, as some skeptics of

et al.20 we also show that survival with favorable neurologic outcome among patients

217

Chapter 12

who were admitted to hospital alive was still strongly associated with pre-hospital factors (Supplemental Table s5). Nonetheless, in the patient group in which no AED was used we still observed an increase in survival that was not explained by the studied pre-

Previous studies21,22

with the implementation of police AED programs. In our study region, apart from the

AED and trained in basic life support, thereby steadily increasing the number of available dispatched AEDs. Furthermore, the Netherlands Heart Foundation has launched the ‘six-minutes zone’ campaign in 2007, aiming to raise AED-awareness in the community

The proportion of resuscitations with connection times

218

after OHCA between 2006 and 2012 in The Netherlands in patients presenting with a shockable rhythm. Survival increased at each stage of the resuscitation process, but the strongest trend was observed in the pre-hospital phase. AED-use rates almost

connection. Increased AED-use is associated with increased survival in patients with a shockable initial rhythm. We recommend continuous efforts to improve resuscitation care, with strong emphasis on introducing or extending AED programs, involving both dispatched AEDs and onsite AEDs.

We are greatly indebted to all participating EMS dispatch centers (Amsterdam, Haarlem and

Alkmaar), regional ambulance services (Ambulance Amsterdam, GGD Kennemerland, Witte Kruis and

Schiphol airport and Meditaxi, for their cooperation and support. We greatly appreciate the contributions

of Loes Bekkers, Jocelyn Berdowski, Jeanet Glas, Roos Konings, Esther Landman, Renate van der Meer,

Anne Spanjaart and Remy Stieglis to the data collection, data entry, and patient follow-up. We thank all

the students of the University of Amsterdam who helped collect the AED data.

918.86.616), the Dutch Medicines Evaluation Board (MEB/CBG) the European Community’s Seventh

Framework Programme (FP7, grant 241679, ARITMO), and Biobanking and Biomolecular Research

Infrastructure The Netherlands (BBMRI-NL)

RWK received funding for the ARREST data collection by unconditional grants from Physio-Control

USA), Cardiac Science (Waukesha, WI, USA), ZonMW (#82711001) and the Dutch Heart Foundation

(#2010T083). The funders had no access to the data and did not contribute to the preparation of this

manuscript. Disclosures: none.

219

Chapter 12

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Stroke Statistics Subcommittee. Heart disease and stroke statistics-2011 update: a report from the

3. Atwood C, Eisenberg MS, Herlitz J, Rea TD. Incidence of EMS-treated out-of- hospital cardiac arrest

4. Myerburg, R.J. Sudden cardiac death: exploring the limits of our knowledge. J. Cardiovasc. Electrophysiol. 12, 369–381 (2001).

5. Iwami T, Nichol G, Hiraide A, et al. Continuous improvements in “chain of survival” increased survival after out-of-hospital cardiac arrests: a large-scale population-based study. Circulation.

6. Aufderheide TP, Yannopoulos D, Lick CJ, Myers B, Romig LA, Stothert JC, Barnard J, Vartanian L, Pilgrim AJ, Benditt DG. Implementing the 2005 American Heart Association Guidelines improves

7. Wissenberg M, Lippert FK, Folke F, et al. Association of national initiatives to improve cardiac arrest management with rates of bystander intervention and patient survival after out-of-hospital cardiac

8. Berdowski J, Blom MT, Bardai A, Tan HL, Tijssen JG, Koster RW. Impact of onsite or dispatched

9. Bardai A, Berdowski J, van der Werf C, et al. Incidence, causes, and outcomes of out-of-hospital cardiac arrest in children. A comprehensive, prospective, population-based study in the Netherlands. J

locus at 2q24.2 through genome-wide association in European ancestry individuals. PLoS Genet.

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professionals from a task force of the International Liaison Committee on Resuscitation (American Heart Association, European Resuscitation Council, Australian Resuscitation Council, New Zealand Resuscitation Council, Heart and Stroke Foundation of Canada, Inter- American Heart Foundation,

14. Herlitz J, Ekstrom L, Wennerblom B, Axelsson A, Bång A, Holmberg S. Prognosis among survivors

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15. Brain Resuscitation Clinical Trial I Study Group. A randomized clinical study of cardiopulmonary-

16. Berdowski J, ten Haaf M, Tijssen JG, Chapman FW, Koster RW. Time in recurrent ventricular

1431.

18. Sasson C, Rogers MA, Dahl J, Kellermann AL. Predictors of survival from out-of-hospital cardiac

19. Berdowski J, Berg RA, Tijssen JG, Koster RW. Global incidences of out-of-hospital cardiac arrest and

20. Hollenberg J, Lindqvist J, Ringh M, et al. An evaluation of post-resuscitation care as a possible

252.

22. Husain S, Eisenberg M. Police AED programs: a systematic review and meta-analysis. Resuscitation.

23. Vadeboncoeur T, Stolz U, Panchal A, et al. Chest compression depth and survival in out-of-hospital

221

Chapter 12

2006

2007

2008

2009

2010

2011

2012

2,36

4 76

82,

371

123

2,38

4 01

52,

402

969

2,42

5 50

82,

446

997

2,46

3 78

0

1594

1827

1571

1878

1750

1889

2002

1251

1

resi

dent

s67

7766

7872

7781

1090

1102

1114

1162

1166

1181

1102

7917

4646

4748

4848

45

Incl

udin

g am

bula

nce

witn

esse

d92

293

895

795

897

899

094

366

86

851

876

874

871

887

900

874

6133

ambu

lanc

e w

itnes

sed

/ 10

0,00

0 re

side

nts

3637

3736

3737

36

222

Age, decades 0.75 (0.71-0.79)

223

Chapter 12

AED

-use

No

AED

-use

1.08

(1.0

4-1.

13)

224

Age, decades 0.64 (0.59-0.70)