Michiel Hulleman

Improved Survival After Out-of-Hospital Cardiac Arrest and Use of Automated External Defibrillators

Background— In recent years, a wider use of automated external defibrillators (AEDs) to treat out-of-hospital cardiac arrest was advocated in The Netherlands. We aimed to establish whether survival with favorable neurologic outcome after out-of-hospital cardiac arrest has significantly increased, and, if so, whether this is attributable to AED use. Methods and Results— We performed a population-based cohort study, including patients with out-of-hospital cardiac arrest from cardiac causes between 2006 and 2012, excluding emergency medical service–witnessed arrests. We determined survival status at each stage (to emergency department, to admission, and to discharge) and examined temporal trends using logistic regression analysis with year of resuscitation as an independent variable. By adding each covariable subsequently to the regression model, we investigated their impact on the odds ratio of year of resuscitation. Analyses were performed according to initial rhythm (shockable versus nonshockable) and AED use. Rates of survival with favorable neurologic outcome after out-of-hospital cardiac arrest increased significantly (N=6133, 16.2% to 19.7%; P for trend=0.021), although solely in patients presenting with a shockable initial rhythm (N=2823; 29.1% to 41.4%; P for trend<0.001). In this group, survival increased at each stage but was strongest in the prehospital phase (odds ratio, 1.11 [95% CI, 1.06–1.16]). Rates of AED use almost tripled during the study period (21.4% to 59.3%; P for trend <0.001), thereby decreasing time from emergency call to defibrillation-device connection (median, 9.9 to 8.0 minutes; P<0.001). AED use statistically explained increased survival with favorable neurologic outcome by decreasing the odds ratio of year of resuscitation to a nonsignificant 1.04. Conclusions— Increased AED use is associated with increased survival in patients with a shockable initial rhythm. We recommend continuous efforts to introduce or extend AED programs.

Implantable Cardioverter-Defibrillators Have Reduced the Incidence of Resuscitation for Out-of-Hospital Cardiac Arrest Caused by Lethal Arrhythmias

Background— Over the last decades, a gradual decrease in ventricular fibrillation (VF) as initial recorded rhythm during resuscitation for out-of-hospital cardiac arrest (OHCA) has been noted. We sought to establish the contribution of implantable cardioverter-defibrillator (ICD) therapy to this decline. Methods and Results— Using a prospective database of all OHCA resuscitation in the province North Holland in the Netherlands (Amsterdam Resuscitation Studies [ARREST]), we collected data on all patients in whom resuscitation for OHCA was attempted in 2005–2008. VF OHCA incidence (per 100 000 inhabitants per year) was compared with VF OHCA incidence data during 1995–1997, collected in a similar way. We also collected ICD interrogations of all ICD patients from North Holland and identified all appropriate ICD shocks in 2005–2008; we calculated the number of prevented VF OHCA episodes, considering that only part of the appropriate shocks would result in avoided resuscitation. VF OHCA incidence decreased from 21.1/100 000 in 1995–1997 to 17.4/100 000 in 2005–2008 (P<0.001). Non-VF OHCA increased from 12.2/100 000 to 19.4/100 000 (P<0.001). VF as presenting rhythm declined from 63% to 47%. In 2005–2008, 1972 ICD patients received 977 shocks. Of these shocks, 339 were caused by a life-threatening arrhythmia. We estimate that these 339 shocks have prevented 81 (minimum, 39; maximum, 152) cases of VF OHCA, corresponding with 33% (minimum, 16%; maximum, 63%) of the observed decline in VF OHCA incidence. Conclusions— The incidence of VF OHCA decreased over the last 10 years in North Holland. ICD therapy explained a decrease of 1.2/100 000 inhabitants per year, corresponding with 33% of the observed decline in VF OHCA.

Comorbidity and favorable neurologic outcome after out-of-hospital cardiac arrest in patients of 70 years and older.

INTRODUCTION Advanced age is reported to be associated with lower survival after out-of-hospital cardiac arrest (OHCA). We aimed to establish survival rate and neurological outcome at hospital discharge after OHCA in older patients and evaluated whether pre-OHCA comorbidity was associated with favorable neurologic outcome. METHODS From a prospective registry of all cardiopulmonary resuscitation (CPR) attempts after OHCA, we established survival in 1332 patients aged ≥ 70 years in whom resuscitation with non-traumatic etiology was attempted in 2009-2011. Pre-OHCA factors (age, gender, residing in long-term care institution, Charlson Comorbidity Index [CCI] score) and resuscitation parameters (initial rhythm, bystander witnessed, bystander CPR and time to defibrillator connection) with survival at hospital discharge with favorable neurologic outcome were regressed in the 851 patients of whom CCI was known. RESULTS We found a 12% survival to discharge rate in patients aged ≥ 70 years (70-79 years: 16%; ≥ 80 years: 8%, p=0.001). Among surviving patients, 90% survived with favorable neurologic outcome. In a model with only pre-OHCA factors age was significantly associated with outcome (age OR 0.94, 95%CI 0.91-0.98), p = 0.003). High CCI score (≥ 4) was not statistically significant when associated with survival (7% vs. 12%, OR 0.53, 95%CI (0.25-1.13), p = 0.10). When adjusted for resuscitation parameters, OR for high CCI was 0.71 (95% CI 0.28-1.80, p = 0.47), also none of the other pre-OHCA factors remained statistically significant. CONCLUSION In the Netherlands, the survival rate in older patients was 12%; the great majority survived with favorable neurologic outcome. Resuscitation-related factors and not comorbidity determine outcome after OHCA in older patients.

Causes for the declining proportion of ventricular fibrillation in out-of-hospital cardiac arrest

AIMS The reported proportion of ventricular fibrillation (VF) in out-of-hospital cardiac arrest (OHCA) has declined worldwide. VF decline may be caused by less VF at collapse and/or faster dissolution of VF into asystole. We aimed to determine the causes of VF decline by comparing VF proportions in relation to delay from emergency medical services (EMS) call to initial ECG (call-to-ECG delay), and VF dissolution rates between two study periods. METHODS Data from the AmsteRdam REsuscitation STudies (ARREST), an ongoing OHCA registry in the Netherlands, were used. We studied cardiac OHCA in the study periods 1995-1997 (n=917) and 2006-2012 (n=5695). Cases with available ECG and information on call-to-ECG delay were included. We tested whether initial VF proportion and VF dissolution rates differed between both study periods using logistic regression. RESULTS Despite a 15% VF decline between the periods, VF proportion around EMS call remained high in 2006-2012 (64%). The odds ratio (OR) for VF proportion in 2006-2012 vs. 1995-1997 was 0.52 (95%-CI 0.45-0.60, P<0.001), with similar rates of VF dissolution in both periods (P=0.83). VF decline was higher for unwitnessed collapse (OR 0.41, 95%-CI 0.28-0.58) and collapse at home (OR 0.50, 95%-CI 0.42-0.59), but not for categories of bystander CPR, age or sex. CONCLUSION VF proportion early after collapse remains high. VF decline is explained by the occurrence of less initial VF, rather than faster dissolving VF. An increase in unwitnessed OHCA and collapse at home contributes to the observed VF decline.

Predictive value of amplitude spectrum area of ventricular fibrillation waveform in patients with acute or previous myocardial infarction in out-of-hospital cardiac arrest

BACKGROUND Amplitude spectrum area (AMSA) of ventricular fibrillation (VF) has been associated with survival from out-of-hospital cardiac arrest (OHCA). Ischemic heart disease has been shown to change AMSA. We studied whether the association between AMSA and survival changes with acute ST-elevation myocardial infarction (STEMI) as cause of the OHCA and/or previous MI. METHODS Multivariate logistic regression with log-transformed AMSA of first artifact-free VF segment was used to assess the association between AMSA and survival, according to presence of STEMI or previous MI, adjusting for resuscitation characteristics, medication use and comorbidities. RESULTS Of 716 VF-patients included from an OHCA-registry in the Netherlands, 328 (46%) had STEMI as cause of OHCA. Previous MI was present in 186 (26%) patients. Survival was 66%; neither previous MI (P=0.11) nor STEMI (P=0.78) altered survival. AMSA was a predictor of survival (ORadj: 1.52, 95%-CI: 1.28-1.82). STEMI was associated with lower AMSA (8.4mV-Hz [3.7-16.5] vs. 12.3mV-Hz [5.6-23.0]; P<0.001), but previous MI was not (9.5mV-Hz [3.9-18.0] vs 10.6mV-Hz [4.6-19.3]; P=0.27). When predicting survival, there was no interaction between previous MI and AMSA (P=0.14). STEMI and AMSA had a significant interaction (P=0.002), whereby AMSA was no longer a predictor of survival (ORadj: 1.03, 95%-CI: 0.77-1.37) in STEMI-patients. In patients without STEMI, higher AMSA was associated with higher survival rates (ORadj: 1.80, 95%-CI: 1.39-2.35). CONCLUSIONS The prognostic value of AMSA is altered by the presence of STEMI: while AMSA has strong predictive value in patients without STEMI, AMSA is not a predictor of survival in STEMI-patients.

Minimizing pre- and post-shock pauses during the use of an automatic external defibrillator by two different voice prompt protocols. A randomized controlled trial of a bundle of measures

BACKGROUND Previous large retrospective analyses have found an association between duration of peri-shock pauses in cardiopulmonary resuscitation (CPR) and survival. In a randomized trial, we tested whether shortening these pauses improves survival after out-of-hospital cardiac arrest (OHCA). METHODS Patients with OHCA between May 2006 and January 2014 with shockable initial rhythm, treated by first responders, were randomized to two automated external defibrillator (AED) treatment protocols. In the control protocol AEDs performed post-shock analysis and prompted rescuers to a pulse check (Guidelines 2000). In the experimental protocol a 15s period of CPR during and after charging of the AED was added to the voice prompts and CPR was resumed immediately after defibrillation (modification of the Guidelines 2005). Survival was assessed at hospital admission and discharge. RESULTS Of 1174 OHCA patients, 456 met the inclusion criteria: 227 were randomly assigned to the experimental protocol and 229 to the control protocol. The experimental group experienced shorter pre-shock pauses (6 [5-11]s vs. 20 [18-23]s; P<0.001), and shorter post-shock pauses (7 [6-9]s vs. 27 [16-34]s; P<0.001). Similar proportions of patients survived to hospital admission (experimental: 62% vs. CONTROL 65%; RR [95%CI] 0.96 [0.83-1.10], P=0.51), and hospital discharge (experimental: 42% vs. CONTROL 38%; RR [95%CI] 1.09 [0.87-1.37], P=0.46). CONCLUSION In patients with OHCA and shockable initial rhythms, treatment with AEDs with the experimental protocol shortened pre-shock and post-shock CPR pauses, and increased overall CPR time, but did not improve survival to hospital admission or discharge. CLINICAL TRIAL REGISTRATION http://www.isrctn.com unique identifier: ISRCTN72257677.

Conduction disorders in bradyasystolic out-of-hospital cardiac arrest

AIMS Bradyasystolic heart rhythms are often recorded in out-of-hospital cardiac arrest (OHCA). Atrioventricular (AV) conduction disorders might lead to OHCA, but the prevalence of AV-conduction disorders and other bradyasystolic rhythms in OHCA is unknown. These patients might benefit from pre-hospital pacing. We aimed to determine the prevalence of different types of bradyasystolic heart rhythms in OHCA, including third degree AV-block, and document survival rates. METHODS We used data from the ARREST-registry of OHCA in the Netherlands. Patients with bradyasystolic OHCA in 2006-2012 were included. ECGs were classified according to the presence of P-waves and QRS complexes in five rhythm groups. Differences in survival to discharge in relation to resuscitation characteristics, rhythm and pacing were tested using Chi-Square test and multivariate regression analysis. RESULTS We included 2333 patients with a bradyasystolic rhythm; 371 patients (16%) presented with a third degree AV-block. In total 45 patients (1.9%, 95%-CI 1.4-2.5%) survived. A third degree AV-block (adjusted OR 0.86, 95%-CI 0.38-1.96) or pacing (adjusted OR 0.89, 95%-CI 0.21-3.78) was not associated with survival. Pacing was initiated in 110 patients (4.7%), after a long delay (median 18.7min). The strongest association with survival was found for the presence of a bradycardia (vs. asystole) (adjusted OR 4.20, 95%-CI 1.79-9.83), bystander witnessed (OR 4.13, 95%-CI 1.45-11.8) and EMS witnessed collapse (OR 5.18, 95%-CI 2.77-9.67). CONCLUSION In bradyasystolic OHCA, 16% of all patients present with third degree AV-block, but survival for these and other bradyasystolic patients remains poor. Pacing is seldom initiated, often delayed, and rarely beneficial.

Atrial fibrillation mimicking ventricular fibrillation confuses an automated external defibrillator

A 47-year-old man suffered an out-of-hospital cardiac arrest. For scientific purposes, we analysed the electrocardiogram of the deployed automated external defibrillator (AED) [1]. Initially, the AED detected a non-shockable rhythm, caused by atrial fibrillation (AF) with high-degree atrioventricular block and slow ventricular escape rhythm (Fig. 1 panel A). During continued rhythm analysis, however, no escape beats occurred and a shock was delivered because isolated AF waves were erroneously interpreted as ventricular fibrillation (VF) (Fig. 1 panels B–C). In-hospital AF mimicking VF in monitored patients has been described before [2, 3], but ours is the first report of inappropriate AED therapy for AF mimicking VF during out-of-hospital cardiac arrest. The sensitivity and specificity of AED algorithms is related to the defibrillation threshold as defined in the AED algorithm [4]. The defibrillation threshold in the AED in this case report was 0.08mV, which is lower than other AEDs where it ranges from 0.1 to 0.2mV. An amplitude below the threshold is considered asystole. In this case the AF waves were between 0.08 and 0.2mV, interpreted as ‘fine’ VF. It is important to recognise that in current clinical practice we do not routinely retrieve and analyse AED electrocardiograms, and AED shocks are generally used as a proxy for VF. This practice may result in treatment errors. Clearly, AED electrocardiograms should always be analysed to allow for correct clinical decision-making.

Resuscitation for out-of-hospital cardiac arrest in adults with congenital heart disease

AIMS Adult congenital heart disease (ACHD) patients are at increased risk of sudden cardiac death and out-of-hospital cardiac arrest (OHCA). Currently, insufficient data exist on outcome, causes and circumstances of OHCA of ACHD patients resuscitated for OHCA. We investigate these parameters in ACHD patients in comparison to OHCA in the general population. METHODS AND RESULTS We identified ACHD patients with OHCA by linking data from a Dutch nationwide registry of ACHD patients (CONCOR, n = 15,727), and ARREST, a cohort of OHCA cases (n = 17,868). 62 ACHD patients with OHCA were identified. Ventricular septal defect (n = 11), bicuspid aortic valve (n = 10) and atrial septal defect (n = 8) were the most common diagnoses. We included OHCA cases from the general population as controls. ACHD patients were younger than controls (n = 11,624) at the time of OHCA (47 (SD ± 17) years vs. 66 (SD ± 15) years, respectively, p < 0.001), and more often had a shockable initial rhythm (67% vs 40%, respectively, p < 0.001). A cardiac cause of OHCA was identified in 76% of ACHD patients, with only 7% due to myocardial infarction or ischemia. Survival was better in ACHD patients than in controls (44% vs. 19%, p < 0.001), but this difference disappeared after correction for age, gender, witnessed arrest, bystander resuscitation, public location and shockable rhythm. CONCLUSIONS OHCA in ACHD patients occurs at young age, is rarely caused by ischemia and occurs mainly in patients with simple congenital defects. Risk stratification efforts should therefore not be restricted to ACHD patients with severe congenital defects.