Cardiovascular diseases are the main cause of death in Spain.1 Among them, there are high rates of ischemic heart disease with sudden cardiac death (SCD) as the most common form of death.2,3 Overall estimates of the incidence of cardiopulmonary arrest (CPA) in general and of SCD in particular vary widely in every country,4 mainly because the estimates are based on calculations that use different information sources, which can entail a certain margin of error.5 Similar to incidence, survival after out-of-hospital CPA varies considerably between countries with similar health care structures.6,7 Consequently, it is not uncommon to express CPA incidence and outcomes in relation to out-of-hospital emergency service care.8

Around 8 out of every 10 sudden cardiac arrests are known to be of cardiac etiology (or more generally, cardiovascular) and could be labeled as SCD.9,10 Hence, out-of-hospital CPAs are traditionally always attributed to a cardiac etiology unless a specific cause is clearly identified.11

Although some general results on out-of-hospital CPA in Spain have been published in recent years,12–14 there is no known figure on the true incidence of SCD in Spain. Information is also lacking on the final outcomes of patients who had an out-of-hospital CPA of possible cardiovascular cause.

The aim of this study was to describe the incidence and characteristics of out-of-hospital SCD seen by emergency teams (ETs) and the outcomes at hospital discharge in terms of survival and neurologic outcome.

A retrospective analysis was conducted of a continuous registry of patients attended by out-of-hospital ETs for CPA between January 2008 and December 2012. The characteristics and methodology of the registry have been described previously.13 Briefly, the Registro Andaluz de Parada Cardiaca Extrahospitalaria (Andalusian Registry of Out-of-hospital Cardiac Arrest) is a prospective, ongoing registry of CPA cases seen by ETs of the Empresa Pública de Emergencias Sanitarias de Andalucía (EPES, Public Health Emergency Company of Andalusia). This public health service handles out-of-hospital health emergencies in Andalusia, with an actual catchment population of 5575128 inhabitants (67.14% of the population, as the total for Andalusia is 8 302 923). Its ETs have an on-board physician.

During the period analyzed, 15 517 patients were attended in a situation of CPA and/or death. In 65.3% of these patients, the ETs only recorded patient death (by diagnosing instantaneous death or unattended death, ICD-9 codes 798.1 and 798.9, respectively). Advanced life support measures were begun in 34.6% of all patients but were stopped in 323 (2.1%) patients because the measures were considered futile. Among 5067 patients who finally received advanced life support, arrest was considered to be of cardiac etiology in 4072 (80.4%) (Figure).

Figure.

Flow chart for patients included in the analysis (January 2008-December 2012). CPA, cardiopulmonary arrest.

(0.27MB).

The age range was 0 to 96 years: 199 patients (4.9%) were<35 years old, 14 of them in the first year of life; 2884 (70.8%) were between 35 and 74 years old, and 989 (24.3%) ≥ 75 years old.

Based on the catchment population with EPES land-based ETs, the incidence recorded was 14.6 SCD events per 100 000 inhabitants and year (10.6% men and 4.0% women): 8.0 and 2.7 cases per 100 000 inhabitants and year of men and women between 35 and 74 years, respectively.

Men accounted for 72.6% of these patients, 25% of arrests were treated with initial defibrillable rhythm, and 32.5% of patients arrived at the hospital, although 3.7% arrived while resuscitation measures were still underway, ie, without spontaneous pulse at hospital arrival. In this group, only 1 patient was discharged from the hospital. Among patients with an initial defibrillable rhythm, up to 58.3% arrived at the hospital with a pulse. Among all patients who arrived at the hospital with a pulse, 266 patients (20.1%) required no orotracheal intubation.

In the phase prior to ET arrival, excluding arrests witnessed by health professionals, basic life support measures were performed by witnesses in 20.9% of patients. Automatic defibrillators were used in 75 patients, on 5 occasions by lay witnesses.

Final survival at discharge for the entire series was 11.2% and 10.2% of patients had good neurologic outcome (CPC 1-2). Among these patients with good neurological outcome at discharge, 43.1% were not intubated during prehospital care. The general patient and care characteristics are shown in Table 1.

The variables associated with the probability of patients arriving alive at the hospital or arrival with a pulse are listed in Table 2. During hospitalization, 20 patients were treated with hypothermia and 249 patients underwent PCI.

Good neurologic outcome at hospital discharge in the group of admitted patients was associated with an action interval<8 min, initial defibrillable rhythm, witnessed CPA (particularly witnessed by the ET), and interventions prior to ET arrival, life support, and defibrillation (Table 3).

The logistic regression results for variables associated with patients arriving with a pulse at the hospital and hospital discharge with good neurologic outcome (CPC 1-2) (Tables 4 and 5, respectively) yielded the following variables of interest: defibrillable rhythm, witnessed CPA, CPA not occurring at home, and hospital treatment with PCI.

We present the results of the largest SCD series analyzed in Spain. The incidence observed in our registry, 14.6 cases per 100 000 inhabitants and year, is well below the figures reported by population registries in Spain,2 particularly when focusing on the age bracket with the highest prevalence of ischemic heart disease (35-74 years). In this age bracket, the population registries report figures of 21 and 5.6 cases, which are somewhat higher than 2-fold our results (8.0 men and 2.7 women per 100 000 inhabitants and year), particularly among men.3 These figures are noteworthy but are not unusual whenever registries of resuscitated arrests are compared with population data on sudden death, as the latter include all patients, even those not receiving health care. This is also a low annual incidence when compared with data from other countries that, although varying widely, have a mean of 35 and 54 cases per 100 000 inhabitants and year in Europe and North America, respectively.6–8 We estimated that 8 out of every 10 CPAs included in our registry were of cardiac cause, a common finding in the main registries similar to ours. This finding is of interest, particularly after the new etiologic classification of the latest recommendations on Utstein-style CPA data collection and reporting, which combines medical causes as a whole.16 This will also make it possible to compare future outcomes and to determine whether they can be carried over to our setting.

In our study, the approximate ratio of men-to-women is 3:1, and SCD affects a rather young population for the mean life expectancy of Spain. In this series, 1 out of every 4 arrests were seen after a telephone call motivated mainly for a reason other than altered consciousness. This should be taken into consideration by the coordination center for out-of-hospital emergency services because some of these situations, such as gasping, are known to be associated with a better prognosis.17

Survival with good neurologic outcome at discharge was 10.2%. A situation of ongoing resuscitation was not advantageous for patients because final survival focused on the group of patients admitted with a spontaneous pulse (almost 30% of all patients). Although noncardiac arrest has a poorer prognosis,18,19 the outcomes are similar to and even better than those reported by other large registries. In addition, global data indicate that survival is 6% in North America, 2% in Asia, 11% in Australia, and 9% in Europe.7 On comparing more recent data with years that coincide with the study period, we found survival rates ranging from 7.8% in Japan,20 9.0% in the United States,21 and 10.4% in Denmark.22

Despite these results, some aspects are very relevant and known to influence the final prognosis, thus warranting reflection.

A fourth of all CPAs were not witnessed, which made it hard to determine the time of the event and to draw conclusions on actual time intervals. Nevertheless, these intervals were longer than desirable both when the time of collapse could be estimated and when the call-to-ET arrival time was analyzed, although they were consistent with the findings published by other out-of-hospital emergency services in Spain.23,24 This is important because care begun within 8 minutes was associated with the probability of hospital admission. The phase prior to ET arrival reveals a critical area for improvement. Only 1 out of every 5 patients received basic life support from witnesses. Automatic defibrillators were also rarely used, a key aspect in our series, as 25% of patients had initial defibrillable rhythms and almost 60% of them arrived at the hospital alive. Despite these figures, both actions were associated with the final prognosis and the probability of patients being admitted alive to the hospital, respectively. It is essential to develop interventions that encourage public involvement in this preliminary phase. These are probably the most important actions to improve overall patient survival.22

More than half the arrests occurred at home, a factor negatively associated with the final prognosis. Arrest at home led to a lower prevalence of initial defibrillable rhythms and had a higher percentage of unwitnessed arrests, in which delays in ET intervention and lower rates of resuscitation by witnesses are a consistent finding in different countries with distinct out-of-hospital emergency service structures.25–27 Patient age and sex are also known prognostic factors,28,29 although in our series sex and age were associated with the probability of live hospital admission, but not with survival or neurologic outcome at discharge.

Along with initial rhythm, witnessing of the arrest by the ET was associated with survival with good neurologic outcome, a finding also reported in the literature.30

The proportion of specific types of care after resuscitation (hypothermia and PCI) was discrete. Because the percentages of application were low, it was to be expected that their statistical influence was not significant, as in the case of hypothermia. However, PCI correlated closely to survival and good final neurologic outcome. Although this is somewhat known,31 its impact on final outcome is nevertheless surprising. Because the role of hypothermia in post-resuscitation treatments is currently controversial,32 this finding is particularly noteworthy. Although possible selection biases of patients who received PCI cannot be excluded, it is an affordable strategy for facilities with primary angioplasty programs. The identification of ST-segment elevation acute myocardial infarction as the cause of the arrest and patient referral to a specific facility if the condition is identified should be part of the care provided by the ET after resuscitation. This debate on the regionalization of health care when attending CPAs is already underway.33

Sudden cardiac death usually occurs at home and affects a relatively young population. Although the rates of survival with good neurologic outcome are comparable to those of similar countries, there are major areas for improvement, particularly in the stage prior to ET arrival. Coronary interventional procedures had a considerable impact on patient recovery.

The registry is funded by a research grant from the Instituto Carlos III, with cofunding from the FEDER (Fondo Europeo de Desarrollo Regional) funds and the Fundación Progreso y Salud (public research agency of the Consejería de Salud of the Junta de Andalucía).

None declared.