The study consisted of a prospective register from 1 January 2010 to 31 January 2012 and included all patients who survived an OHCA and were admitted to CICUs at 5 teaching hospitals in Catalonia (Hospital Universitario de Bellvitge, Hospital Universitario Vall d’Hebron, Hospital Universitario Germans Trias i Pujol, Hospital Universitario de la Santa Creu i Sant Pau, and Hospital Universitario Josep Trueta). Patients with an unidentified cardiologic cause or incomplete information on the cardiac arrest were excluded. All cardiac arrest-related data (location of arrest, first recorded rhythm, resuscitation times and personnel, use of AED and/or nonautomated defibrillator, and neurologic assessment by Glasgow scale) were collected from the emergency medical services. Shockable rhythm was considered to exist when evidenced by electrocardiography or by defibrillation in the case of AED use. Likewise, both family and witnesses were asked about the circumstances of the cardiac arrest and the times elapsed.

During the patient's hospital stay, the following were recorded: cardiologic history, first electrocardiogram and pH, vital signs, percentage of orotracheal intubation/tracheotomy, additional test results, days of intubation and hospital stay, neurologic status, and mortality. Urgent coronary reperfusion times and procedures and affected territories were collected for patients with acute coronary syndrome with persistent ST segment elevation, and the culprit artery of the event for patients who underwent coronary angiography.

Treatment was at the discretion of the attending physician, with the ILCOR (International Liaison Committee on Resuscitation) consensus document available at all sites.14 Therapeutic hypothermia was used in all patients who were comatose after cardiac arrest secondary to ventricular fibrillation or recorded rhythm and who met none of the exclusion criteria (nonhypoxic coma, pregnancy, refractory hypotension or hypoxemia, life expectancy <6 months, or uncontrollable active bleeding). The technique was applied according to availability at the hospital and at the discretion of the attending physician. In-hospital mortality was recorded.

Neurologic status at discharge was assessed using the Glasgow-Pittsburgh categories14: cerebral performance category (CPC) 1 (no sequelae), CPC 2 (mild disability, independent, no institutionalization required), CPC 3 (severe disability, dependent, institutionalization required), CPC 4 (persistent vegetative state), and CPC 5 (death). As in previous studies,15 the first 2 were considered good neurologic outcomes and the last 3, poor neurologic outcomes or death.

Follow-up was performed at 6 months via a medical visit or phone interview. Vital status and neurologic status were determined by the Glasgow-Pittsburgh scale.

All data were entered cooperatively and synchronously using a web-based platform (Zoho Creator®, Zoho Corporation Pvt, Ltd). Informed consent for data use was obtained, and data confidentiality was guaranteed in compliance with the Spanish Law on Data Protection.

The results are expressed as the mean (standard deviation) for continuous variables with a normal distribution, medians for continuous variables with a non-Gaussian distribution, and percentages for categorical variables. The characteristics of patients with good and poor prognoses were compared using the χ2 test or Fisher exact test for categorical variables. Quantitative variables were analyzed by the Student t test in the case of normal distribution, or Mann-Whitney U-test in the case of a non-normal distribution. To assess the independent effect of various predictors collected at admission on the incidence of good neurologic prognosis at discharge, a logistic regression model was constructed including the variables that showed P<.15 (0.10-0.20) in the univariate analysis, as well as those previously reported to provide prognostic information.16 The variables were entered in the model as a block. Significance level was set at P<.05. All statistical analyses were performed using SPSS 15.0 for Windows (SPSS Inc.; Chicago, Illinois, United States).

Additional tests were carried out to identify the etiologic diagnosis: routine echocardiography in all patients, coronary angiography in 133 (64%), flecainide testing in 5 (all negative), electrophysiologic study in 4 (1 patient was identified and underwent ablation in an accessory pathway; in another, ventricular tachycardia was induced; 2 were negative), and lastly only 1 patient underwent cardiac magnetic resonance, which was inconclusive.

The most common reason for OHCA was some form of ischemic heart disease (71.1%): dilated ischemic cardiomyopathy, non-ST-segment elevation acute myocardial infarction, and most predominantly, in 49% of all patients, ST-segment elevation acute myocardial infarction (STEMI). The cause was considered to be nonischemic dilated cardiomyopathy in 7.4% of cases and hypertrophic cardiomyopathy in 2%. One case of Wolf-Parkinson-White syndrome was diagnosed, 1 acute aortic syndrome, and 1 vasospasm (0.5% each). In 28 (13.7%) patients, no OHCA etiology was identified. The final diagnoses are shown in Figure 1.

Figure 1.

Final diagnosis of study patients. DCM, dilated cardiomyopathy; HCM, hypertrophic cardiomyopathy; NSTEMI, non-ST-segment elevation acute myocardial infarction; STEMI, ST-segment elevation acute myocardial infarction.

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In patients without STEMI, 30.2% had a known cardiomyopathy and only 1 had a poorly functioning implantable cardioverter-defibrillator. The incidence of a family history of sudden death was very low (4%).

Reperfusion treatment was given to 89% of patients with STEMI (primary percutaneous coronary intervention in 79.6% and thrombolysis in 9.3%), with a symptoms-to-balloon time of 178 (5) min. The most common STEMI site was anterior (56.4%), and the anterior descending artery was the most commonly identified culprit artery (57.5%).

Patients had markers of complexity, such as a mean intubation time of 6 days, a tracheotomy rate of 17%, or a mean hospital stay of 24 days.

Of the 204 patients included in the register, 90 (44.1%) were discharged neurologically intact (CPC 1), 12 (5.8%) had mild neurologic deficits (CPC 2), 9 (4.4%) had serious neurologic sequelae that led to dependence (CPC 3), and 10 (5%) continued in a persistent vegetative state (CPC 4); in-hospital mortality was 40.7% (83 patients). The most common causes of death were neurologic complications (50.6%), followed by cardiogenic shock (18%) and infections (17%).

Of the 121 survivors, follow-up information was obtained from 118 (97.5%), with a mean follow-up of 270 days. At 6 months, 82 (69.5%) were still in CPC 1; 13 (11%) in CPC 2; 6 (5%) in CPC 3, and 3 (2.5%) in CPC 4; 14 (11.9%) patients died during follow-up. Of these 14, the cause of death was known in 8 (3, neurologic deterioration; 2, heart failure; 2, recurrence of cardiac arrest; 1, infectious complication). A total of 19 automated defibrillators were implanted. The CPC distribution at discharge and at 6 months and the clinical course are described in Table 3.

Among the 102 patients in CPC 1 or 2 at discharge, 93 (91%) remained in CPC 1 or CPC 2 at 6 months, whereas only 2 (10%) of the 19 patients in CPC 3 or CPC 4 at discharge improved to CPC 2. Mortality was 5.8% in CPC 1 and CPC 2 patients, and 42% in the CPC 3 and CPC 4 group. Most patient deaths occurred during the first month, and vital prognosis was typically good afterwards. In summary, after follow-up, 95/204 (46.5%) were alive and neurologically intact or had few sequelae and 97/204 (47.5%) had died.

No significant differences were found in CPC category between the different hospitals at discharge or during follow-up. Cumulative survival is shown in Figure 2.

Figure 2.

Cumulative cohort survival.

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To identify predictive factors of good vital and functional prognosis at discharge, the population was divided into 2 groups: good prognosis (CPC 1 and CPC 2) and poor prognosis (CPC 3 to CPC 5). A univariate analysis was performed, with the results listed in Table 4.

Based on the available variables at admission with P <.15 in the univariate analysis, a multivariate model was constructed, showing that first recorded rhythm, time to return of spontaneous circulation<30 min, pH on admission n>7, absence of shock, and use of therapeutic hypothermia were the independent factors associated with a good neurologic prognosis (Table 5).

Despite the advantage afforded as a prospective register of all patients who have recovered from OHCA, in our opinion the most important limitation of our study was the difficulty in obtaining specific information related to arrest times and resuscitation maneuver start and duration times. These variables were not measured directly, but rather obtained from out-of-hospital emergency service reports and questioning of relatives and witnesses. Secondly, patient management was not based on a common protocol at all 5 sites, but rather on common guidelines. Moreover, remote follow-up of most patients and the use of the CPC classification did not allow a precise analysis of neurologic status, even though the methodology is recommended by various consensus documents.14 Lastly, because this is a CICU register, patients who died before they reached the hospital and those admitted in other health care areas (intensive care, resuscitation, etc.) were not included and, therefore, the conclusions cannot be extrapolated to the general population.