**2. Incidence of out-of-hospital sudden cardiac death (OHCA)**

The epidemiological, clinical, and pathological characteristics of out-of-hospital SCD are inadequately defined for several reasons.

First, in a significant proportion of clinical research studies, OHCA is not detected because it occurs unexpectedly. Death certificates, medical histories, consultations with relatives, and questionnaires completed by them are reliable sources of

**Figure 1.**

*The most common causes of OHCA (own flowchart).*

#### *Out-of-Hospital Cardiac Arrest in General Population and Sudden Cardiac Death in Athletes DOI: http://dx.doi.org/10.5772/intechopen.101813*

information but often show uncertainty about the cause of death. Second, very few studies consider autopsy-based data that determine the cause of sudden cardiac arrest. In all cases, a complete autopsy, including a toxicological and histopathological examination, should be performed, to investigate the possibility of sudden cardiac death [5]. On the other hand, causes of death based on death certificates are inaccurate and, as a consequence, overestimate the incidence of sudden cardiac arrest [6, 7]. Third, emergency documentation often does not include cases of SCD outside the hospital without an eyewitness, and sometimes these medical records are not available. Last, different SCD definitions are used in the studies, making them difficult to compare.

The incidence of sudden cardiac deaths is usually estimated from studies in developed countries. Fortunately, we still have some reliable data regarding the incidence. OHCA is recorded in about 70% of European countries, but unfortunately, the data record is not uniform. The European Registry of Cardiac Arrest (EuReCa) involved 29 countries with an annual incidence of OHCA in Europe of between 67 and 170 per 100,000 population [1]. The causes show significant variations by gender and age. Incidence is 3–4 times higher in men than in women and increases with age [8].

#### **2.1 Etiology of OHCA**

Ischemic heart disease is the most common cause of out-of-hospital sudden cardiac death. Causes of death also include cardiomyopathy, cerebrovascular disease, and arrhythmia (see **Figure 1**). In contrast, there are cases where the death due to a sudden cardiac arrest occurs outside the hospital, and this is the first appearance of the disease [3, 9, 10].

#### **3. Awareness**

Prevention is separated by definition to primary and secondary prevention. In the case of primary prevention, the goal is to screen patients who are at high risk for SCD but have not had SCD in their lifetime and have not had a malignant arrhythmia. Prevention of sudden cardiac death primarily involves the elimination and treatment of cardiovascular risk factors with smoking cessation, increased physical activity, special diet, treatment of high blood pressure, diabetes, high blood fat, and weight loss in case of obesity. Preventive strategies also aim to define groups or individuals at increased risk of SCD in specific populations. Typically, patients with decreased left ventricular ejection fraction are at high risk for SCD, but a cardiovascular risk assessment of competitive athletes would also be essential.

During secondary prevention, the goal is to further treat patients who have successfully resuscitated after SCD or who have had a malignant arrhythmia and to prevent another arrhythmia.

#### **4. Treatment of circulatory arrest: resuscitation**

The formal professional opinion on resuscitation is published every 5 years by the European Resuscitation Council (ERC) in the form of a recommendation, following the scientific preparation of the International Liaison Committee on Resuscitation (ILCOR). The ERC Directive 2021, published this year, is currently in force [11].

According to the terminology of the ILCOR Consensus on Science with Treatment Recommendations (CoSTR), resuscitation should be initiated in any person who is "unresponsive and absent or abnormal in breathing [12]. This terminology is also included in the most recent basic life support (BLS) directive 2021 [11].
