Cardiovascular diseases is the primary cause of death worldwide, responsible for about 17.9 million casualties annually. Among these, sudden cardiac arrest (SCA) emerging as an increasing health challenge, especially in younger populations. A large number of SCA cases occur in individuals under 50, where inherited arrhythmias and structural cardiac disorder, like hypertrophic cardiomyopathy are predominant causes, while coronary artery disease is the major cause in older adults. In spite of advancements in medicine, survival rate after SCA remains critically low. Early detection by family screening and genetic testing, combined with public awareness and education is vital to reduce the risk of sudden tragedy. This review synthesizes evidence on epidemiology, trends, and preventive strategies, highlighting the need to integrate precision medicine, campaigns for public health and focused awareness programs to counter the growing global burden of SCA among young individuals.
Highlights
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Sudden cardiac arrest (SCA) is a rising global health issue, especially among younger individuals.
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Inherited arrhythmias and hypertrophic cardiomyopathy are leading causes of SCA in the young.
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Coronary artery disease dominates in older SCA cases.
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Global registries are vital for equitable research and policy.
Central illustration
Cardiovascular diseases (CVD) consist of large number of disorders that effect blood vessels and heart, such as stroke, coronary artery disease, and heart failure. They remain the major cause of death worldwide and contributor to global noncommunicable disease burden. The occurrence of CVD is outcome of environmental, genetic, and behavioral risk factors such as high cholesterol levels, high blood pressure, smoking, poor dietary habits, diabetes, and sedentary lifestyle patterns.
According to the World Health Organization (WHO) 2025 report, CVD is the leading cause of death worldwide, accounting for more than 20 million deaths annually, nearly one-third of all global mortality. Over the past decade, deaths resulting from CVD have boosted roughly by 12.5%, with its escalating impact. Among the numerous conditions, stroke and ischemic heart disease comes as major causes, accounting for 49% and 33% of the total global burden. Low- and middle-income countries (LMICs) remain highly affected, often experiencing high mortality at younger ages due to less healthcare access and preventive strategies.
In parallel, many regions within this group particularly Eastern Europe and large parts of Asia (Central, East, and South) are witnessing a rising number of CVD cases, driven by constrained resources and ageing populations. This growing burden is mirrored in the Americas (Latin, North, and Caribbean), where CVD accounted for an estimated 2 million deaths and 43 million disability-adjusted life years (DALYs) lost in 2021 In 2022, there were 19,171 deaths in the United States where sudden cardiac arrest (SCA) was the primary cause, while it was mentioned as a contributing factor in 417,957 total deaths worldwide. In 2023, global statistics showed that the majority (71.0%) of adult out-of-hospital cardiac arrests (OHCA) occurred at home or in residential settings. Other locations included public areas (18.2%) and nursing homes (10.7%). These observations underscore both the substantial burden and the heterogeneous distribution of cardiovascular events worldwide ( Figure 1 ).
Global cardiovascular mortality, 2021. The choropleth map illustrates the proportion of deaths associated to cardiovascular diseases among different regions. High percentages are observed in Eastern Europe, Central Asia, the Middle East, and South Asia, indicating a higher relative mortality burden in these areas.
CVD arise from a variety of causes, which can be broadly categorized as major and minor contributors. The major causes, accounting for approximately 70% to 80% of total cases, primarily include coronary heart disease, cerebrovascular disease, and peripheral arterial disease. Coronary heart disease is the most prevalent form and occurs due to narrowing or blockage of the blood vessels that supply oxygen-rich blood to the heart, often resulting in chest pain, heart attacks, and heart failure. Damage to the blood vessels that carry blood to the brain is known as cerebrovascular disease, and it can result in strokes or transient ischemic episodes, often known as mini-strokes. Peripheral arterial disease affects the arteries responsible for blood supply to the limbs, commonly leading to pain, numbness, or even tissue death due to restricted blood flow.
In comparison, 20% to 30% of all cardiovascular disease accounts for minor causes and are associated with infections or congenital abnormalities. One of them causes long-term damage to the heart valves and develop as a consequence of untreated rheumatic fever caused by Streptococcal infection. Others include structural abnormalities present at birth and are characterized as congenital heart diseases. Their severity ranges widely, and many cases require surgical correction. Furthermore, conditions in which blood clots form in the deep veins, often in the lower limbs, and may go to the lungs, posing serious health risks are regarded as thromboembolic disorders such as deep vein thrombosis (DVT) and pulmonary embolism (PE). Cardiovascular diseases impose extensive and multifaceted burden on global health collectively both by major and minor etiological factors ( Figure 2 ).
Major categories of cardiovascular diseases. This figure represents the major forms of cardiovascular disorders, outlining the key clinical features associated with each condition.
Sudden cardiac arrest in athletes is striking because they are regarded as the epitome of health and discipline. In spite of following training schedules, optimal physical conditioning, and healthy lifestyles, they are not immune to hidden cardiac vulnerabilities. Recent data shows that SCA remains 1 of the leading causes of mortality in sports, emerging without warning during training or competition times.
Among younger individuals, SCA been viewed as a minor contributor within the spectrum of cardiovascular diseases. However, in recent years SCA has emerged as a major and rapidly escalating public health concern, largely because of its abrupt onsets and growing incidence among younger and seemingly healthy individuals. Unlike other cardiovascular disorders that progress gradually and allow time for medical intervention but SCA often strikes without warning and leads to death within minutes, making it disproportionately impactful despite representing a smaller share of overall CVD cases. This phenomenon is linked to several other cardiovascular abnormalities such as inherited arrhythmogenic syndromes, various cardiomyopathy, and congenital disorders of the coronary arteries. These conditions can only be diagnosed after occurrence of sudden cardiac arrest event.
A recent study from Australia and New Zealand shows that SCA in young is a major concern, with males comprising nearly 70% of the reported cases. In Europe, population-based studies from Denmark have reported incidence cases of 54 to 58 OHCA per 100,000 people/year, In United Kingdom, the National Cardiac Arrest Audit identified over 30,000 OHCAs annually. The table summarizes SCA cases and death caused across various countries and age groups. Incidence are expressed as cases per 100,000 person/years, among different populations with varying sizes and follow-up durations. Also, these figures represent incidence rates from cohorts or registries rather than national death counts. Variations in incidence rates reflect differences in age range studied, methodological approach (retrospective vs prospective), and case (SCD alone and combined SCA+SCD). For example, higher incidence is reported in France, which includes all age groups, whereas other studies focus on children and adults. Overall, the table highlights consistently low but clinically significant incidence of SCA/SCD in younger populations ( Table 1 ).
Table 1
Summary of population-based studies on sudden cardiac arrest (SCA) and sudden cardiac death (SCD) in young individuals
| Country | Year of publishing | Study design | SCD or SCA+SCD | Years studied | Age range | Incidence (per 100,000/year) | Cohort size |
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| Iceland | 2006 | Retrospective cohort | SCD | 1974 to 2004 | 12 to 35 | 2.3 to 2.6 | Population aged 12 to 35(census based) |
| USA and Canada | 2009 | Prospective cohort | SCA+SCD | 2005 to 2007 | 12 to 19 | 1.1 to 1.3 | ∼23.7 million |
| USA | 2009 | Prospective population based | SCA+SCD | 2002 to 2005 | 10 to 14 | 0.8 to 1.0 | 1.2 million |
| UK | 2009 | Retrospective cohort | SCA | 2002 to 2005 | 1 to 34 | 1.4 to 1.8 | Population aged 1 to 34 in the UK |
| Denmark | 2010 | Retrospective cohort | SCD | 2000 to 2006 | 1 to 35 | 1.2 to 3.7 | ∼5.4 million |
| Norway | 2010 | Retrospective cohort | SCD | 1979 to 1998 | 15 to 34 | 1.5 to 2.0 | Population aged 15 to 34 in Norway (Registry based) |
| USA | 2011 | Retrospective cohort | SCA+SCD | 1986 to 2005 | 2 to 24 | 1.6 to 2.2 | 1.2 million |
| Ireland | 2011 | Retrospective cohort | SCD | 2005 to 2007 | 15 to 35 | 2.8 to 3.3 | Population aged 15 to 35 years in Ireland (census based) |
| France | 2011 | Prospective | SCA+SCD | 2005 to 2010 | 12 to 75 | 4.6 to 5.0 | 50.9 million |
| USA | 2012 | Prospective population based | SCA+SCD | 1980 to 2009 | 0 to 35 | 2.1 to 2.4 | Population aged 0 to 35 years (census based) |
| Ontaria, Canada | 2013 | Retrospective cohort | SCD | 2008 | 2 to 40 | 1.7 to 2.0 | Population aged 2 to 40 years (censusbased) |
| Denmark | 2014 | Retrospective cohort | SCD | 2000 to 2006 | 1 to 18 | 0.5 to 0.7 | 13 million |
| USA | 2004 | Retrospective cohort | SCD | 1977 to 2001 | 18 to 35 | 1.3 | 6.3 million |
This review emphasizes that cardiac arrest in the young is an underestimated global problem, driven largely by inherited electrical and structural heart disorders. By current evidences on epidemiology and diagnostic limitations, the review points out the urgent need for improved screening, standard registries and early-detection stratification which focus on better prevention strategies are essential to reduce no. of deaths in young age group.
Etiologies of SCA
Cardiac Arrest typically results from prior structural heart abnormalities. Ischemic coronary disease is 1 of leading cause of cardiac arrest, accounting for approximately 70% of cases. Irrespective of the age, the causes of sudden cardiac death (SCD) can be broadly categorized into 2 groups: coronary/cardiac and non–coronary/non–cardiac causes. Coronary and other primary causes of cardiac arrest typically show well-defined signs such as ischemic changes on electrocardiogram, making them easier to identify diagnostically, whereas non–coronary and non–cardiac causes often present with subtle or atypical symptoms which are difficult to detect without high clinical supervision or additional testing. Coronary or cardiac causes can include coronary heart disease, myocardial infarction, arteriosclerosis and atherosclerosis. Non–coronary or non–cardiac causes include structural conditions like hypertrophic and dilated cardiomyopathy, valvular heart disease, and congenital heart disease, as well as nonstructural conditions like genetically acquired arrhythmias (e.g., Brugada syndrome and LQTS). Additionally, non–cardiac causes can stem from neurological disorders (e.g., intracranial hemorrhage) and metabolic disturbances, including electrolyte and endocrine imbalances.
Coronary causes
Coronary artery disease/coronary heart disease
Coronary artery disease (CAD) occurs when cholesterol deposits and inflammation lead to the formation/deposition of atherosclerotic plaques in the coronary and other systemic blood vessels. When this plaque ruptures, particularly in smaller arteries like 1 supplying blood to heart, blood flow is blocked to tissues which limits oxygen delivery. The injury of the myocardial tissue resulting from ischemia, interferes with the heart conduction, contractile function and normal rhythm. While CAD is a major contributor to sudden cardiac death, it is age-dependent, and less common cause in individuals under 40. Coronary heart disease symptoms can vary greatly among individuals, and about 1 in 20 adults over 20 have the condition, often remaining unaware until they experience chest pain, a heart attack, or cardiac arrest. The buildup of plaques can lead to different types of coronary heart disease, including obstructive coronary artery disease, where a large artery is blocked by 50% or more, and nonobstructive coronary artery disease, where the blockage is less than 50%. Additionally, coronary microvascular disease can occur, where the small blood vessels within the heart muscle are affected, and this is more common in women. Fortunately, coronary heart disease is often preventable with a heart-healthy lifestyle and medication, and in some cases, plaque buildup can be reversed or stopped.
Myocardial infarction
“Myocardial infarction (MI), or heart attack, results from a sudden reduction or cessation of blood flow to the heart muscle, most often due to atherosclerotic plaque rupture and coronary artery occlusion. This interruption of oxygen delivery causes sustained ischemia, leading to myocardial injury and necrosis, making MI a leading cause of mortality in the United States and globally. Patients typically report chest discomfort or pressure, which can radiate to the jaw, neck, shoulder, or arm. Diagnosis is based on clinical symptoms, ECG changes consistently with ischemia, and cardiac biomarkers elevation such as troponins.”
Arteriosclerosis
Arteriosclerosis i.e., “hardening of the arteries,” is progressive stiffening of arteries and arterioles throughout the body. This occurs when vascular smooth muscle cells are replaced by collagen and calcium deposits which accumulates with age, reduces the elasticity of the arteries. Unlike atherosclerosis, arteriosclerosis does not involve lipid buildup or inflammatory processes within the internal layer.
Non–coronary causes
Cardiomyopathies
Cardiomyopathies are heart muscles disease that can lead to sudden cardiac death, heart failure, and arrhythmias. The 3 main types mentioned are:
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Dilated cardiomyopathy (DCM): It is characterized by enlargement of mostly the left or both ventricles, along with impaired systolic function in the absence of hypertension or valvular disease. DCM is a leading cause of heart failure and affects approximately 1 in 250 to 1 in 500 people. While it can occur at any age, symptoms typically manifest in the third or fourth decade of life.
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Hypertrophic cardiomyopathy (HCM): Marked by thickening of the heart muscle, which can obstruct blood flow and increase the risk of arrhythmias. HCM is characterized by a wall thickness greater than 14 mm in segments of the left ventricle, as detected by imaging techniques, without any abnormal loading conditions. Epidemiological studies estimate the prevalence of HCM to be between 1 in 200 and 1 in 500 people, with mortality rate of around 1.4%.
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Arrhythmogenic right ventricular cardiomyopathy (ARVC): A condition where the heart muscle in the right ventricle is replaced by fatty tissue. It is a genetic disorder leading to arrhythmias wherein typically, the right ventricle is affected, but the left ventricle can also be involved. The condition is part of a broader category of arrhythmogenic cardiomyopathies, and some experts prefer the term “arrhythmogenic cardiomyopathy” to reflect the potential for biventricular or left ventricular involvement.
Myocarditis
Myocarditis is an uncommon, yet serious disorder characterized by inflammation of myocardium (heart layer), which weakens the heart muscle and interfere with cardiac electrical signaling, ultimately affecting its ability to pump blood efficiently. A wide range of factors can trigger myocarditis, including viral, bacterial, and fungal infections, as well as certain medications, autoimmune conditions, and exposure to toxic agents. The disease may present in an acute form, resolving within a short period, or progress into a subacute or chronic state that persists for several weeks or months. In severe cases, myocarditis can lead to heart failure or death.
Inherited arrhythmia syndromes (LQT, BrS, CPVT, ERS)
Inherited arrhythmias are a group of disorders that can cause life-threatening heart rhythms even in the absence of structural heart disease. These conditions can be asymptomatic or lead to sudden cardiac death, often affecting young, healthy individuals. In some studies mutations in genes that code for ion channels and related proteins in heart have been identified as the cause of these disorders, increasing the risk of ventricular arrhythmias.
Inherited arrhythmias include several specific conditions, such as:
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Long QT syndrome (LQTS)-Long QT syndrome is a heart rhythm disorder which is autosomal dominant and is used to describe an issue with the pattern on an ECG. The QT interval is the electrical activity that takes place in between the Q and T waves. The ventricles, the heart’s lower chambers, exhibit electrical activity throughout this time. Typically, a third of each pulse cycle passes between the Q and T waves. However, the QT interval is longer than usual in those with LQTS.
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Short QT syndrome (SQTS)-The condition is also autosomal dominant. SQTS genotypes 1 to 3 are the opposite of LQTS and are caused by a gain-of-function mutation in cardiac potassium channels. A notable shortening of the QT interval (<320 ms) and faster atrial and ventricular repolarization are caused by increased potassium efflux at various phases of the action potential. On the other hand, loss-of-function mutation in the L-type cardiac channel is the cause of SQTS genotypes 4 and 5. The QRS complex morphology is similar to that of Brugada syndrome, and the QT interval is modestly shortened (<360 ms) due to decreased calcium influx during the action potential’s plateau phase.
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Brugada syndrome (BrS)-It is a rare genetic heart condition that affects how your heart beats. It’s named after 2 Spanish doctors, Pedro and Josep Brugada, who first discovered it in 1992. A person with this syndrome experiences fast ventricular movements. This can be really dangerous and might cause them to faint, have seizures, or most seriously experience sudden cardiac death. These episodes often happen during sleep or when the person is physically active.
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Catecholaminergic polymorphic ventricular tachycardia (CPVT)-It is a condition that causes episodes of fainting during physical activity or intense emotions due to abnormal heart rhythms. CPVT represents stress-triggered electrical instability, where physical exercise or emotional stress increases catecholamine levels and provokes ventricular arrhythmias, even though the resting ECG is normal. In contrast, Brugada syndrome is characterized by resting-state electrical instability, at rest or during sleep and often unmasked by fever or certain medications, along with a characteristic abnormal ECG pattern. These irregular rhythms can become life-threatening and may lead to ventricular fibrillation, which ultimately can lead to sudden death if not treated immediately. Symptoms can begin in childhood, around ages 7 to 12, but may appear later in life. If left untreated, CPVT is highly threatening, with a significant risk of cardiac arrest and sudden death, which can sometimes be the first sign of the conditions.
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Early repolarization syndrome (ERS)-Early repolarization (ER) is a frequent finding on an electrocardiogram (ECG) and was long regarded as a benign pattern. More recent research, however, indicates that it may be linked to increase risk of sudden cardiac death. ERS represents a specific clinical condition in which ER is associated with fatal cardiac arrhythmias. While ER itself is relatively common, with an estimated prevalence of approximately 0.5 cases per 100,000 individuals. Genetic testing is not typically used for ERS, and those diagnosed are at high risk of recurrent arrhythmias, up to 40%.
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Idiopathic ventricular fibrillation (IVF)/idiopathic left ventricular hypertrophy-It is a condition where ventricular fibrillation occurs without a known cause, despite thorough testing and ruling out other arrhythmia syndromes. The exact prevalence of IVF is hard to determine. Its underlying mechanisms are unclear, but research suggests that in some cases, abnormal premature ventricular contractions may trigger life-threatening arrhythmias like ventricular fibrillation.
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Wolff-Parkinson-White syndrome-Wolff-Parkinson-White (WPW) syndrome is a cardiac condition that is congenital and arises from symptomatic and potentially fatal arrhythmias through aberrant cardiac electrical conduction via an auxiliary route. A short PR interval and a prolonged QRS with an initial upstroke (also known as a “delta” wave) in the presence of sinus rhythm are the hallmark electrocardiographic (ECG) findings of the WPW pattern or pre-excitation. The term WPW syndrome is reserved for an ECG pattern consistent with the above describe findings along with the coexistence of a trachyarrythmia and clinical symptoms of tachycardia such as palpitations, episodic light headedness, presyncope, syncope, or even cardiac arrest.
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Commotio-cordis- Commotio cordis is a type of ventricular fibrillation triggered by a sudden, forceful impact to the chest, without any underlying structural damage to the heart or nearby tissues. The term commotio cordis, derived from Latin meaning “agitation of the heart,” reflects the believed mechanism in which the forceful blow causes abrupt mechanical disruption of the heart muscle, leading to abnormal electrical activity and an unstable heart rhythm.
These above conditions are all characterized by abnormal heart rhythms that can be life-threatening ( Figure 3 ).
