Death by heart disease

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Death by Heart Disease: An Overview

Sudden Cardiac Death (SCD)

Definition and Prevalence

Sudden cardiac death (SCD) is defined as an unexpected natural death from a cardiac cause within a short time period, typically within one hour from the onset of symptoms, in individuals without any prior condition that would appear fatal. SCD accounts for approximately 300,000 to 400,000 deaths annually in the United States alone, representing about 50% of all cardiovascular disease-related deaths .

Causes and Risk Factors

The primary cause of SCD is often cardiac arrhythmias, which can be due to structural heart diseases such as ischemic heart disease, nonischemic cardiomyopathy, and other structural abnormalities like hypertrophic cardiomyopathy and arrhythmogenic ventricular dysplasia. In some cases, SCD can also result from primary electrical abnormalities of the heart, such as long-QT syndrome or Brugada syndrome.

Demographic Variations

SCD is more common in adults over 35 years, particularly among men, with coronary artery disease (CAD) being the most frequent underlying pathology. However, SCD can also occur in younger individuals, often due to inherited cardiomyopathies, myocarditis, or congenital heart defects .

Ischemic Heart Disease (IHD)

Global Impact

Ischemic heart disease (IHD) remains the leading cause of mortality worldwide, with significant variations in death rates between countries. For instance, age-standardized IHD mortality rates are higher in countries like Ukraine and Kazakhstan compared to the United States, Brazil, and the United Kingdom.

Trends and Risk Factors

Despite being the top cause of death, mortality from IHD has been progressively decreasing in many countries due to declines in smoking and hypertension, although this is counterbalanced by rising obesity and type II diabetes mellitus.

Heart Failure and Mortality

Heart Failure (HF) and Ejection Fraction

Heart failure (HF) is another significant contributor to mortality, with a high proportion of deaths being non-cardiovascular, especially in patients with preserved ejection fraction (EF). In contrast, those with reduced EF are more likely to die from coronary heart disease.

Risk Factors and Trends

Advanced age, male sex, diabetes, smoking, and kidney disease are associated with increased risk of both all-cause and cardiovascular deaths in HF patients. Over time, the proportion of cardiovascular deaths in HF patients with preserved EF has decreased, while it has remained relatively stable in those with reduced EF.

Conclusion

Heart disease, particularly sudden cardiac death and ischemic heart disease, remains a leading cause of mortality globally. While advancements in prevention and treatment have led to declines in mortality rates in some regions, the rising prevalence of risk factors like obesity and diabetes poses ongoing challenges. Understanding the diverse causes and risk factors associated with heart disease is crucial for developing effective strategies to reduce mortality and improve patient outcomes.