While much has been written about life expectancy in the U.S. having hit a relative low point, it is largely young and middle-aged adults that have been most profoundly impacted by this decline. Multiple factors have contributed to the trend, with heart diseases playing a significant role (accounting for more than 4% of the decrease in life expectancy between 2020 and 2021). Specifically, endocarditis, hypertensive heart disease, and heart failure have increased dramatically in young adults, while myocardial infarctions (heart attacks) have increased by 2% per year in adults under the age of 40.¹

Some of the increased incidence of cardiovascular disease and associated deaths is attributable to traditional risk factors, such as obesity and hypertension; however, multiple illicit drugs, including cocaine, opioids, and amphetamines, can have adverse cardiovascular effects, as well.

In light of the ongoing opioid crisis within the United States, with at least 1 in 10 Americans using illicit drugs,² substance use disorder may likely be a contributing factor to these trends in cardiovascular disease deaths.

Endocarditis

Infective endocarditis, also known as bacterial endocarditis, is an infection frequently caused by bacteria entering the bloodstream and leading to inflammation of the inner lining of the heart and the heart valves.³ Such infections occur in both healthcare and community settings. Risks for developing infective endocarditis vary based on the setting in question.

Within the hospital environment, risk is increased with prosthetic valve procedures, vascular catheterizations, hemodialysis, hospitalization, and non-cardiac surgeries. Community-acquired cases are more common in immunocompromised individuals, intravenous drug users, and those with poor dentition, degenerative valve disease, and rheumatic heart disease. From a gender perspective, infective endocarditis is more common in males, with a male to female ratio of 2 to 1.⁴ Recreational intravenous drug use, one of the more common causes of community-acquired infective endocarditis, currently accounts for roughly 10% of all cases.⁵

While deaths due to infective endocarditis decreased for most American adults over the past 20 years, they rose for individuals between 25 and 44 years of age over the same time period. Specifically, they increased by more than 5% per year for those 25‑34 years of age, and more than 2% per year for those 35‑44 years of age. For individuals 45 years of age and older, death rates either remained stagnant or declined over the 20‑year period.

At the same time, there has been a significant increase in substance use disorder in young adults where infective endocarditis was listed as the cause of death.⁶ Consistent with the opioid crisis, there has been a concurrent increase in the prevalence of intravenous drug use in the young adult population – likely increasing their risk to develop, and die from, infective endocarditis.⁷ For example, while the number of Americans who stated they have used cocaine in their lifetime has not experienced a significant change over the past decade, the number of people who have used heroin in their lifetime increased dramatically within the past few years, going from 5.1 million in 2018 to 6.6 million in 2021.⁸

Given the timing of the opioid crisis, and the relationship between intravenous illicit drug use and infective endocarditis, it is possible that the increase in deaths due to infective endocarditis in this population is related to the opioid epidemic. Supporting this theory is the fact that three of the states that have been hit the hardest by the opioid epidemic, Kentucky, Tennessee and West Virginia, experienced significant increases in death rates related to infective endocarditis.

Myocardial Infarction

Myocardial infarction (MI), also known as heart attack, is caused by decrease blood flow to the heart muscle. Myocardial infarctions may occur without any symptoms at all. Alternatively, they may be fatal. The majority of myocardial infarctions are due to coronary artery disease, the leading cause of death in the U.S.⁹ Commonly seen symptoms of myocardial infarction include chest pressure or pain, with possible radiation to the jaw, neck, shoulder, or arm. ECG and biochemical marker changes may be present, as well. Modifiable risk factors for myocardial infarction include smoking, high cholesterol, high blood pressure, obesity, diabetes, poor diet, and lack of exercise. Non-modifiable risk factors include advanced age, male gender, and family history.

While the traditional risk factors mentioned above contribute to myocardial infarction in young adults, nontraditional risk factors, such as substance abuse, immune disease, coronary anomalies, and psychological stressors play a unique role in this population.

While not typically expected in younger age groups, premature myocardial infarction is on the rise in this population and represents a leading cause of death worldwide.¹⁰ The annual proportion of acute myocardial infarction admissions in the 35 to 54‑year-old age group has increased from 27% between 1995 and 1999 to 32% between 2010 and 2014. Similarly, the percentage of very young individuals (less than 40 years old) experiencing an MI increased 1.7% per year between the years of 2007‑2016. While 80‑90% of patients who had a myocardial infarction at a young age have at least one risk factor prior to their MI, this is often unrecognized and untreated.¹¹

Importantly, while some of the nontraditional risk factors listed above may be playing a role in this trend, it has been well documented that many of the modifiable traditional risk factors, such as high blood pressure, high cholesterol, and diabetes, have increased in prevalence within the younger age groups. With respect to smoking in particular, while prevalence within the general population has decreased over time, it has increased within the population of young MI patients. Importantly, those who quit smoking post‑MI had a substantially reduced risk of recurrent events.¹² Similarly, substance abuse is a well-known risk factor for myocardial infarction and is increasingly prevalent within the young MI population.

Summary

Younger adults have been some of the hardest hit by declining life expectancy in the U.S., and heart disease, including infective endocarditis and myocardial infarction, has been a contributor to this trend. Traditional risk factors for heart disease, such as high blood pressure and cholesterol, have increased in prevalence. However, in light of the ongoing opioid crisis within the U.S., substance abuse, a well-known nontraditional risk factor for heart disease, may likely be playing a role, as well.

Whether due to traditional or nontraditional causes, the onset of such risk factors at early and earlier ages increases the cumulative exposure over time.