Early smoking causes structural and functional heart damage

Cigarette smoking from childhood into early adulthood is associated with an increased risk of premature cardiac injury, according to a study published today in JACC, the flagship journal of the American College of Cardiology. This early damage to the structure and function of the heart can also significantly increase the chance of future cardiovascular (CVD) mortality in mid-life.

“Our goal is to provide data for policymakers, clinicians, and public health practitioners on crucial timing for preventing smoking and its early consequences in youth,” said Andrew Agbaje, MD, MPH, PhD, lead and senior author of the study and an associate Professor of Clinical Epidemiology and Child Health at the University of Eastern Finland, Kuopio, Finland. “Parents and caregivers must lead by example and government agencies should be bold to address the preventable heart disease risk by creating a smoke and nicotine-free country. Raising tobacco taxes is insufficient because the cost of health care due to smoking-related diseases twice exceeds tobacco tax profits. Why should we pay for what is killing our teenagers softly?”

Researchers from the University of Eastern Finland collaborating with the University of Bristol used the Avon Longitudinal Study of Parents and Children (ALSPAC) birth cohort data to examine the impact of tobacco smoking during growth from childhood to young adulthood and its association with structural and functional cardiac injury.

Cardiac injury refers to damage to the heart muscle, or the myocardium, and can occur from causes such as ischemia (reduced blood flow), inflammation, trauma or chronic diseases. Cardiac mass increase is the increase in size or weight of the heart and is often associated with cardiac hypertrophy, or the thickening of the heart muscle walls. Both conditions can affect heart function. Adolescent smoking has been associated with vascular injury in adolescence and CVD mortality in midlife. However, studies of cardiac structure and function in healthy children are scarce, since cardiac injury in childhood is usually due to rare clinical events.

The analysis included 1,931 young adults with complete smoking and echocardiographic measures at 24 years. The prevalence of smoking was 0.3%, 1.6%, 13.6%, 24%, and 26.4% at ages 10, 13, 15, 17, and 24 years, respectively, and 60% of those who initiated smoking in childhood continued smoking at 24 years.

Researchers found that tobacco smoking from age 10 to 24 years was associated with 33% to 52% odds of premature structural and functional cardiac injury. Additionally, it was associated with cardiac mass increase, even after controlling for competing risk factors.

Key study results include:

• Left ventricular (LV) hypertrophy prevalence increased from 2.8% to 7.5% at age 24.
• Left ventricular diastolic (LVD) dysfunction prevalence increased from 10.4% to 16.9% at age 24.
• Increased risk of high relative wall thickness (RWT) and high left ventricular filling pressure (LVFP).
• Increased left ventricular mass index (LVMI) in both unadjusted and adjusted models from ages 17 – 24 years.

“The increase of cardiac mass structure in just a few years of smoking should convey how dangerous the consequences are for people who continue to smoke from a young age,” Agbaje said.

“This study shows that teen smoking doesn’t just increase the risk of heart disease later in life – it causes early and lasting damage to heart muscle and function,” said Emily Bucholz MD, PhD, MPH, Assistant Professor of Pediatrics at the University of Colorado School of Medicine and Associate Editor of JACC. “It’s a wake-up call for prevention efforts to protect young hearts early.”

Limitations of the study include insufficient data on socio-environmental influences, including parental smoking, friends and peer smoking, or consuming alcohol. Also, cotinine levels, which help quantify true nicotine exposure, were unavailable to analyze. Lastly, most study participants were Caucasian, which may make findings ungeneralizable to other racial groups.