Teens Who Smoke Face Risk of Cardiac Damage by Their Mid-20s

People who smoke cigarettes during childhood, then continue to do so, are more likely to develop echocardiographic markers of cardiac damage by the time they reach their mid-20s, an observational analysis shows.

The findings were published online yesterday as a brief report in the Journal of the American College of Cardiology.

Investigator Andrew O. Agbaje, MD (University of Eastern Finland, Kuopio), told TCTMD that the data offer several key takeaways.

To start, “we were able to identify the most important time when smoking is picked up, as children grow to young adults, and that time was between the age of 13 and 17,” he said, adding that this period merits special focus in prevention measures. Moreover, most of the kids who started smoking continued to do so through their twenties.

Later in life, too, there are implications. Studies have consistently shown that people exposed to cigarette smoke, whether they “are actively or passively smoking, eventually may come down with cardiac disease, maybe about the age of 40, 45, 50,” said Agbaje. “So that understanding, in a way, gives some people almost a ‘free ticket’ to keep on smoking, because they are not yet at 45,” he explained. With that misperception of risk, they say: “When I get to 45, maybe I’ll stop at that time. I am able to cope with this situation.”

What the data show is that “it’s dangerous to smoke at all, because the damage could have been done 20 years earlier and it might be irreversible. . . . Smoking in childhood can cause cardiac damage two decades before a heart attack.” Agbaje stressed.

Kunihiro Matsushita, MD, PhD (Johns Hopkins Bloomberg School of Public Health, Baltimore, MD), commented on the new results for TCTMD. The study is “unique, because they have a relatively large sample size with smoking data from age 10 through age 24,” as well as echocardiographic measures in most of the cohort, he said.

In a 2022 paper, also published in JACC, Matsushita and colleagues showed cigarette smoking’s association with heart failure can linger for decades even after people quit. “I think prevention is key. . . . We demonstrated the impact of smoking can last up to 30 years,” he noted. “So that means that [it’s] best not to start, right? Because once you start, you accumulate exposure, then it takes time to return to [your] baseline risk.”

Smoking in childhood can cause cardiac damage two decades before a heart attack. Andrew O. Agbaje

Agbaje’s analysis included 1,931 children (mean age 10.6 years at enrollment; 62.7% female) who participated the England-based Avon Longitudinal Study of Parents and Children (ALSPAC) and had complete smoking and angiographic measures by age 24. Participants answered questionnaires at each follow-up visit over the years as to whether they’d smoked within the prior 30 days.

Based on those answers, the prevalence of smoking was 0.3% at age 10 and 1.6% at age 13. It then jumped to 13.6% at age 15, 24% at age 17, and 26.4% at age 24.

Sixty percent of those who started smoking in their adolescent and teen years continued to smoke in their mid-20s. LV hypertrophy rose in prevalence from 2.8% at age 17 to 7.5% at age 24 among these persistent smokers, while LV diastolic dysfunction rose from 10.4% to 16.9%.

Agbaje then adjusted for sex as well as age, high-sensitivity C-reactive protein, heart rate, systolic blood pressure, fasting insulin and glucose, family history (hypertension, diabetes, high cholesterol, and vascular disease), socioeconomic status, sedentary time, physical activity, fat and lean mass, and lipid levels.

By age 24, persistent smoking—compared with never smoking or having quit—was associated with increased LV mass indexed for height as well as with greater likelihoods of LV hypertrophy (OR 1.52; 95% CI 1.39-1.66), high relative wall thickness (OR 1.38; 95% CI 1.26-1.51), LV diastolic dysfunction as measured by mitral E/A ratio (OR: 1.33; 95% CI 1.22-1.46), and high LV filling pressure as measured by the E/e′ ratio (OR 1.35; 95% CI 1.25-1.45).

I think prevention is key. . . . Because once you start, you accumulate exposure. Kunihiro Matsushita

While the study of the ALSPAC data is observational, this design is really the only option given that it would be impossible to do a randomized trial that asks people to start smoking, said Agbaje.

Matsushita pointed out that smoking doesn’t occur in isolation but may be impacted by the surrounding environment—the factors that enable a 10-year-old to pick up their first cigarette. He said it’s unclear, based on the short format of the paper, exactly how researchers adjusted for socioeconomic status or if they looked at other social determinants of health.

Both Agbaje and Matsushita agree it makes sense that early smoking would have long-term consequences.

As the paper notes: “Cigarette smoke has been associated with endothelial dysfunction and inflammation-induced atherosclerotic processes, abnormal lipid metabolism, increased myocardial hypoxia and oxygen demand, decreased cerebral oxygen availability, and altered metal homeostasis, which might induce chronic diseases.”

Whether or not the cardiac injury observed in the ALSPAC dataset will have a long-term impact on CV event risk isn’t certain, though. “I think the data to answer that question may be limited,” said Matsushita. “But looking at the robust evidence about left ventricular myocardial index, and then left ventricle hypertrophy in adults, it seems reasonable to expect that greater amount of left ventricle mass at younger age will translate to poorer prognosis.”

To this end, the two physicians say it’s worth asking for details about smoking history—even if it’s decades earlier—during clinical encounters.

“They should be specific,” Agbaje said. “They should say, ‘Please, can you remember if you smoked when you were a teenager?’ That is better than just, ‘Do you have a history of smoking?” Matsushita, for his part, suggested it might be best to characterize the level of smoking as pack-years, a metric that captures intensity and duration, both of which matter.

A looming question, one that’s not yet possible to answer, is whether vaping and other alternatives to combustible cigarettes carry harms similar to what this analysis shows. These products are growing in popularity in adolescents and young adults. Importantly, they still contain nicotine, which is addictive and known to cause irregular heartbeats, said Agbaje.

Yet because vaping has only existed for about a decade, long-term data aren’t yet available. If it turns out that these newer products also cause cardiac damage, that news won’t come as a surprise based on what’s been seen so far, he added.

Going forward, “governments must be bold” in holding tobacco companies more accountable when they target young people, Agbaje urged. “You just have to speak the truth to power. . . . We can't rob the future [from] brilliant and wonderful kids.”