It's well-known that smoking is bad for the heart and other parts of the body, and researchers now have chronicled in detail one reason why - because continual smoking causes progressive stiffening of the arteries.
In fact, smokers' arteries stiffen with age at about double the speed of those of non-smokers, Japanese researchers have found.
Stiffer arteries are prone to blockages that can cause heart attacks, strokes and other problems.
"We've known that arteries become more stiff in time as one ages," said Dr William B. Borden, a preventive cardiologist and assistant professor of medicine at Weill Cornell Medical Centre in New York City. "This shows that smoking accelerates the process. But it also adds more information in terms of the role smoking plays as a cause of cardiovascular disease."
For the study, researchers at Tokyo Medical University measured the brachial-ankle pulse wave velocity, the speed with which blood pumped from the heart reaches the nearby brachial artery, the main blood vessel of the upper arm, and the faraway ankle. Blood moves slower through stiff arteries, so a bigger time difference means stiffer blood vessels.
Looking at more than 2,000 Japanese adults, the researchers found that the annual change in that velocity was greater in smokers than non-smokers over the five to six years of the study.
Smokers' large- and medium-sized arteries stiffened at twice the rate of non-smokers', according to the report released online April 26 in the Journal of the American College of Cardiology by the team from Tokyo and the University of Texas at Austin.
That's no big surprise, said Borden, noting there's definitely a dose-response relationship. "The more smoking, the more arterial stiffening there is per day."
The study authors measured stiffening by years, not by day, but the damaging effect of smoking was clear over the long run.
The finding gives doctors one more argument to use in their continuing effort to get smokers to quit, said Dr David Vorchheimer, associate professor of medicine and cardiology at Mount Sinai Medical Center in New York City.
"One of the challenges that physicians face when trying to get people to stop smoking is the argument, 'Well, I've been smoking for years and nothing has happened to me yet,'" Vorchheimer said. "What this study emphasises is that the damage is cumulative. The fact that you've gotten away with it so far doesn't mean you'll get away with it forever."
The stiffening of arteries is "one of the earliest and most subtle changes that occur" in smokers' bodies, Vorchheimer said. "Some people's arteries can be safe for a few years. The good thing about that is the possibility that the damage will heal if you give up smoking."
Another notable aspect of the study was the analysis of the effect of smoking on C-reactive protein, a molecular marker of inflammation that appears to play a role in cardiovascular disease. The study found no relationship between blood levels of C-reactive protein and arterial stiffening.
That finding adds one more piece to the puzzle of C-reactive protein and cardiovascular disease that researchers are trying to assemble, Borden said. "We're still trying to understand the role of CRP, whether it's a cause or a marker of other factors that lead to cardiovascular disease," he said. - (Ed Edelson/HealthDay News, April 2010)