Clearing the Air on Smoker’s Paradox

Interview | Ajay Kirtane, MD

At the ACC.15 64th Scientific Session & Expo in beautiful San Diego, CA, CardioSource WorldNews spoke with Ajay Kirtane, MD, FACC, associate professor at Columbia University Medical Center and New York Presbyterian Hospital. Kirtane is the author of the editorial commentary that accompanied a paper in the March 24th, 2015 issue of JACC, “Smoking is Associated with Adverse Clinical Outcomes in Patients Undergoing Revascularization With PCI or CABG: Insights From the SYNTAX Trial at the Five-Year Follow-Up.”

The idea that smoking is bad for you should be a no-brainer, but Kirtane further elaborates with his editorial comment, “Clearing the Air on the Smoker’s Paradox.”

CARDIOSOURCE WORLDNEWS: Describe the smoker’s paradox, because it seems a little bizarre.
AJAY KIRTANE, MD, FACC: I think it’s been known for quite some time now, and it’s actually used in epidemiology classes to talk about the influence of confounders.

There are other things that can explain the association that you see besides what you’re actually measuring. What was shown in prior studies is that smokers, for whatever reason, when they present with heart attack, had a better prognosis than non-smokers, and some of this is due to the fact that they’re, on average, ten years younger, they have less comorbidities, and, in some cases, respond better to some of the therapies we administer to them than non-smokers. That doesn’t mean smoking is a good thing.

The main paper is by Zhang et al., and it’s an analysis of the SYNTAX trial. What did they do? What did they find?
SYNTAX is a trial that looked at PCI or surgery for patients with complex coronary artery disease—typically a three vessel disease or left main coronary disease. What the authors showed is smoking as measured over time longitudinally, and that’s really important. It wasn’t just at the initial index presentation. It was over time looking at what happened with smokers. Did they quit? Did they go back on it? Anybody who continued to smoke had a markedly increased risk of myocardial infarction and adverse outcomes.

That’s really good news for the people who have been a little confused and are perhaps like, “Well, you know, it could be okay if they’re smoking.”
Certainly for these patients with complex diseases, we have to be assiduous in terms of trying to get them off [smoking]—especially because the authors found that a lot of these patients who stopped after a bypass surgery…they resume later. And so for those patients we have to make a continual effort to really challenge them to not smoke because it’s clearly bad for their health.

Doctors are very busy with today’s demands. They’re busier than ever, but it is still important to keep on the chart in front of you the fact they’re a smoker and [to ask questions such as] “Can you stop? Are you ready to stop? Can we help you stop?”
Those, and “Have you started again?” If you know somebody who was a smoker, “Are you back on it again?” It’s an important question and one of the [points] we try to make in the editorial.

I’m an interventional cardiologist, and my surgical colleagues help a lot of patients. But if you do these basic fundamental lifestyle things, especially over time, you can have a greater impact on patients sometimes than even doing the procedures themselves.

Will we lose the smoker’s paradox as a teaching moment, or will we still be able to point out the fact that there are some questions? Does this answer it?
No. I think we’ll always have it as an example, and it’s a good one. It’s a good epidemiological thing. It helps people understand that, sometimes, when we measure associations in the literature, there can be other mechanisms underlying the association, and not just what you’re measuring.

Zhang YJ, Iqbal J, Klaveren DV, et al. J Am Coll Cardiol. 2015;65(11):1107-15.

Clinical Topics: Prevention, Smoking

Keywords: CardioSource WorldNews, ACC Annual Scientific Session, Coronary Artery Disease, Smoking, Myocardial Infarction, Tobacco

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