Half of habitual smokers who experience myocardial infarction (MI), stroke or other adverse cardiovascular events continue to smoke cigarettes after hospitalization, a study from South Korea has found.

The research, published this October in the journal PLOS One, analyzed the likelihood of smoking cessation in a population of 1,700 Koreans who had experienced an adverse ischemic heart disease (IHD) event between 2003 and 2012. Yoo Kyoung Lim and co-authors wrote they focused on the topic because, while evidence exists that continuing to smoke following a cardiovascular event can double the chances of a recurrence, population-level data detailing smoking behavior changes among IHD-diagnosed patients is lacking.

The World Health Organization reported in 2012 that 10 percent of all deaths due to cardiovascular disease (CVD) were a direct result of smoking. According to Lim et al., persistent smoking or smoking relapse doubles the risk of recurrence and mortality in stroke survivors and doubles the risk of mortality in IHD survivors. Previous studies have suggested quitting tobacco is responsible for a 36 percent reduction in risk of all-cause mortality for patients living with IHD—a significant number when compared to the 29 percent decrease that comes with the intake of statins or the 15 percent risk reduction from taking aspirin.

Lim and colleagues drew data from the Korean National Health Insurance sample cohort database, which encompasses nearly all of the South Korean population. Information was derived from questionnaires filled out by patients, and subsequent interviews by healthcare providers.

The researchers found that, of the 486 patients studied who were smokers before their CVD event, 240—49.4 percent—were still smoking regularly after they were released from the hospital. The smoking rate did decrease following a CVD event, from 28.6 percent before diagnosis to 16.3 percent following diagnosis. In addition, those who continued to smoke were also more likely to cut the number of cigarettes they smoked per day, as well as how long they smoked.

There wasn’t much difference in persistent smoking rates between those who had suffered a stroke—342 subjects—and the 134 patients diagnosed with IHD, Lim and co-authors reported.

A handful of previous smokers, who had quit the habit before experiencing their adverse CVD event, relapsed following their health crisis. Lim and colleagues wrote this was likely due to a feeling of hopelessness or depression following a heart event, which is common in CVD patients.

“The prevalence of depression among patients with cardiac disease is about two to three times higher than that found in the general population,” the authors explained.

Surprisingly, 24 study participants took up smoking after their diagnosis.

Despite the well-established health benefits of ditching cigarettes, especially after a myocardial infarction or stroke, nearly half of all smokers persisted in their routines.

“Considering previous studies which showed intensive smoking cessation interventions during hospitalization increase smoking cessation rates, this finding is indicative of a lost opportunity to promote smoking cessation,” Lin et al. wrote. “In addition, considering that those who remain smokers even after a cardiovascular event have a more negative attitude toward health aspects and are less compliant with their medications, this population should be a target for intensive health education.”