Quitting Smoking Drastically Improves Survival After Heart Attack

Ron Blankstein, MD

Results of a new analysis are shedding further light on the benefit of quitting smoking in young heart attack survivors.

An analysis of patients with myocardial infarction aged 50 years of age or younger, results indicated quitting smoking was associated with a 70% reduction in all-cause mortality and an 81% reduction in cardiovascular mortality after adjustment for risk factors and propensity score matching.

"These results are definitive: among young people who have had a heart attack, quitting smoking is associated with a substantial benefit," said corresponding author Ron Blankstein, MD, of the Division of Cardiovascular Medicine at Brigham and Women’s Hospital, in a statement. "In cardiology, we are always looking for ways to reduce the risk of cardiovascular events, be it in the form of new medications or other interventions. Our findings show the dramatic magnitude of the effect that quitting smoking can have for young adults.”

Despite being one of the most researched topics in medicine, investigators felt the benefits of smoking cessation in younger patients had often been overlooked by previous studies. To further investigate the potential impact of smoking cessation in this population, investigators designed their study as a retrospective analysis of patients in the Partners YOUNG-MI registry.

Incorporating electronic medical data from Brigham and Women’s Hospital and Massachusetts General Hospital from January 2000-April 2016, a cohort of 2072 patients who experienced a myocardial infarction caused by atherothrombotic coronary artery disease. Investigators pointed out patients who died within 1 year of the index hospitalization and those with known coronary artery disease—defined as prior myocardial infarction or revascularization—were excluded from the analysis.

The median age of this cohort was 45 (Interquartile range [IQR], 42-48) years, 80.6% were women, and 52.5% (n=1088) were smokers at the time of index hospitalization. Of note, the median follow-up period for those with full smoking data was 10.2 (IQR 7.0-13.1) years.

Using data from these patients, investigators hoped to assess associations of smoking and smoking cessation with survival over the follow-up period. Specific outcomes of interest were all-cause and cardiovascular mortality, which were adjudicated independently by a pair of cardiologists. Investigators noted Partners YOUNG-MI registry provided data related to length of index hospital stay, diabetes status, hypertension status, peripheral vascular disease, eGFR, and P2Y12 inhibitor and β-blocker use at discharge for use as covariates in the analysis.

For the purpose of the analysis, smoking cessation was defined as abstinence from inhaled tobacco for at least 3 months immediately before their 1-year follow-up period and without any documented relapse. Of the 1088 current smokers at index hospitalization, 910 had complete follow-up data allowing placement into either group. In total, 343 (37.7%) were classified into the cessation group and 567 (62.3%) were classified into the persistent smoking group.

During the follow-up period, the rate of death among those in the persistent smoking group was more than 3 times greater than those in the cessation group—with rates of 13.2% and 4.1%, respectively (P <.001). In total, 75 of the 567 persistent smokers died compared to 14 of the 343 individuals in the cessation group.

In unadjusted analyses, smoking cessation was associated with a 65% reduction in all-cause mortality (HR, 0.35; 95% CI, 0.19-0.63; P <.001). In the fully-adjusted, propensity score-matched analysis, smoking cessation was associated with a 70% reduction in all-cause mortality (HR, 0.30; 95% CI, 0.16-0.56; P <.001).

When examining cardiovascular mortality, investigators found similar trends. Among patients in the persistent smoking group, 30 of 567 experienced cardiovascular mortality compared to 6 of the 343 patients in the cessation group (P=.008). In unadjusted analyses, smoking cessation was associated with a 71% reduction in cardiovascular mortality (HR, 0.29; 95% CI, 0.11-0.79; P=.02). In the fully-adjusted, propensity score-matched analysis, smoking cessation was associated with an 81% reduction in cardiovascular mortality (HR, 0.19; 95% CI, 0.06-0.56; P=.003).

Investigators pointed out their study has certain limitations. Limitations included the retrospective nature of the analysis, inability to assess smoking status beyond 1 year of follow-up, and the possibility of unmeasured lifestyle factors impacting results.

"These limitations notwithstanding, our findings reinforce the critical importance of smoking cessation, especially among those who experience a heart attack at a young age," added Blankstein, in the aforementioned statement. "Looking at the trajectories of young patients who quit smoking versus those who don't paints a clear picture of the magnitude of risk compared to the benefit of smoking cessation."

This study, “Association of Smoking Cessation and Survival Among Young Adults With Myocardial Infarction in the Partners YOUNG-MI Registry,” was published in JAMA Network Open.