After adjusting for multiple variables, adults who abused alcohol had increased risks of atrial fibrillation, MI and congestive heart failure, according to a longitudinal analysis. The relative risk for those outcomes were highest in adults who had no established cardiovascular risk factors.

Lead researcher Isaac R. Whitman, MD, of the University of California-San Francisco, and colleagues published their results online in the Journal of the American College of Cardiology on Jan. 2.

“The risk of [atrial fibrillation], MI and [congestive heart failure] that can be attributed to alcohol abuse is large, suggesting that efforts to mitigate this addictive disease might result in substantial reductions of cardiac disease,” the researchers wrote. “Taken together, these data demonstrate that alcohol in excess should not be considered cardioprotective, but rather cardiotoxic, contributing to heightened risk for all three major, yet distinct, cardiac adverse outcomes.”

The researchers noted that more than 500,000 people in the U.S. had a first-time MI in 2015. Meanwhile, more than six million people have atrial fibrillation, and more than 870,000 people are newly diagnosed with congestive heart failure each year. They added that by 2030, the three conditions would cost the U.S. healthcare system an estimated $400 billion per year.

For this study, the researchers used a database from the Healthcare Cost and Utilization Project. They identified more than 14.7 million adults who were California residents and received care in a California ambulatory surgery unit, emergency department or inpatient hospital unit from 2005 to 2009.

During the study, 1.8 percent of patients were diagnosed with alcohol abuse for an event rate of 6.3 events per 1,000 person-years.

Unadjusted analyses found that adults who abused alcohol had a greater risk of incident atrial fibrillation (hazard ratio [HR], 1.93), MI (HR, 2.03) and congestive heart failure (HR, 2.23).

The risks remained statistically significant after adjusting for variables such as age, sex and race and the presence of coronary disease, current smoking, obesity and other cardiovascular risk factors.

The researchers noted that the increased risk of MI associated with alcohol was of a magnitude similar to that of diabetes and obesity.

“On a population level, the risk of [atrial fibrillation], MI and [congestive heart failure] that could be attributed to alcohol was on a par with multiple other established risk factors,” the researchers wrote. “Extrapolating from our data to the estimated prevalence of each outcome, a theoretical complete eradication of alcohol abuse would result in over 73,000 fewer [atrial fibrillation] cases, 34,000 fewer MIs and 91,000 fewer patients with [congestive heart failure] in the U.S. alone.”

The study had a few limitations, according to the researchers, including that they relied on physician coding, which does not measure potential confounders such as specific diets or levels of activity. They also noted that their endpoints did not capture outpatient encounters.

In addition, this was an observational study, so the researchers could not exclude residual confounding as an explanation for the results. Further, they mentioned that the data could not prove causality.

“More research is needed to understand the mechanisms by which alcohol influences the risk of cardiac disease in specific populations,” the researchers wrote.