Alcohol Abuse Raises Risk of MI, Heart Failure, AF in Massive Cohort Study

Marlene Busko

January 05, 2017

SAN FRANCISCO, CA — In a large cohort of patients in California, those who abused alcohol had an increased risk of atrial fibrillation (AF), MI, and congestive heart failure (HF), and the added risk was similar to that from traditional risk factors such as type 2 diabetes[1]. Moreover, patients without traditional risk factors who consumed excessive alcohol were disproportionately prone to having these three cardiac outcomes.

These study findings by Dr Isaac R Whitman (University of California, San Francisco) and colleagues were published in the January 3, 2017 issue of the Journal of the American College of Cardiology.

Alcohol abuse "was determined by the treating healthcare provider using ICD9 codes that captured either acute inebriation or evidence of chronic addiction or dependence," senior author Dr Gregory M Marcus (University of California-San Francisco) noted to heartwire from Medscape.

The findings suggest that "alcohol abuse should be considered as a risk factor for cardiovascular disease," and "we should not encourage our patients to drink in the hope that it might reduce their risk for a heart attack," he said.

This study showed that "alcohol abuse is a powerful cardiac risk factor, one of the strongest for AF and at least equivalent to established risk factors for MI and  HF," Drs Michael H Criqui and Isac C Thomas (University of California, San Diego, La Jolla, CA) agree in an accompanying editorial[2].

"The recent infatuation with the potential benefits of light to moderate drinking for CVD protection appears to be based on observational and subtly confounded data, rather than on [clinical-trial] evidence, and perhaps on more than a little wishful thinking," they caution.

"We have to be very careful in interpreting all these data," Marcus agreed. "Taking what evidence is available, it's not unreasonable to drink lightly or in moderation as it might help prevent MI, [but] there is some evidence that even moderate drinking likely increases the risk for AF."

Excess Alcohol, a Modifiable CV Risk Factor

To date, no appropriately powered study has rigorously examined the association between alcohol abuse and MI, HF, and AF, Whitman and colleagues write.

They investigated this in a database of 14,727,591 patients who had ambulatory surgery, emergency visits, or inpatient care visits in California from 2005 through 2009 and who had follow-up data until December 31, 2009. Healthcare practitioners had identified that 268,084 of the patients (1.8%) abused alcohol.

Risk of Cardiac Outcomes With Alcohol Abuse vs No Alcohol Abuse*

Outcome HR (95% CI) P
AF 2.14 (2.08–2.19 <0.0001
MI 1.45 (1.40–1.51) <0.0001
HF 2.34 (2.29–2.39) <0.0001
*Adjusted for age, sex, race, hypertension, diabetes, coronary artery disease (for the AF and HF outcomes), congestive heart failure (for the AF and MI outcomes), chronic kidney disease, valvular heart disease (for the AF and HF outcomes), dyslipidemia, obesity, obstructive sleep apnea, cigarette smoking, and income

Hypertension and HF were by far the most important risks for each outcome, but the risk from alcohol abuse was similar to that from well-established, theoretically modifiable risk factors, Whitman and colleagues write.

They estimate that complete eradication of alcohol abuse would result in more than 73,000 fewer cases of AF, 34,000 fewer MIs, and 91,000 fewer patients with HF in the US.

Study limitations include a lack of information about how much alcohol the patients drank, so they could not determine how much is harmful, the researchers admit.

However, this database "very accurately and specifically" identified patients who had recognized, documented alcohol abuse—who could be targeted for possible intervention, they add.

"Finding that alcohol abuse was associated with a higher risk of MI was somewhat surprising," Marcus said, "given previous data that alcohol seemed to protect against MI. [However,] this likely demonstrates that more is not necessarily better."

Previously, the researchers had showed that people who believe alcohol is healthy tend to drink more, he noted, "so the hope is that this evidence might prohibit such a justification, certainly for drinking alcohol beyond moderation.

"I would tend to favor not more than one alcoholic drink/day for a woman and two alcoholic drinks/day for a man," he said.

It is also important to note that so far, studies about alcohol consumption and CVD have all been observational, so the evidence is not as convincing as from a randomized trial. "We've been fooled before—by estrogen, for example, where it looked like estrogen really protected against heart attack but then randomized trials suggested that it might in fact increase the risk," Marcus cautioned.

"So, where are we now with respect to alcohol consumption and cardiac disease?" Criqui and Thomas ask, rhetorically. "Alcohol is a potentially addictive and dangerous drug, both for the cardiovascular system and multiple other organ systems," they warn.

"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," Whitman and colleagues summarize.

The study was supported by grants from the National Institute on Alcohol Abuse and Alcoholism of the National Institutes of Health. The authors and editorialists have no relevant financial relationships.

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