In this inception cohort of male health professionals with a first MI, moderate alcohol consumption was inversely associated with total and cardiovascular mortality. This inverse association may be weaker among men with a higher risk of subsequent mortality based on initial MI severity.
Previously, the US Physicians’ Health Study reported that two to six drinks per week at baseline was associated with a 30% lower risk of total and cardiovascular mortality among men with a history of MI.11
Retrospectively recalled moderate alcohol consumption at the time of MI was associated with a reduced risk of total and cardiovascular mortality in the MI Onset Study9
and the Stockholm Heart Epidemiology Program study,10
but the estimates were not statistically significant after adjustment for potential confounders. For post-MI alcohol assessments, habitual moderate wine consumption during follow-up was associated with significantly reduced risk of cardiovascular complications in the Lyon Diet Heart Study;12
however, light-moderate alcohol consumption up to 1 year after MI was not significantly associated with mortality, angina, or hospitalizations in the Prospective Registry Evaluating Myocardial Infarction: Event and Recovery (PREMIER) study.16
This present study differs from the previous studies in several ways. In particular, our study is the first prospective study to evaluate alcohol use before MI occurrence, after incident MI, and long-term risk of mortality. These findings are consistent with results from previous studies that reported moderate alcohol consumption was beneficial among MI survivors, but we further incorporated prospective measures of and changes in alcohol intake, beverage type, detailed adjustment for potential confounders, and additional risk stratification based on MI severity.
The associations of moderate alcohol consumption with lower risk and better prognosis of CVD may work through several biological mechanisms. In a large meta-analysis, moderate alcohol consumption of 30 g/day was associated with a significant 4.0 mg/dL increase in HDL cholesterol.23
In addition to positive HDL effects, moderate alcohol consumption has been associated with improved insulin sensitivity,24
decreased fibrinogen levels,25
and decreased levels of inflammatory markers,26
such as C-reactive protein and interleukin-6. Furthermore, moderate alcohol consumption has been significantly associated with less coronary calcification among asymptomatic subjects27
as well as reduced progression of coronary atherosclerosis among MI survivors with serial angiographic measurements.28
Additionally, some of these effects may have a short latency. In healthy populations29
and in our study, participants who increased their consumption from little or none up to moderate levels had a suggestion of subsequent lower risk of mortality compared with those who stayed abstainers.
We also found that the inverse association of moderate alcohol consumption after MI may depend on initial MI treatment and severity. Anterior wall infarct location is associated with larger infarct size,30
subsequent heart failure,32
and greater risk of mortality,30
compared with non-anterior infarcts. Our results show that moderate alcohol consumption is beneficial among men with non-anterior infarcts. Nevertheless, maybe due to limited sample size, no statistically significant difference was found between non-anterior and anterior group and further research is needed. Additionally, impaired LVEF has been associated with poor prognosis and mortality.33,34
In our study, alcohol consumption was not associated with mortality among men with impaired LVEF. This finding was consistent with the Survival and Ventricular Enlargement (SAVE) trial,15
but not the Optimal Therapy in Myocardial Infarction with the Angiotensin II Antagonist Losartan (OPTIMAAL) trial,13
which only adjusted for age and smoking. Given that anterior MIs have been associated with greater cardiac damage and taken together with our findings based on left ventricular function, moderate alcohol consumption may not be strongly associated with better prognosis among men whose cardiac function after MI is the most severely impaired.
The well-known side effects of excessive alcohol consumption should be considered carefully when providing recommendations to individuals post-MI. For example, heavy alcohol intake decreases LVEF,35
increases blood pressure,36
and acutely inhibits fibrinolysis.37
The MI Onset Study previously reported that the apparent benefit from light drinking after MI was entirely eliminated by episodes of binge drinking.38
Our results also suggest a significant U-shaped association with the greatest benefit observed among moderate drinkers, and a suggestion of excess mortality among men who consumed more than two drinks per day post-MI. Thus, this study emphasizes the importance of alcohol in moderation. Furthermore, this study supports continued moderate alcohol consumption among men previously consuming moderate amounts of alcohol prior to MI, and among men who had better long-term prognosis based on initial MI characteristics and severity. Our findings are consistent with the recent European Society of Cardiology (ESC) recommended guidelines7,8,39
for long-term management of acute coronary syndromes that moderate alcohol consumption of 10–30 g per day in men should not be discouraged and may be beneficial for long-term prognosis after MI.
Several limitations to our study should be addressed. Measurement error often occurs when using self-reported questionnaires. However, the reproducibility and validity of the self-reported questionnaire has been well documented in this population of male health professionals,18,40
and in particular, shown to be highly correlated with the gold standard for measuring alcohol consumption.21
Nonetheless, despite the careful adjustment in multivariable models, alcohol use is associated with other life-style and health-related factors, and residual confounding may exist. Additionally, it should be noted that the treatments reflect the time-period standards at the time of MI occurrence over the last 20 years, and longer follow-up is necessary to study subgroups by more recent treatment regimens such as men with high rates of primary percutaneous coronary intervention. Finally, while we recognize this cohort of male health professionals does not represent a random sample of US men, their relative socioeconomic homogeneity can be considered a strength in reducing residual confounding from unmeasured factors related to socioeconomic status. Additional strengths of this study include the long duration of follow-up, the prospective nature of the data collection which provided unique ability to assess updated alcohol consumption truly before and after MI until the end of follow-up, detailed multivariable adjustment for lifestyle and health factors, subgroup analyses based on characteristics of the initial MI, and also the ability to compare change in alcohol consumption before and after diagnosis of MI.
Our results clearly support the hypothesis that long-term moderate alcohol consumption among individuals with prior MI may be beneficial for all-cause and cardiovascular mortality. This U-shaped association may be stronger among men with better long-term prognosis after MI and further examination is warranted to determine the suitability of moderate alcohol consumption among individuals with other severe cardiovascular conditions.