A systematic review and meta-analysis found that drinking alcohol was associated with higher cardiovascular risk immediately after consumption. After 24 hours, there was a lower risk for moderate drinkers, but the risk increased in heavy drinkers for the following day and week.
Lead researcher Elizabeth Mostofsky, ScD, of the Harvard T.H. Chan School of Public Health in Boston, and colleagues published their results online in Circulation on March 2.
The findings were also presented at the American Heart Association’s Epidemiology/Lifestyle 2016 Scientific meeting in Phoenix.
“There appears to be a transiently higher risk of heart attack and strokes in the hours after drinking an alcoholic beverage but within a day after drinking, only heavy alcohol intake seems to pose a higher cardiovascular risk,” Mostofsky said in a news release.
The researchers searched the CINAHL, Embase PubMed and PsycINFO databases from January 1966 through March 2015. They included cohort, case-control, self-controlled case series or case-crossover studies that reported relative risks and 95 percent confidence intervals for the association between alcohol intake and MI, ischemic stroke or hemorrhagic stroke and retrospectively evaluated alcohol intake from the participant or by proxy for the prior week.
Of the 23 studies that met the inclusion criteria, 16 were case control and seven were case-crossover studies. Three studies assessed alcohol consumption with a questionnaire, while the remaining 20 assessed alcohol consumption with interviews.
The analysis included 29,457 participants: 17,966 had an MI, 2,599 had ischemic stroke and 1,262 had hemorrhagic stroke.
After 24 hours, moderate alcohol consumption (defined as up to six drinks per week) was associated with a 30 percent relative risk reduction for MI and hemorrhagic stroke. Within a week, there was a 19 percent lower relative risk of ischemic stroke. However, six to nine drinks per day nearly doubled the risk of MI and stroke, while 19 to 30 drinks per week increased the risk by up to six times more, according to the researchers.
Within one to three hours of a single dose of alcohol, a person experiences an increase in heart rate, interarterial electromechanical delay and plasminogen activator inhibition levels, according to the researchers. By 12 to 24 hours, they mentioned that a dose equivalent to two alcoholic beverages causes improvements in flow-mediated vasodilatation, endothelial function and fibrinolytic factors.
They added that one to two alcoholic drinks per day was associated with improvements in high-density lipoprotein cholesterol, heart rate variability, endothelial function, insulin sensitivity, coagulation and fibrinolytic cascades as well as a lower risk of cardiovascular disease, ischemic stroke and hemorrhagic stroke.
However, heavy drinking was associated with a higher risk of hypertension, diabetes, cardiovascular disease, ischemic stroke and hemorrhagic stroke as well as mortality after MI.
They noted that heavy drinking is typically defined as 15 or more drinks per week for men and more than eight drinks per week for women, while moderate drinking is up to two drinks per day for men and one drink per day for women.