Harvard researchers who analyzed decades of evidence on links between anger and cardiovascular events, concluded that in the 2 hours following an outburst of anger, there is a higher risk of heart attack, stroke or other cardiovascular event.
The systematic review and meta-analysis - thought to be the first to examine links between anger and cardiovascular outcomes - is published in the European Heart Journal.
First author Dr. Elizabeth Mostofsky and colleagues found that - compared with when they are not angry - a person's risk of heart attack rises nearly five-fold, and the risk of stroke more than three-fold, in the 2 hours following an outburst of anger. Their risk of abnormal heartbeat or ventricular arrhythmia also goes up.
The absolute risk of heart attack, stroke or arrhythmia increased in people who already had a previous history of heart problems, and it also increased the more frequently they were angry.
Heart attack includes myocardial infarction (MI) and acute coronary syndrome (ACS).
Risk of acute cardiovascular event accumulates with frequent episodes of anger
Dr. Mostofsky says:
"Although the risk of experiencing an acute cardiovascular event with any single outburst of anger is relatively low, the risk can accumulate for people with frequent episodes of anger. This is particularly important for people who have higher risk due to other underlying risk factors or those who have already had a heart attack, stroke or diabetes."
Dr. Mostofsky explains that a person with few risk factors who has only one anger outburst per month has a very small additional risk of heart attack or stroke, but someone who has several risk factors already, and is often angry, has a much higher risk that accumulates over time.
The researchers calculated that the annual rate of heart attack per 10,000 people who were angry only once a month would go up by one among those with low cardiovascular risk, and by four in those with high cardiovascular risk.
However, for those who had five outbursts of anger per day, this figure shoots up to 158 extra heart attacks per 10,000 heart attacks each year for those with low cardiovascular risk, and 657 extra heart attacks for those with high cardiovascular risk.
The study was not designed to establish cause and effect, so the researchers cannot be sure that it is being angry that raises the risk for these acute cardiovascular events - they can only say that these things are linked.
For their analysis, the researchers looked for studies carried out between January 1966 and June 2013 and found nine studies linking anger and a range of cardiovascular events that met their criteria for analysis.
From the results of the nine studies they pooled and re-analyzed data on 5,000 heart attacks (mostly MI, some ACS), 800 strokes (three-quarters ischemic, the rest hemorrhagic) and 300 cases of arrhythmia.
Study is the first large, systematic evaluation of links between anger and heart events
The study is important because it is the first to do such a large, systematic evaluation, as Dr. Mostofsky explains:
"Previous studies have shown that outbursts of anger are associated with an immediately higher risk of cardiovascular events, including heart attack and stroke, but since some of these studies were based on small sample sizes with few patients having outbursts of anger, the results were often reported with low precision."
Also, no other systematic reviews had evaluated consistency across studies of the same cardiovascular event, and tested whether the links are similar in size across different types of event, such as between a heart attack and a stroke.
Despite the fact there were several differences in trial features among the studies they included in their analysis - such as the country where the trial took place, the protocols and methods - the evidence they produced pointed consistently toward a definite increase in risk, reasons Dr. Mostofsky:
"Despite the heterogeneity between the studies included in our meta-analysis, all of the studies found that compared to other times, there was a higher rate of cardiovascular events in the 2 hours following outbursts of anger."
Anger may induce heart events via inflammation and changes in blood flow
While they did not examine the underlying cause and effect mechanisms that might link anger and heart events, the authors say it has already been shown that psychological stress can increase heart rate, blood pressure and vascular resistance. These could induce changes in blood flow that lead to blood clots and may trigger inflammatory responses.
In an accompanying editorial, experts not involved with the study say doctors are already convinced of the link between anger and heart conditions, but, they write:
" ... while the long-term link between chronic mental stress, anxiety, depression and hostility with adverse cardiovascular events has been well-established, it has been more difficult to determine the short-term risk of an acute outburst of anger."They say the remaining question is how to prevent these dangerous outbursts, and conclude:
"Given the lessons we have learned from trying to treat depression after MI, treating anger in isolation is unlikely to be impactful. Instead, a broader and more comprehensive approach to treating acute and chronic mental stress, and its associated psychological stressors, is likely to be needed to heal a hostile heart."
In 2012, researchers writing about the science behind mindfulness, said that with continued meditation practice, people can learn to inhibit natural impulses and quell negative emotions and thoughts, such as desire, anger and anxiety, and attain more positive states like compassion, empathy and forgiveness.