While both run in families, people are more likely to inherit a higher risk for heart attack than for stroke, concluded
researchers whose findings should not only improve our understanding of how genes affect stroke risk, but also suggest we should
probably have separate models for assessing heart attack and stroke risk. You can read their report in the 26 July online first
issue of Circulation: Cardiovascular Genetics.
Senior author Dr Peter M Rothwell, a professor of clinical neurology at UK's Oxford University, and colleagues, examined family history of myocardial infarction (MI, or heart attack), stroke and related risk factors in first degree relatives. He told the media:
"We found that the association between one of your parents having a heart attack and you having a heart attack was a lot stronger than the association between your parent having a stroke and you having a stroke."
He said this implies people's susceptibility to heart attack is more strongly inherited than susceptibility to stroke.
As well as looking at links between patients and their parents, Rothwell and colleagues looked at links between patients and their siblings, and found the same pattern: family history was a stronger predictor of risk for heart attack than it was for stroke.
The researchers, who work in the Stroke Prevention Research Unit at Oxford University, embarked on the study because they wanted to confirm what they had suspected from previous work: that there was a significant difference in genetic predisposition between heart attacks and stroke.
Rothwell said they had already found that much of the heritability of stroke is tied to the genetics of high blood pressure, but that didn't seem to be the case for heart attacks.
For their study, he and his colleagues used data from 906 patients (604 male) with acute heart problems, and 1,015 patients (484 male) who had suffered acute cerebral events, including stroke or transient ischemic attacks (TIAs or "mini-strokes").
The patients were enrolled in the ongoing Oxford Vascular Study (OXVASC), which started in 2002 and is looking at strokes, heart attacks and other vascular events in a part of Oxfordshire where there is one hospital for over 91,000 people.
Lead author Dr Amitava Banerjee has already been analyzing data from OXVASC, and found that genetic predisposition to both heart attack and stroke is important in mother to daughter transmission. He said:
"Family history of heart attacks and family history of strokes have rarely been studied in the same population."
Rothwell and colleagues also found that:
- Of the patients with acute heart problems: 30% had one parent who had suffered a heart attack; 21% had at least one brother or sister who had suffered a heart attack; 7% had two or more brothers and/or sisters who had suffered heart attacks; and 5% had two parents who had suffered heart attacks.
- Of the patients who had suffered strokes or TIAs: 21% had one parent who had suffered a stroke; 2% had two parents who had suffered a stroke; 8% had at least one brother or sister who had suffered a stroke; and 14% had at least two brothers and/or sisters who had suffered a stroke.
- The risk of a patient developing an acute heart problem was 6 times higher if both parents had suffered a heart attack, and 1.5 times higher if only one had suffered a heart attack.
- This compared with the finding that for stroke, parents' history did not make much difference to a patient's stroke risk.
"Heritability of coronary events was greater than that of cerebral events, such that MI was more likely to cluster in families than was stroke."
Rothwell said if others can produce the same results, then the findings imply that the way doctors currently predict a healthy person's risk of heart attack or stroke needs refining, and using the same criteria to predict both could overestimate the risk of stroke.
"Currently, most risk models lump a patient's family history of stroke and heart attack together. We probably should model family history of stroke and heart attack separately in the future," he explained, adding that:
"The knowledge of genetic factors in stroke lags behind that in coronary artery disease. The discovery that genes play a significantly smaller role in stroke could mean that genetic studies of stroke may not be critical to the field."
"Relative Familial Clustering of Cerebral Versus Coronary Ischaemic Events."
Amitava Banerjee, Louise E. Silver, Carl Heneghan, Sarah J.V. Welch, Ziyah Mehta, Adrian P. Banning, and Peter M. Rothwell.
Circ Cardiovasc Genet published online first 26 July 2011 as doi:10.1161/CIRCGENETICS.110.959114
Link to Abstract.
Additional source: AHA.
Written by: Catharine Paddock, PhD